AQA Level 1/Level 2 GCSE (9-1) in Combined Science: Trilogy
Official qualification regulated by Ofqual, awarded by AQA. Classified as a GCSE (9 to 1).
Course Syllabus & Study Modules
Complete breakdown of verified curriculum topics and learning objectives.
Abiotic factors
Abiotic (non-living) factors which can affect a community are:
- Recall and list the main abiotic factors that can affect a community.
- Describe how each named abiotic factor affects organisms through a specific biological process.
- Distinguish abiotic factors from biotic factors when classifying influences on a community.
Abiotic factors
carbon dioxide levels for plants
- State that carbon dioxide is an abiotic factor absorbed by plants through stomata for photosynthesis.
- Explain how changing carbon dioxide concentration affects the rate of photosynthesis and how other factors can become limiting.
- Describe how carbon dioxide concentration can be measured or controlled in an investigation into plant growth.
Abiotic factors
light intensity
- Define light intensity and state a suitable instrument and unit for measuring it.
- Explain how light intensity affects the growth and distribution of plants in a habitat.
- Evaluate how light intensity interacts with other abiotic factors when interpreting ecological data.
Abiotic factors
moisture levels
- Define moisture level as an abiotic factor and state its importance to plants and animals.
- Describe a valid method to measure soil moisture and interpret the result.
- Explain how moisture level affects the distribution or abundance of a named organism.
Abiotic factors
oxygen levels for aquatic animals.
- State that dissolved oxygen is an abiotic factor affecting aquatic animals.
- Explain how temperature, pollution and photosynthesis change dissolved oxygen concentrations in water.
- Interpret data to relate dissolved oxygen levels to the survival or distribution of aquatic organisms.
Abiotic factors
soil pH and mineral content
- State that soil pH and mineral content are abiotic factors and describe their effects on plants.
- Name at least three mineral ions and explain their roles in plant growth.
- Describe how to measure soil pH and interpret how it affects mineral availability and plant distribution.
Abiotic factors
Students should be able to explain how a change in an abiotic factor would affect a given community given appropriate data or context.
- Identify the abiotic factor that has changed and describe the direction of change from the given data or context.
- Construct a logical chain linking the changed factor to the survival, growth or reproduction of named organisms.
- Predict and justify how the change affects the wider community, including possible effects on other species.
Abiotic factors
Students should be able to extract and interpret information from charts, graphs and tables relating to the effect of abiotic factors on organisms within a community.
- Read values and trends accurately from charts, graphs and tables about abiotic factors.
- Explain how a named abiotic factor affects organisms within a community using data as evidence.
- Evaluate the strength of a conclusion drawn from ecological data, recognising correlation and other possible factors.
Abiotic factors
temperature
- State how temperature is measured and describe its effect on enzyme-controlled reactions.
- Explain how temperature influences the distribution and behaviour of ectothermic and endothermic organisms.
- Interpret data to relate temperature to the distribution of organisms while considering other abiotic factors.
Abiotic factors
wind intensity and direction
- State that wind intensity and direction are abiotic factors and name the instruments used to measure them.
- Explain how wind intensity affects transpiration, evaporation, plant damage and seed dispersal.
- Interpret data on species distribution in relation to windward and leeward positions in a habitat.
Acceleration
(HT only) interpret enclosed areas in velocity–time graphs to determine distance travelled (or displacement)
- Identify the enclosed region between a velocity–time line and the time axis.
- Calculate the area of that region by decomposing it into rectangles, triangles or trapezia.
- Distinguish distance from displacement when areas lie below the time axis.
Acceleration
(HT only) measure, when appropriate, the area under a velocity–time graph by counting squares.
- Calculate the physical value represented by one square on a velocity–time grid.
- Count whole and partial squares within the enclosed region to estimate area.
- Convert a square count into a distance in metres and describe the result as an estimate.
Acceleration
(HT only) The distance travelled by an object (or displacement of an object) can be calculated from the area under a velocity–time graph.
- Calculate distance travelled from the area under a velocity–time graph by splitting it into standard shapes (Higher Tier only).
- Distinguish between distance and displacement when areas lie above and below the time axis.
- Estimate the area under a curved velocity–time graph by counting squares or using suitable approximations.
Acceleration
a = Δv / t
- Calculate acceleration using a = Δv ÷ t when the initial velocity, final velocity and time are given.
- Calculate the change in velocity or the time taken by rearranging a = Δv ÷ t.
- Interpret the sign of a calculated acceleration as speeding up or slowing down.
Acceleration
acceleration = change in velocitʸ
- Use acceleration = change in velocity ÷ time to calculate average acceleration.
- Rearrange the equation to find change in velocity or time.
- Explain the meaning of a negative acceleration in terms of direction and deceleration.
Acceleration
acceleration, a, in metres per second squared, m/s²
- State the unit of acceleration as metres per second squared, m/s².
- Explain how the unit m/s² arises from velocity change divided by time.
- Interpret the meaning of a given acceleration value, including its sign, in terms of velocity change per second.
Acceleration
An object falling through a fluid initially accelerates due to the force of gravity. Eventually the resultant force will be zero and the object will move at its terminal velocity.
- Describe how the forces on an object falling through a fluid change as its speed increases.
- Explain why terminal velocity is reached when the resultant force is zero.
- Apply the concept of terminal velocity to explain the motion of objects such as skydivers or objects falling in liquids.
Acceleration
An object that slows down is decelerating.
- Define deceleration as acceleration in the direction opposite to motion.
- Calculate acceleration and interpret the sign to identify deceleration.
- Identify deceleration from velocity–time and distance–time graphs.
Acceleration
change in velocity, ∆v, in metres per second, m/s
- Calculate the change in velocity using final velocity minus initial velocity.
- Interpret the sign of ∆v as speeding up or slowing down.
- State the unit of change in velocity as metres per second, m/s.
Acceleration
distance, s, in metres, m
- State that distance s is measured in metres and is a scalar quantity.
- Calculate distance travelled during uniform acceleration using v² − u² = 2 × a × s.
- Convert a distance given in cm or km into metres before using it in an equation.
Acceleration
draw velocity–time graphs from measurements and interpret lines and slopes to determine acceleration
- Construct an accurate velocity–time graph from a table of measurements.
- Calculate acceleration from the slope of a velocity–time graph.
- Interpret changes in slope to identify acceleration, constant velocity and deceleration.
Acceleration
final velocity ² −initial velocity ² = 2 × acceleration × distance
- Select and apply v² − u² = 2 × a × s to solve problems involving uniform acceleration.
- Rearrange the equation correctly to find acceleration, final velocity, initial velocity or distance.
- Interpret the sign and magnitude of calculated values in the context of motion.
Acceleration
final velocity, v, in metres per second, m/s
- Define final velocity and state its unit as m/s.
- Identify the final velocity value from a description or graph of motion.
- Use final velocity correctly in kinematic equations and interpret its sign.
Acceleration
initial velocity, u, in metres per second, m/s
- Define initial velocity u and give its SI unit as m/s.
- Substitute a correct value of u, including zero or a negative value, into a = (v − u) ÷ t.
- Convert a speed from km/h to m/s before using it as u in a calculation.
Acceleration
Near the Earth’s surface any object falling freely under gravity has an acceleration of about 9.8 m/s².
- State the approximate acceleration of free fall near the Earth’s surface and its direction.
- Explain why all objects in free fall have the same acceleration regardless of mass.
- Apply a = Δv / Δt or v = u + at to solve problems involving objects falling freely under gravity.
Acceleration
Students should be able to estimate the magnitude of everyday accelerations.
- Estimate the magnitude of acceleration in everyday situations using typical values.
- Use the equation a = Δv ÷ t with approximate data to calculate acceleration.
- Evaluate the reasonableness of an estimated acceleration by comparison with known benchmarks.
Acceleration
The acceleration of an object can be calculated from the gradient of a velocity–time graph.
- Calculate acceleration from the gradient of a straight-line section of a velocity–time graph, including correct units.
- Interpret positive, negative, zero and changing gradients in terms of an object's motion.
- Determine acceleration at a point on a curved velocity–time graph by drawing and using a tangent.
Acceleration
The average acceleration of an object can be calculated using the equation:
- Calculate average acceleration from a stated change in velocity and time interval.
- Apply the equation acceleration = change in velocity ÷ time to numerical data.
- Interpret the sign and unit of an acceleration value in context.
Acceleration
The following equation applies to uniform acceleration:
- State the condition under which the equation v² − u² = 2 × a × s applies.
- Identify from a description or graph whether acceleration is uniform.
- Apply the equation correctly to a single uniform-acceleration stage of motion.
Acceleration
time, t, in seconds, s
- Identify the correct time interval for a velocity change.
- Convert times given in minutes to seconds.
- Substitute time in seconds into the acceleration equation.
Acceleration
v² − u² = 2as
- Select and apply v² − u² = 2as to solve for an unknown velocity, acceleration or displacement.
- Substitute values with correct units and signs into the equation.
- Rearrange the equation to isolate a squared term and evaluate the final answer with its unit.
Active transport
Active transport allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil. Plants require ions for healthy growth.
- Describe how root hair cells absorb mineral ions from dilute soil solution by active transport.
- Explain why active transport is needed for mineral ion uptake and how the structure of a root hair cell supports this process.
- State why plants require mineral ions for healthy growth and give examples of substances made using them.
Active transport
Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). This requires energy from respiration.
- State the direction of movement in active transport and identify it as movement against a concentration gradient.
- Explain why active transport requires energy and identify respiration as the source of that energy.
- Apply the concept of active transport to a named example, such as absorption of mineral ions by a root hair cell.
Active transport
describe how substances are transported into and out of cells by diffusion, osmosis and active transport
- Describe diffusion as the net movement of particles from higher to lower concentration, down a concentration gradient, without requiring energy.
- Describe osmosis as the net movement of water molecules across a partially permeable membrane from a dilute solution to a concentrated solution.
- Describe active transport as the movement of substances against a concentration gradient, requiring energy from respiration.
Active transport
explain the differences between the three processes.
- Explain that diffusion and osmosis are passive, whereas active transport requires energy from respiration.
- Explain that diffusion moves any particles down a concentration gradient, osmosis moves water across a partially permeable membrane, and active transport moves substances against a concentration gradient.
- Compare the three processes using correct terminology, including concentration gradients, partially permeable membranes and carrier proteins.
Active transport
It also allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration. Sugar molecules are used for cell respiration.
- Describe how sugar molecules are absorbed from the gut into the blood when the gut concentration is lower than the blood concentration.
- Explain why active transport, rather than diffusion, is required for this absorption.
- Relate the absorbed sugar molecules to their use in cell respiration.
Adaptations
Organisms have features (adaptations) that enable them to survive in the conditions in which they normally live. These adaptations may be structural, behavioural or functional.
- State that adaptations are features enabling organisms to survive in the conditions where they normally live.
- Classify given adaptations as structural, behavioural or functional with a correct reason.
- Explain how a named adaptation improves survival or reproduction in a stated habitat.
Adaptations
Some organisms live in environments that are very extreme, such as at high temperature, pressure, or salt concentration. These organisms are called extremophiles. Bacteria living in deep sea vents are extremophiles.
- Define extremophile and give examples of extreme environments.
- Describe how deep sea vent bacteria survive high temperature and high pressure.
- Explain why extremophile enzymes and cell structures must remain functional in extreme conditions.
Adaptations
Students should be able to explain how organisms are adapted to live in their natural environment, given appropriate information.
- Identify structural, behavioural and functional adaptations from given information.
- Explain how a named adaptation increases an organism's chance of survival or reproduction.
- Apply adaptation ideas to organisms in different natural environments.
Aerobic and anaerobic respiration
Aerobic respiration is represented by the equation:
- Recall and write the word equation for aerobic respiration.
- Write and balance the symbol equation for aerobic respiration.
- Use the equation to explain the need for increased oxygen supply and carbon dioxide removal during exercise.
Aerobic and anaerobic respiration
Anaerobic respiration in muscles is represented by the equation:
- Recall and write the word equation for anaerobic respiration in muscles.
- Describe when anaerobic respiration occurs in muscle cells during exercise.
- Explain how lactic acid production leads to fatigue and the oxygen debt.
Aerobic and anaerobic respiration
Anaerobic respiration in plant and yeast cells is represented by the equation:
- Write the word and balanced symbol equation for anaerobic respiration in plant and yeast cells.
- Identify ethanol and carbon dioxide as the products of this process.
- Describe a commercial or environmental context in which this process occurs.
Aerobic and anaerobic respiration
Anaerobic respiration in yeast cells is called fermentation and has economic importance in the manufacture of bread and alcoholic drinks.
- Define fermentation as anaerobic respiration in yeast cells.
- Describe the products of fermentation and their roles in bread-making and alcoholic drinks.
- Explain the economic importance of fermentation in food and drink manufacture.
Aerobic and anaerobic respiration
As the oxidation of glucose is incomplete in anaerobic respiration much less energy is transferred than in aerobic respiration.
- State that anaerobic respiration transfers much less energy than aerobic respiration.
- Explain that anaerobic respiration involves incomplete oxidation of glucose.
- Compare the energy transferred in aerobic and anaerobic respiration using the idea of complete versus incomplete oxidation.
Aerobic and anaerobic respiration
chemical reactions to build larger molecules
- State that respiration provides energy for reactions that build larger molecules from smaller ones.
- Give examples of larger molecules built in cells, including glycogen, proteins, lipids, starch, and cellulose.
- Explain how small molecules are joined together and why these reactions are important for growth and storage.
Aerobic and anaerobic respiration
glucose + oxygen carbon dioxide + water
- Write the word equation for aerobic respiration with the correct reactants and products.
- Describe how aerobic respiration transfers energy for cell processes.
- Apply the equation to explain changes during exercise, such as increased breathing and heart rate.
Aerobic and anaerobic respiration
glucose ethanol + carbon dioxide
- Write the word equation for fermentation in yeast.
- Identify glucose as the reactant and ethanol and carbon dioxide as the products.
- Describe how fermentation is used in bread-making and in the manufacture of alcoholic drinks.
Aerobic and anaerobic respiration
glucose lactic acid
- Name glucose and lactic acid as the substances in the muscle anaerobic respiration equation.
- Construct the word equation glucose → lactic acid.
- Describe the conditions and consequences of this reaction in muscle cells.
Aerobic and anaerobic respiration
keeping warm.
- Describe how aerobic respiration transfers energy, some of which keeps the body warm.
- Explain how shivering increases the rate of respiration to help maintain a constant core temperature.
- Apply the concept of energy transfer in respiration to a familiar example such as keeping warm in a cold environment.
Aerobic and anaerobic respiration
movement
- Describe how respiration supplies the energy needed for muscle contraction and movement.
- Compare aerobic and anaerobic respiration in muscles during rest and vigorous exercise.
- Explain the cause and repayment of oxygen debt after exercise.
Aerobic and anaerobic respiration
Organisms need energy for:
- List the life processes that require energy transferred by respiration.
- Give named examples of building reactions, movement, temperature regulation and active transport that use this energy.
- Explain that respiration transfers energy rather than making it.
Aerobic and anaerobic respiration
Respiration in cells can take place aerobically (using oxygen) or anaerobically (without oxygen), to transfer energy.
- State the word equations for aerobic respiration and for anaerobic respiration in animals, plants and yeast.
- Compare aerobic and anaerobic respiration in terms of oxygen use, products and energy transferred.
- Explain why muscle cells respire anaerobically during vigorous exercise.
Aerobic and anaerobic respiration
Students should be able to compare the processes of aerobic and anaerobic respiration with regard to the need for oxygen, the differing products and the relative amounts of energy transferred.
- State the oxygen requirement for aerobic and anaerobic respiration.
- Identify the products of aerobic respiration and of anaerobic respiration in animals, plants and yeast.
- Compare the relative amounts of energy transferred by aerobic and anaerobic respiration per glucose molecule.
Aerobic and anaerobic respiration
Students should be able to describe cellular respiration as an exothermic reaction which is continuously occurring in living cells.
- Describe cellular respiration as an exothermic reaction that transfers energy.
- Explain that respiration occurs continuously in all living cells.
- Compare aerobic and anaerobic respiration in terms of oxygen use and energy transferred.
Aerobic and anaerobic respiration
Students should recognise the chemical symbols: C₆H₁₂O₆, O₂, CO₂ and H₂O.
- Name the substance represented by each of the symbols C₆H₁₂O₆, O₂, CO₂ and H₂O.
- Interpret subscripts to state the number of atoms of each element in a formula.
- Use the symbols to write the balanced symbol equation for aerobic respiration.
Aerobic and anaerobic respiration
The energy transferred supplies all the energy needed for living processes.
- State that respiration transfers energy from glucose for all living processes.
- Give at least three examples of living processes that use this transferred energy.
- Explain why a continuous energy supply is essential for cell function and survival.
Alternative methods of extracting metals (HT only)
Bioleaching uses bacteria to produce leachate solutions that contain metal compounds.
- Describe how bacteria produce leachate from metal ores.
- Identify leachate as a solution containing metal compounds.
- Explain why bioleaching is useful for low-grade ores.
Alternative methods of extracting metals (HT only)
Copper ores are becoming scarce and new ways of extracting copper from low-grade ores include phytomining, and bioleaching. These methods avoid traditional mining methods of digging, moving and disposing of large amounts of rock.
- Explain why copper ores are becoming scarce and why low-grade ores are increasingly used.
- Describe how phytomining and bioleaching extract copper from low-grade ores.
- Compare these alternative methods with traditional mining in terms of digging, moving and disposing of rock.
Alternative methods of extracting metals (HT only)
Phytomining uses plants to absorb metal compounds. The plants are harvested and then burned to produce ash that contains metal compounds.
- Describe how plants absorb metal compounds in phytomining.
- Explain why harvested plants are burned and how ash contains metal compounds.
- Outline how copper is obtained from the ash produced by phytomining.
Alternative methods of extracting metals (HT only)
Students should be able to evaluate alternative biological methods of metal extraction, given appropriate information.
- Describe how bioleaching and phytomining extract metals from low-grade sources.
- Compare biological and traditional extraction methods using supplied information.
- Reach and justify a conclusion about the suitability of a biological method in a given context.
Alternative methods of extracting metals (HT only)
The Earth’s resources of metal ores are limited.
- Explain why metal ores are described as limited or finite resources.
- Describe how recycling and alternative extraction methods help conserve metal ores.
- Assess the benefits and limitations of using low-grade ores and recycled metals.
Alternative methods of extracting metals (HT only)
The metal compounds can be processed to obtain the metal. For example, copper can be obtained from solutions of copper compounds by displacement using scrap iron or by electrolysis.
- Describe the displacement of copper using scrap iron.
- Describe the electrolysis of copper solutions to obtain pure copper.
- Compare displacement and electrolysis for obtaining copper from leachate.
Amounts of substances in equations (HT only)
calculate the masses of reactants and products from the balanced symbol equation and the mass of a given reactant or product.
- Convert a given mass of a reactant or product into moles using its relative formula mass.
- Apply the mole ratio from a balanced symbol equation to find the moles of another substance.
- Convert the moles of the required substance into its mass in grams.
Amounts of substances in equations (HT only)
calculate the masses of substances shown in a balanced symbol equation
- Calculate relative formula masses from a given chemical formula.
- Use a balanced symbol equation to convert between masses of different substances.
- Verify a mass calculation by checking the conservation of mass.
Amounts of substances in equations (HT only)
Chemical equations can be interpreted in terms of moles. For example:
- State the mole ratio from a balanced symbol equation.
- Explain what the coefficients in an equation represent in terms of moles.
- Use a mole ratio to calculate the amount of a reactant or product from a given amount in moles.
Amounts of substances in equations (HT only)
Mg + 2HCl → MgCl₂ + H₂
- Interpret the coefficients in Mg + 2HCl → MgCl₂ + H₂ as a mole ratio.
- Convert between mass and moles using the equation.
- Distinguish coefficients from subscripts when balancing and using equations.
Amounts of substances in equations (HT only)
shows that one mole of magnesium reacts with two moles of hydrochloric acid to produce one mole of magnesium chloride and one mole of hydrogen gas.
- Use the coefficients in a balanced equation to state mole ratios.
- Perform a multi-step calculation from a given mass to moles of another reactant or product.
- Explain why mole ratios, not mass ratios, are taken directly from an equation.
Amounts of substances in equations (HT only)
The masses of reactants and products can be calculated from balanced symbol equations.
- Balance a symbol equation and state the mole ratio of reactants and products.
- Convert between mass and moles using n = m ÷ Mᵣ and m = n × Mᵣ.
- Use a balanced equation to calculate the mass of a reactant or product from a given mass.
Animal and plant cells
a cell membrane
- Label the cell membrane on a diagram of an animal or plant cell.
- Describe the function of the cell membrane in controlling substance movement.
- Explain how the membrane's partially permeable nature relates to diffusion, osmosis and active transport.
Animal and plant cells
a nucleus
- Identify the nucleus on diagrams and microscope images of animal and plant cells.
- Describe the function of the nucleus in controlling cell activities and holding genetic material.
- Compare the presence of a nucleus in eukaryotic and prokaryotic cells.
Animal and plant cells
a permanent vacuole filled with cell sap.
- Identify the permanent vacuole in diagrams of plant cells.
- State the function of the permanent vacuole and cell sap.
- Explain how the vacuole contributes to turgor pressure and cell support.
Animal and plant cells
chloroplasts
- Identify chloroplasts in diagrams of plant cells.
- State the function of chloroplasts in photosynthesis.
- Explain how the structure of chloroplasts relates to their function.
Animal and plant cells
cytoplasm
- Identify the cytoplasm on diagrams and microscope images of animal and plant cells.
- Describe the role of the cytoplasm as the site of many chemical reactions.
- Explain how the cytoplasm supports and positions organelles within the cell.
Animal and plant cells
In addition to the parts found in animal cells, plant cells often have:
- List the additional structures found in plant cells compared with animal cells.
- Describe the function of the cell wall, chloroplasts and permanent vacuole.
- Compare plant and animal cells, including the parts they share.
Animal and plant cells
mitochondria
- Identify mitochondria on a diagram or micrograph of a cell.
- Describe the role of mitochondria in aerobic respiration and energy release.
- Relate the number of mitochondria in a cell to its energy requirements.
Animal and plant cells
Most animal cells have the following parts:
- List the main parts of a typical animal cell.
- State the function of each main part of an animal cell.
- Compare animal cells with plant cells in terms of their structures.
Animal and plant cells
Plant and algal cells also have a cell wall made of cellulose, which strengthens the cell.
- Identify the cell wall as a structure present in plant and algal cells but absent in animal cells.
- Describe the cell wall as being made of cellulose and located outside the cell-surface membrane.
- Explain how the cellulose cell wall strengthens the cell and helps prevent osmotic bursting.
Animal and plant cells
Required practical activity 1: use a light microscope to observe, draw and label a selection of plant and animal cells. A magnification scale must be included.
- Prepare and focus a slide of plant and animal cells using a light microscope correctly.
- Produce clear, labelled biological drawings that show observed cell structures accurately.
- Calculate and include a magnification scale on a drawing using image size and actual size.
Animal and plant cells
ribosomes.
- Identify ribosomes as small structures in the cytoplasm of cells.
- Describe the function of ribosomes in protein synthesis.
- Relate the number of ribosomes to the protein-secreting activity of a cell.
Animal and plant cells
Students should be able to explain how the main sub-cellular structures, including the nucleus, cell membranes, mitochondria, chloroplasts in plant cells and plasmids in bacterial cells are related to their functions.
- State the function of the nucleus, cell membrane, mitochondria, chloroplasts and plasmids.
- Explain how each named sub-cellular structure is adapted to its function.
- Compare the sub-cellular structures of animal, plant and bacterial cells.
Animal and plant cells
Students should be able to use estimations and explain when they should be used to judge the relative size or area of sub-cellular structures.
- Use estimation to judge the relative size or area of sub-cellular structures from images or data.
- Explain when estimation is appropriate, such as when structures are too small or irregular to measure directly.
- Calculate an approximate actual size using image size and magnification or a scale bar, giving the answer with a suitable unit.
Antibiotics and painkillers
Antibiotics cannot kill viral pathogens.
- State that antibiotics cannot kill viral pathogens.
- Explain why antibiotics are ineffective against viruses by comparing bacterial and viral structure.
- Identify viral infections that are not treated with antibiotics.
Antibiotics and painkillers
Antibiotics, such as penicillin, are medicines that help to cure bacterial disease by killing infective bacteria inside the body. It is important that specific bacteria should be treated by specific antibiotics.
- Describe how antibiotics such as penicillin kill infective bacteria inside the body.
- Explain why a specific antibiotic is needed for a specific bacterium.
- Apply knowledge of antibiotic specificity to a named infection scenario.
Antibiotics and painkillers
It is difficult to develop drugs that kill viruses without also damaging the body’s tissues.
- Explain why it is difficult to develop drugs that kill viruses without damaging body tissues.
- State that antibiotics do not work on viruses.
- Describe how viruses reproduce inside host cells and why this complicates drug development.
Antibiotics and painkillers
Painkillers and other medicines are used to treat the symptoms of disease but do not kill pathogens.
- State that painkillers treat symptoms of disease but do not kill pathogens.
- Distinguish between medicines that relieve symptoms and antibiotics that kill bacteria.
- Explain why a patient may still need their immune system to clear an infection when taking a painkiller.
Antibiotics and painkillers
Students should be able to explain the use of antibiotics and other medicines in treating disease.
- State that antibiotics kill infective bacteria and are ineffective against viruses.
- Distinguish between medicines that cure infection and medicines that only relieve symptoms.
- Justify a treatment choice by linking the type of pathogen to the action of the medicine.
Antibiotics and painkillers
The use of antibiotics has greatly reduced deaths from infectious bacterial diseases. However, the emergence of strains resistant to antibiotics is of great concern.
- State that antibiotics kill bacteria and have greatly reduced deaths from bacterial diseases.
- Explain how mutation and selection lead to antibiotic-resistant strains.
- Describe why resistant strains are of great concern and how overuse contributes.
Atmospheric pollutants from fuels
describe how carbon monoxide, soot (carbon particles), sulfur dioxide and oxides of nitrogen are produced by burning fuels
- Describe how carbon monoxide and soot are produced by the incomplete combustion of fuels in a limited supply of oxygen.
- Describe how sulfur dioxide is produced from sulfur impurities in fuels during burning.
- Describe how oxides of nitrogen are produced when nitrogen and oxygen from the air react at high temperatures in engines or furnaces.
Atmospheric pollutants from fuels
Most fuels, including coal, contain carbon and/or hydrogen and may also contain some sulfur.
- State that most fuels contain carbon and/or hydrogen.
- Identify that some fuels, including coal, may also contain sulfur.
- Use the composition of a fuel to predict possible combustion products.
Atmospheric pollutants from fuels
predict the products of combustion of a fuel given appropriate information about the composition of the fuel and the conditions in which it is used.
- Predict the products formed when a named fuel burns in a plentiful or a limited supply of oxygen.
- Deduce the products of combustion from information about a fuel's composition, including carbon, hydrogen and sulfur content.
- Write word and balanced symbol equations for the complete and incomplete combustion of simple fuels.
Atmospheric pollutants from fuels
The combustion of fuels is a major source of atmospheric pollutants.
- Name the main products of complete and incomplete combustion of fuels.
- Describe the environmental or health effect of carbon dioxide, sulfur dioxide, nitrogen oxides, carbon monoxide and particulates.
- Write a balanced equation for the complete combustion of a simple fuel such as methane.
Atmospheric pollutants from fuels
The gases released into the atmosphere when a fuel is burned may include carbon dioxide, water vapour, carbon monoxide, sulfur dioxide and oxides of nitrogen. Solid particles and unburned hydrocarbons may also be released that form particulates in the atmosphere.
- List the gases that may be released into the atmosphere when a fuel is burned.
- Explain how carbon monoxide, sulfur dioxide and oxides of nitrogen are formed during combustion.
- Describe how solid particles and unburned hydrocarbons form particulates in the atmosphere.
Atoms, elements and compounds
(HT only) write balanced half equations and ionic equations where appropriate.
- Construct balanced half equations for oxidation and reduction processes, including the correct number of electrons.
- Derive ionic equations from full equations by removing spectator ions.
- Apply state symbols correctly to species in half equations and ionic equations.
Atoms, elements and compounds
All substances are made of atoms. An atom is the smallest part of an element that can exist.
- Describe that all substances are made of atoms.
- Define an atom as the smallest part of an element that can exist.
- Give examples showing that different elements are made of different atoms.
Atoms, elements and compounds
Atoms of each element are represented by a chemical symbol, eg O represents an atom of oxygen, Na represents an atom of sodium.
- Recall that each element is represented by its own chemical symbol.
- Write and interpret symbols such as O, Na, Mg and Cl correctly.
- Use a formula to state the number of atoms of each element present.
Atoms, elements and compounds
Chemical reactions can be represented by word equations or equations using symbols and formulae.
- Convert a named reaction into a correct word equation.
- Construct a balanced symbol equation from given formulae.
- Check an equation by counting atoms of each element on both sides.
Atoms, elements and compounds
Compounds are formed from elements by chemical reactions. Chemical reactions always involve the formation of one or more new substances, and often involve a detectable energy change. Compounds contain two or more elements chemically combined in fixed proportions and can be represented by formulae using the symbols of the atoms from which they were formed. Compounds can only be separated into elements by chemical reactions.
- Describe how compounds are formed from elements by chemical reactions.
- Interpret chemical formulae to identify the elements and their fixed proportions in a compound.
- Explain why compounds can only be separated into elements by chemical reactions.
Atoms, elements and compounds
name compounds of these elements from given formulae or symbol equations
- Construct the correct name of a compound from its formula, applying prefixes for covalent compounds and Roman numerals for transition metals.
- Identify the elements present in a given chemical formula or symbol equation.
- Name compounds formed in symbol equations, distinguishing compounds from elements.
Atoms, elements and compounds
Students will be supplied with a periodic table for the exam and should be able to:
- Use the periodic table to find names and symbols of key elements.
- Name compounds from given formulae and write word equations for reactions.
- Write formulae and balanced chemical equations for reactions in the specification.
Atoms, elements and compounds
There are about 100 different elements. Elements are shown in the periodic table.
- Define an element as a substance made of only one type of atom.
- Locate elements in the periodic table using their symbols and atomic numbers.
- Explain how the position of an element in the periodic table relates to its properties.
Atoms, elements and compounds
use the names and symbols of the first 20 elements in the periodic table, the elements in Groups 1 and 7, and other elements in this specification
- Recall the names and symbols of the first 20 elements in the periodic table.
- Recall the names and symbols of the elements in Groups 1 and 7.
- Recall the names and symbols of other elements named in the specification, such as iron, copper and zinc.
Atoms, elements and compounds
write formulae and balanced chemical equations for the reactions in this specification.
- Write correct chemical formulae from names or ions, including formulae with brackets.
- Balance chemical equations by adjusting coefficients so that each element is conserved.
- Apply formulae and balanced equations to the reactions named in the specification, including acid and combustion reactions.
Atoms, elements and compounds
write word equations for the reactions in this specification
- Write a word equation with reactants on the left and products on the right for a named reaction.
- Use correct chemical names for all reactants and products in a word equation.
- Apply word equations to the reactions listed in the specification, including acid reactions and combustion.
Bacterial diseases
Gonorrhoea is a sexually transmitted disease (STD) with symptoms of a thick yellow or green discharge from the vagina or penis and pain on urinating. It is caused by a bacterium and was easily treated with the antibiotic penicillin until many resistant strains appeared. Gonorrhoea is spread by sexual contact. The spread can be controlled by treatment with antibiotics or the use of a barrier method of contraception such as a condom.
- Describe the symptoms of gonorrhoea as a thick yellow or green discharge from the vagina or penis and pain on urinating.
- Explain that gonorrhoea is caused by a bacterium, spread by sexual contact, and was easily treated with penicillin until resistant strains appeared.
- Describe how the spread of gonorrhoea can be controlled by antibiotics or by using a barrier method of contraception such as a condom.
Bacterial diseases
Salmonella food poisoning is spread by bacteria ingested in food, or on food prepared in unhygienic conditions. In the UK, poultry are vaccinated against salmonella to control the spread. Fever, abdominal cramps, vomiting and diarrhoea are caused by the bacteria and the toxins they secrete.
- Describe how salmonella food poisoning is spread by bacteria ingested in food or on food prepared in unhygienic conditions.
- Explain how vaccination of poultry in the UK helps control the spread of salmonella.
- Identify fever, abdominal cramps, vomiting and diarrhoea as symptoms caused by salmonella bacteria and the toxins they secrete.
Biodiversity
A great biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment.
- Describe what biodiversity is and give examples of species variety in an ecosystem.
- Explain how greater biodiversity reduces the dependence of one species on another for food and shelter.
- Apply the idea of stability to predict the effect of losing a species from a species-rich and a species-poor ecosystem.
Biodiversity
Biodiversity is the variety of all the different species of organisms on earth, or within an ecosystem.
- State that biodiversity is the variety of all the different species of organisms.
- Apply the concept of biodiversity to the whole earth or to a named ecosystem.
- Explain how high biodiversity contributes to ecosystem stability by reducing species dependence.
Biodiversity
The future of the human species on Earth relies on us maintaining a good level of biodiversity. Many human activities are reducing biodiversity and only recently have measures been taken to try to stop this reduction.
- Describe how human activities such as deforestation and pollution reduce biodiversity.
- Explain why maintaining biodiversity is important for the future of the human species.
- Evaluate the effectiveness of recent measures taken to stop the reduction in biodiversity.
Biotic factors
availability of food
- Define food availability as a biotic factor and explain why it is biotic.
- Explain how changes in food availability affect survival, reproduction and population size.
- Apply the concept to a named habitat and organism, using competition and energy transfer ideas.
Biotic factors
Biotic (living) factors which can affect a community are:
- Recall the main biotic factors that affect a community.
- Distinguish biotic factors from abiotic factors.
- Describe how each named biotic factor can change a population.
Biotic factors
new pathogens
- Define a pathogen and classify it as a biotic factor.
- Explain how a new pathogen can reduce population size when immunity is low.
- Apply the concept of a new pathogen to a named population and predict the effect on numbers.
Biotic factors
new predators arriving
- Identify a new predator as a biotic factor and explain why it is biotic.
- Explain how a new predator can change prey numbers and then its own numbers.
- Apply predator–prey reasoning to a named example and describe an indirect effect on another species.
Biotic factors
one species outcompeting another so the numbers are no longer sufficient to breed.
- Describe how one species can outcompete another for limited resources.
- Explain why a very small population may no longer be sufficient to breed.
- Predict the effect of competitive exclusion on population numbers and community structure.
Biotic factors
Students should be able to explain how a change in a biotic factor might affect a given community given appropriate data or context.
- Identify the biotic factor that has changed in a given context or data set.
- Describe the effect of that change on a named population.
- Explain how the effect transfers to other populations and changes the community.
Biotic factors
Students should be able to extract and interpret information from charts, graphs and tables relating to the effect of biotic factors on organisms within a community.
- Read values accurately from charts, graphs and tables about biotic factors.
- Describe trends in data and link them to named biotic factors.
- Explain how a biotic factor affects organisms in a community using data as evidence.
Blood
Blood is a tissue consisting of plasma, in which the red blood cells, white blood cells and platelets are suspended.
- Identify plasma, red blood cells, white blood cells and platelets as the components of blood.
- Describe the function of each blood component and link at least one structural feature to its function.
- Explain why blood is classified as a tissue rather than a single liquid.
Blood
Students should be able to recognise different types of blood cells in a photograph or diagram, and explain how they are adapted to their functions.
- Identify red blood cells, white blood cells and platelets from a photograph or diagram using visible features.
- Describe how the structure of each blood cell type is adapted to its function.
- Explain the link between cell adaptations and their roles in transport, defence and clotting.
Blood
Students should know the functions of each of these blood components.
- State the function of plasma, red blood cells, white blood cells and platelets.
- Explain how the structure of red blood cells and white blood cells relates to their functions.
- Apply knowledge of blood component functions to explain simple clinical effects such as anaemia or poor clotting.
Calculating rates of reactions
(HT only) calculate the gradient of a tangent to the curve on these graphs as a measure of rate of reaction at a specific time.
- Draw a tangent to a rate curve at a specified time, including at t=0.
- Calculate the gradient of that tangent using two points on the line.
- Interpret the gradient as the rate of reaction at that specific time, including its units.
Calculating rates of reactions
calculate the mean rate of a reaction from given information about the quantity of a reactant used or the quantity of a product formed and the time taken
- Apply the equation mean rate = change in quantity ÷ time taken to data about a reactant used or a product formed.
- Calculate the change in quantity correctly when initial and final readings are both given.
- Express a calculated mean rate with the correct compound unit and an appropriate number of significant figures.
Calculating rates of reactions
draw tangents to the curves on these graphs and use the slope of the tangent as a measure of the rate of reaction
- Draw an accurate tangent to a curve at a specified time.
- Use the slope of a tangent as a measure of the rate of reaction.
- Compare rates of reaction at different times by comparing the steepness of tangents.
Calculating rates of reactions
draw, and interpret, graphs showing the quantity of product formed or quantity of reactant used up against time
- Plot quantity against time accurately with labelled axes and suitable scales.
- Describe how the gradient of the curve relates to the rate of reaction.
- Explain what a plateau on the curve shows about the reaction.
Calculating rates of reactions
For the Higher Tier, students are also required to use quantity of reactants in terms of moles and units for rate of reaction in mol/s.
- Calculate the amount of reactant in moles and use it to determine a rate of reaction in mol/s.
- Convert mass data into moles using molar mass before calculating a rate.
- Apply the unit mol/s correctly when expressing a rate of reaction from mole data.
Calculating rates of reactions
mean rate of reaction = quantity of product formed / time taken
- Calculate the mean rate of reaction from a measured quantity of product and a measured time.
- Select the correct change in quantity and time interval from tabulated or graphical data.
- Express the mean rate with the correct compound unit.
Calculating rates of reactions
mean rate of reaction = quantity of reactant used / time taken
- Calculate the mean rate of a reaction using the quantity of reactant used or product formed and the time taken.
- Use correct units for mean rate when the quantity is measured as volume, mass or amount in moles (Higher Tier only).
- Compare mean rates of different reactions or conditions using calculated values.
Calculating rates of reactions
The quantity of reactant or product can be measured by the mass in grams or by a volume in cm³.
- Describe how mass in grams can be used to follow a reaction that releases a gas.
- Describe how volume in cm³ can be used to follow a reaction that produces a gas.
- Choose and justify a suitable measurement method for a given reaction.
Calculating rates of reactions
The rate of a chemical reaction can be found by measuring the quantity of a reactant used or the quantity of product formed over time:
- Describe how to measure the rate of a reaction by following the loss of a reactant or the formation of a product over time.
- Calculate the average rate of a reaction over a stated time interval using the change in quantity and the time taken.
- Interpret a graph of quantity against time to determine the rate at a particular time from the gradient of a tangent (Higher Tier only).
Calculating rates of reactions
The units of rate of reaction may be given as g/s or cm³/s.
- Calculate the mean rate of a reaction from mass or gas volume data and give the unit as g/s or cm³/s.
- Select the appropriate unit for a rate of reaction by identifying whether mass or gas volume was measured.
- Explain why the unit of rate of reaction depends on the quantity measured and the time taken.
Cancer
Benign tumours are growths of abnormal cells which are contained in one area, usually within a membrane. They do not invade other parts of the body.
- Describe a benign tumour as a growth of abnormal cells contained in one area, usually within a membrane.
- Explain that benign tumours do not invade other parts of the body.
- Compare benign tumours with malignant tumours in terms of invasion and spread.
Cancer
Malignant tumour cells are cancers. They invade neighbouring tissues and spread to different parts of the body in the blood where they form secondary tumours.
- Describe malignant tumour cells as cancers that invade neighbouring tissues.
- Explain how malignant cells spread in the blood to form secondary tumours in other parts of the body.
- Distinguish malignant tumours from benign tumours by their invasion and spread.
Cancer
Scientists have identified lifestyle risk factors for various types of cancer. There are also genetic risk factors for some cancers.
- State that cancer involves uncontrolled cell division and tumour formation.
- Identify named lifestyle risk factors for cancer and describe how they raise risk.
- Describe genetic risk factors for some cancers and explain that they increase susceptibility rather than guarantee disease.
Cancer
Students should be able to describe cancer as the result of changes in cells that lead to uncontrolled growth and division.
- Describe cancer as the result of changes in cells that lead to uncontrolled growth and division.
- Explain how uncontrolled division produces a tumour and distinguish malignant from benign tumours.
- Relate named risk factors to an increased chance of the cell changes that lead to cancer.
Catalysts
A reaction profile for a catalysed reaction can be drawn in the following form:
- Draw a labelled reaction profile showing catalysed and uncatalysed pathways for a given reaction.
- Identify the activation energy on a reaction profile as the energy difference between reactants and the peak.
- Explain why a catalyst lowers the peak of a reaction profile without changing the overall energy change.
Catalysts
Catalysts change the rate of chemical reactions but are not used up during the reaction. Different reactions need different catalysts. Enzymes act as catalysts in biological systems.
- Describe what a catalyst does to the rate of a chemical reaction.
- Explain that a catalyst is not used up and can be recovered chemically unchanged.
- Give examples showing that different reactions need different catalysts, including enzymes in biological systems.
Catalysts
Catalysts increase the rate of reaction by providing a different pathway for the reaction that has a lower activation energy.
- Explain how a catalyst increases the rate of reaction by providing a different pathway with lower activation energy.
- Interpret an energy profile to compare catalysed and uncatalysed routes.
- State that a catalyst is not used up and does not change the overall energy change of the reaction.
Catalysts
Students should be able to explain catalytic action in terms of activation energy.
- Define activation energy as the minimum energy needed for a collision to result in reaction.
- Describe how a catalyst provides an alternative pathway with lower activation energy.
- Explain how a lower activation energy increases the rate by increasing the proportion of successful collisions.
Catalysts
Students should be able to identify catalysts in reactions from their effect on the rate of reaction and because they are not included in the chemical equation for the reaction.
- Identify a catalyst from rate data showing a faster reaction when it is present.
- Recognise a catalyst in a chemical equation because it is not included as a reactant or product.
- Explain why a catalyst can be recovered unchanged after a reaction.
Cell differentiation
As an organism develops, cells differentiate to form different types of cells.
- State that differentiation produces specialised cells as an organism develops.
- Describe how the structure of a named specialised cell relates to its function.
- Compare when differentiation occurs in animal and plant cells.
Cell differentiation
In mature animals, cell division is mainly restricted to repair and replacement. As a cell differentiates it acquires different sub-cellular structures to enable it to carry out a certain function. It has become a specialised cell.
- Describe that in mature animals cell division is mainly restricted to repair and replacement.
- Explain how differentiation leads to a cell acquiring sub-cellular structures suited to a certain function.
- Identify examples of specialised animal cells and relate their structures to their functions.
Cell differentiation
Many types of plant cells retain the ability to differentiate throughout life.
- State that many plant cells retain the ability to differentiate throughout life.
- Identify meristem regions such as root tips, shoot tips and cambium as sources of unspecialised plant cells.
- Explain how differentiation of plant cells produces specialised cells suited to particular functions.
Cell differentiation
Most types of animal cell differentiate at an early stage.
- Describe when most animal cells differentiate during development.
- Explain what happens to most animal cells after they differentiate.
- Compare animal cell differentiation with plant cell differentiation.
Cell differentiation
Students should be able to explain the importance of cell differentiation.
- Define cell differentiation and describe what happens during the process.
- Explain how differentiation allows cells to carry out specific functions.
- Relate differentiation to the formation of tissues, organs and organ systems.
Cell specialisation
Cells may be specialised to carry out a particular function:
- Define cell specialisation and state that it produces cells suited to particular functions.
- Describe how differentiation leads to specialised cells through gene expression.
- Explain how specific structural features of a named specialised cell increase its efficiency for a stated function.
Cell specialisation
root hair cells, xylem and phloem cells in plants.
- Describe the structure of root hair, xylem and phloem cells.
- Relate each cell's structure to its function in the plant.
- Compare xylem and phloem in terms of structure, living status and direction of transport.
Cell specialisation
sperm cells, nerve cells and muscle cells in animals
- Identify sperm, nerve and muscle cells and state their functions.
- Describe the structural adaptations of each cell type.
- Explain how each adaptation increases the cell's efficiency for its particular function.
Cell specialisation
Students should be able to, when provided with appropriate information, explain how the structure of different types of cell relate to their function in a tissue, an organ or organ system, or the whole organism.
- Describe the function of named specialised cells and identify their key structural features.
- Explain how each structural feature enables the cell to carry out its function.
- Apply information about cell structure to explain function at tissue, organ, organ system or whole-organism level.
Changes in energy
(assuming the limit of proportionality has not been exceeded)
- Define the limit of proportionality and explain its significance for Eₑ = ½ke².
- Identify the limit of proportionality from a force–extension graph.
- Recognise that the equation Eₑ = ½ke² cannot be used once the limit of proportionality is exceeded.
Changes in energy
E_p = m g h
- Recall and use the equation E_p = m g h.
- Rearrange the equation to calculate mass, gravitational field strength or height.
- Apply the equation to explain energy changes in lifting and falling objects.
Changes in energy
Eₑ = ½ke²
- Recall and apply the equation Eₑ = ½ke² to calculate elastic potential energy.
- Distinguish between extension and total length when using the equation.
- Convert between units of length and spring constant before substitution.
Changes in energy
Eₖ = ½mv²
- Recall and apply the equation Eₖ = ½mv² to calculate kinetic energy.
- Convert between units of mass and speed as required for the equation.
- Rearrange the equation to determine mass or speed when kinetic energy is known.
Changes in energy
elastic potential energy = 0.5 × spring constant × extension ²
- Apply the equation elastic potential energy = 0.5 × spring constant × extension² to numerical problems.
- Convert extension and spring constant into SI units and substitute them correctly.
- Explain the effect of changing the extension on the energy stored, using the squared relationship.
Changes in energy
elastic potential energy, E_e, in joules, J
- State that elastic potential energy is measured in joules, J, and is stored in stretched or compressed elastic objects.
- Apply the equation E_e = ½ k x² to calculate elastic potential energy using SI units.
- Explain how energy is transferred between elastic potential energy and other stores when an elastic object changes shape.
Changes in energy
extension, e, in metres, m
- Define extension as the change in length of a spring or elastic object and state its unit as metres.
- Calculate extension from original and stretched lengths, converting centimetres to metres correctly.
- Apply extension in the equation Ee = ½ke² with consistent SI units.
Changes in energy
g . p . e . = mass × gravitational f ield strength × height
- Recall and use the equation for gravitational potential energy.
- Apply the equation to calculate energy, mass, gravitational field strength or height.
- Explain how changes in mass, gravitational field strength or height affect the energy stored.
Changes in energy
gravitational field strength, g, in newtons per kilogram, N/kg (In any calculation the value of the gravitational field strength (g) will be given).
- Define gravitational field strength and state its unit as N/kg.
- Apply W = m × g and E_p = m × g × h using the value of g provided in a question.
- Explain how gravitational field strength differs between locations and affects weight but not mass.
Changes in energy
gravitational potential energy, E_p, in joules, J
- State that gravitational potential energy is measured in joules and depends on mass, gravitational field strength and vertical height.
- Calculate gravitational potential energy using E_p = m × g × h with consistent SI units.
- Describe energy transfers between gravitational, kinetic and thermal stores when an object is lifted or falls.
Changes in energy
height, h, in metres, m
- Identify the vertical height change from a diagram or description and express it in metres.
- Convert heights given in centimetres or kilometres into metres correctly.
- Substitute a height value into an energy equation and interpret the result in joules.
Changes in energy
kinetic energy = 0.5 × mass × speed ²
- Apply the equation kinetic energy = 0.5 × mass × speed² to calculate kinetic energy.
- Rearrange the equation to determine mass or speed from kinetic energy.
- Explain the effect of changing speed on kinetic energy using the squared relationship.
Changes in energy
kinetic energy, E_k, in joules, J
- Identify the symbol Eₖ and state that it represents kinetic energy.
- State that kinetic energy is measured in joules (J).
- Use the correct unit, J, in calculations and when describing kinetic energy.
Changes in energy
mass, m, in kilograms, kg
- Identify mass as a quantity measured in kilograms (kg).
- Convert between grams and kilograms accurately.
- Apply mass in kg correctly in energy equations such as E_k = ½mv² and E_p = mgh.
Changes in energy
speed, v, in metres per second, m/s
- Identify speed as a quantity measured in metres per second (m/s).
- Convert between km/h and m/s accurately.
- Apply speed in m/s correctly in the kinetic energy equation E_k = ½mv².
Changes in energy
spring constant, k, in newtons per metre, N/m
- Define the spring constant k and state its unit as newtons per metre, N/m.
- Determine k from the equation F = k x or from the gradient of a force-extension graph.
- Explain how the value of k relates to the stiffness of a spring and to the energy stored for a given extension.
Changes in energy
Students should be able to calculate the amount of energy associated with a moving object, a stretched spring and an object raised above ground level.
- Recall and apply E_k = ½mv², E_e = ½ke² and E_p = mgh to calculate energy in the named stores.
- Convert masses, lengths and speeds into consistent SI units before substituting into an equation.
- Rearrange each equation to determine an unknown mass, speed, spring constant, extension or height from a given energy value.
Changes in energy
The amount of elastic potential energy stored in a stretched spring can be calculated using the equation:
- Recall and write the equation for elastic potential energy stored in a stretched spring.
- Identify and convert the spring constant and extension into correct SI units before substitution.
- Apply the equation to calculate elastic potential energy for a spring stretched within its limit of proportionality.
Changes in energy
The amount of gravitational potential energy gained by an object raised above ground level can be calculated using the equation:
- Recall and apply the equation Ep = mgh to calculate gravitational potential energy gain.
- Use correct SI units for mass, gravitational field strength and height in calculations.
- Explain how lifting an object transfers energy to its gravitational potential energy store.
Changes in energy
The kinetic energy of a moving object can be calculated using the equation:
- State that kinetic energy is stored by a moving object and is measured in joules.
- Identify mass and speed as the variables that determine kinetic energy.
- Recall and use the equation Ek = 0.5 × m × v² correctly with SI units.
Changes of state
Changes of state are physical changes which differ from chemical changes because the material recovers its original properties if the change is reversed.
- Distinguish physical changes from chemical changes using properties before and after.
- Describe how reversing a change of state restores the original material and its properties.
- Justify a classification of a given change as physical or chemical using evidence.
Changes of state
Students should be able to describe how, when substances change state (melt, freeze, boil, evaporate, condense or sublimate), mass is conserved.
- Name and describe the six changes of state and identify the direction of each.
- Apply conservation of mass to a numerical example of a change of state.
- Explain apparent mass loss in an open system using the particle model.
Changes of state and specific latent heat
E = m L
- Use the equation E = m L to calculate energy, mass or specific latent heat.
- Rearrange E = m L correctly to make m or L the subject.
- Apply consistent SI units when substituting into E = m L.
Changes of state and specific latent heat
energy for a change of state = mass × specific latent heat
- Calculate the energy transferred during a change of state using energy = mass × specific latent heat.
- Explain why temperature remains constant during melting, boiling, freezing and condensing.
- Select and apply the specific latent heat of fusion or vaporisation to a given change of state.
Changes of state and specific latent heat
energy, E, in joules, J
- Define energy E and state its unit as the joule, J.
- Apply E = mL to calculate energy transferred during a change of state.
- Convert between joules and kilojoules accurately in written calculations.
Changes of state and specific latent heat
If a change of state happens:
- Describe what happens to temperature and energy during a change of state.
- Use ΔE = m L to calculate energy transferred during melting, boiling, condensing or freezing.
- Interpret heating and cooling curves to identify changes of state and temperature changes.
Changes of state and specific latent heat
mass, m, in kilograms, kg
- Define mass m and state its unit as the kilogram, kg.
- Convert masses between grams and kilograms accurately.
- Apply m = E ÷ L to calculate mass from energy and specific latent heat.
Changes of state and specific latent heat
Specific latent heat of fusion – change of state from solid to liquid
- Define specific latent heat of fusion and state its unit.
- Calculate the energy needed to melt a given mass of a solid using E = mL.
- Explain the melting process in terms of energy transfer and particle arrangement.
Changes of state and specific latent heat
Specific latent heat of vaporisation – change of state from liquid to vapour
- Define specific latent heat of vaporisation and state its unit.
- Calculate the energy transferred during vaporisation using E = m × Lv.
- Explain, using the particle model, why temperature remains constant during boiling.
Changes of state and specific latent heat
specific latent heat, L, in joules per kilogram, J/kg
- Define specific latent heat and state its unit as J/kg.
- Apply the equation E = mL to calculate energy, mass or specific latent heat.
- Explain why temperature remains constant during a change of state in terms of energy and particle behaviour.
Changes of state and specific latent heat
Students should be able to distinguish between specific heat capacity and specific latent heat.
- Define specific heat capacity and specific latent heat using the correct per-kilogram wording.
- Select and apply E = mcΔθ or E = mL correctly for a described heating or change-of-state process.
- Explain why temperature remains constant during a change of state in terms of energy and intermolecular bonds.
Changes of state and specific latent heat
Students should be able to interpret heating and cooling graphs that include changes of state.
- Identify sloping and flat sections on heating and cooling graphs and state what each represents.
- Label the melting, boiling, condensing and freezing points on a temperature–time graph.
- Explain why temperature remains constant during a change of state using the particle model.
Changes of state and specific latent heat
The energy needed for a substance to change state is called latent heat. When a change of state occurs, the energy supplied changes the energy stored (internal energy) but not the temperature.
- Define latent heat as the energy needed for a substance to change state at constant temperature.
- Explain why the temperature remains constant during a change of state in terms of internal energy and particle kinetic energy.
- Interpret heating curves to identify melting and boiling points and the flat sections where latent heat is absorbed.
Changes of state and specific latent heat
The specific latent heat of a substance is the amount of energy required to change the state of one kilogram of the substance with no change in temperature.
- State the definition of specific latent heat including the mass of one kilogram and constant temperature.
- Use the equation E = m × L to calculate energy, mass or specific latent heat, with correct unit conversions.
- Distinguish between specific latent heat of fusion and vaporisation and select the appropriate value for a given change of state.
Chemical bonds
Covalent bonding occurs in most non-metallic elements and in compounds of non-metals.
- Identify covalent bonding in a given substance by recognising that all the elements present are non-metals.
- Draw or complete a dot-and-cross diagram for a simple covalent molecule such as H₂O or CH₄.
- Explain how the number of shared pairs relates to the outer-shell electron configuration of the atoms involved.
Chemical bonds
Ionic bonding occurs in compounds formed from metals combined with non-metals.
- Identify from a formula or reaction whether a compound is likely to be ionic by checking for a metal combined with a non-metal.
- Draw or interpret a dot-and-cross diagram showing electron transfer and the resulting ions with correct charges.
- Explain at least one property of an ionic compound in terms of its giant lattice and electrostatic attraction.
Chemical bonds
Metallic bonding occurs in metallic elements and alloys.
- Describe the arrangement of positive ions and delocalised electrons in a metal.
- Explain how metallic bonding holds a metallic element or alloy together.
- Relate the structure of an alloy to its greater hardness compared with a pure metal.
Chemical bonds
Students should be able to explain chemical bonding in terms of electrostatic forces and the transfer or sharing of electrons.
- Describe how electrostatic forces produce chemical bonds.
- Distinguish between electron transfer in ionic bonding and electron sharing in covalent bonding.
- Explain the bonding in a named ionic compound, covalent molecule or metal using the correct particles and charges.
Chemical bonds
There are three types of strong chemical bonds: ionic, covalent and metallic. For ionic bonding the particles are oppositely charged ions. For covalent bonding the particles are atoms which share pairs of electrons. For metallic bonding the particles are atoms which share delocalised electrons.
- Identify a bond as ionic, covalent or metallic from a given formula or particle diagram.
- Describe the role of electrons in each of the three strong chemical bonds.
- Represent ionic and covalent bonding using dot-and-cross diagrams or ion symbols.
Chemical measurements
represent the distribution of results and make estimations of uncertainty
- Record repeated measurements and calculate their mean accurately.
- Determine the range and use half the range to estimate uncertainty.
- Construct and interpret a dot plot, tally chart or histogram showing the distribution of results.
Chemical measurements
use the range of a set of measurements about the mean as a measure of uncertainty.
- Calculate the range of a set of repeated measurements.
- Use half the range to estimate and quote the uncertainty of a mean value.
- Explain how the size of the range affects confidence in a measured result.
Chemical measurements
Whenever a measurement is made there is always some uncertainty about the result obtained.
- Estimate the uncertainty of a reading from the smallest scale division of the instrument used, distinguishing between analogue and digital scales.
- Explain why repeating a measurement and taking a mean reduces random variation but not systematic error.
- Report a measurement with an appropriate uncertainty and a justified number of significant figures.
Chromatography
Chromatography can be used to separate mixtures and can give information to help identify substances. Chromatography involves a stationary phase and a mobile phase. Separation depends on the distribution of substances between the phases.
- Describe chromatography as a separation technique involving a stationary phase and a mobile phase.
- Explain how differences in distribution between the phases cause components of a mixture to separate.
- Calculate and use Rf values to help identify substances from a chromatogram.
Chromatography
Different compounds have different R_f values in different solvents, which can be used to help identify the compounds. The compounds in a mixture may separate into different spots depending on the solvent but a pure compound will produce a single spot in all solvents.
- Explain why a compound can have different R_f values in different solvents.
- Describe how the number of spots relates to whether a sample is pure or a mixture.
- Compare chromatograms of an unknown sample with a known pure sample to support identification.
Chromatography
distaₙce moved by solveₙt
- Measure the distance moved by the solvent front and by a solute from the pencil baseline.
- Calculate an R_f value using the correct distances and no units.
- Explain why the baseline is drawn in pencil and why the solvent front must be marked promptly.
Chromatography
explain how paper chromatography separates mixtures
- Explain the roles of the mobile and stationary phases in paper chromatography.
- Relate the distance moved by a component to its solubility and attraction to the paper.
- Use chromatographic results to identify components of a mixture.
Chromatography
interpret chromatograms and determine R_f values from chromatograms
- Measure the distance moved by a substance and by the solvent front from the start line.
- Calculate R_f values using the correct formula and give them without units.
- Interpret chromatograms to identify substances and to deduce the number of substances in a mixture.
Chromatography
provide answers to an appropriate number of significant figures.
- Identify the number of significant figures in a measured or calculated value.
- Calculate an R_f value and round it to an appropriate number of significant figures.
- Justify the number of significant figures used in a chromatography answer.
Chromatography
R_f = distance moved by substance / distance moved by solvent
- Apply the equation R_f = distance moved by substance ÷ distance moved by solvent to measured distances.
- Interpret an R_f value as a unitless ratio between 0 and 1.
- Rearrange the equation to calculate a missing distance from a known R_f value.
Chromatography
Required practical activity 12: investigate how paper chromatography can be used to separate and tell the difference between coloured substances. Students should calculate R_f values.
- Carry out paper chromatography to separate coloured substances and record the chromatogram accurately.
- Calculate R_f values from measured distances and use them to compare coloured substances.
- Explain how chromatography can tell the difference between pure substances and mixtures.
Chromatography
suggest how chromatographic methods can be used for distinguishing pure substances from impure substances
- Describe how a chromatogram can show whether a substance is pure or impure.
- Explain why a pure substance gives one spot and an impure substance gives more than one spot.
- Compare a sample with a pure reference run under the same conditions to decide whether the sample is pure.
Chromatography
The ratio of the distance moved by a compound (centre of spot from origin) to the distance moved by the solvent can be expressed as its R_f value:
- Measure the distance moved by the solvent front and by the centre of a spot from the origin line.
- Calculate an R_f value by dividing the distance moved by the substance by the distance moved by the solvent.
- Use R_f values from the same chromatogram to identify an unknown compound by comparison with a reference.
Chromosomes
In body cells the chromosomes are normally found in pairs.
- State that body cells normally contain chromosomes in pairs.
- Explain that one chromosome of each pair is inherited from each parent.
- Distinguish diploid body cells from haploid gametes.
Chromosomes
The nucleus of a cell contains chromosomes made of DNA molecules. Each chromosome carries a large number of genes.
- State that the nucleus contains chromosomes made of DNA molecules.
- Describe a gene as a section of DNA that codes for a protein.
- Explain that each chromosome carries a large number of genes.
Classification of living organisms
Archaea (primitive bacteria usually living in extreme environments)
- State that archaea are prokaryotes forming a domain separate from bacteria.
- Describe how archaea differ from true bacteria in cell chemistry and ribosomes.
- Give examples of extreme and non-extreme environments where archaea are found.
Classification of living organisms
As evidence of internal structures became more developed due to improvements in microscopes, and the understanding of biochemical processes progressed, new models of classification were proposed.
- Describe how improvements in microscopes allowed internal structures to be observed.
- Explain how biochemical evidence contributed to changes in classification.
- Relate new evidence to the proposal of new classification models.
Classification of living organisms
Bacteria (true bacteria)
- Describe the structure of a bacterial cell as a prokaryote.
- Explain how bacterial structure differs from that of eukaryotic cells.
- State that bacteria form a domain separate from Archaea and Eukaryota.
Classification of living organisms
Due to evidence available from chemical analysis there is now a ‘three-domain system’ developed by Carl Woese. In this system organisms are divided into:
- Name the three domains in Woese’s system.
- Describe the evidence from chemical analysis that supports the three-domain system.
- Distinguish between prokaryotic domains and the eukaryotic domain.
Classification of living organisms
Eukaryota (which includes protists, fungi, plants and animals).
- Define Eukaryota by the presence of a true nucleus and membrane-bound organelles.
- List the four included groups: protists, fungi, plants and animals.
- Classify a named organism as eukaryotic using its cell structure.
Classification of living organisms
Evolutionary trees are a method used by scientists to show how they believe organisms are related. They use current classification data for living organisms and fossil data for extinct organisms.
- Describe what an evolutionary tree represents.
- Identify the two main sources of evidence used to construct evolutionary trees.
- Explain why evolutionary trees may change as new evidence is discovered.
Classification of living organisms
Linnaeus classified living things into kingdom, phylum, class, order, family, genus and species. Organisms are named by the binomial system of genus and species.
- List the seven levels of the Linnaean classification system in order.
- Write a scientific name correctly using the binomial system.
- Explain why the binomial system is useful for scientists.
Classification of living organisms
Students should be able to describe the impact of developments in biology on classification systems.
- Describe how microscopy and molecular data changed classification systems.
- Explain why the three-domain system was introduced above the kingdom level.
- Use DNA or protein sequence data to justify a change in the classification of an organism.
Classification of living organisms
Students should be able to use information given to show understanding of the Linnaean system.
- Order the Linnaean ranks from kingdom to species.
- Assign an organism to a named group using features supplied in a table or key.
- Explain how nested groups show increasing similarity from kingdom to species.
Classification of living organisms
Traditionally living things have been classified into groups depending on their structure and characteristics in a system developed by Carl Linnaeus.
- State that living things are classified into groups based on structure and characteristics.
- Identify Carl Linnaeus as the scientist who developed the traditional classification system.
- Give examples of structural characteristics used to group organisms.
Collision theory and activation energy
Collision theory explains how various factors affect rates of reactions. According to this theory, chemical reactions can occur only when reacting particles collide with each other and with sufficient energy. The minimum amount of energy that particles must have to react is called the activation energy.
- Describe collision theory and the conditions needed for a successful collision.
- Define activation energy and use it to explain why some collisions do not lead to reaction.
- Apply collision theory to explain how concentration, temperature, surface area, pressure and catalysts affect reaction rate.
Collision theory and activation energy
Increasing the concentration of reactants in solution, the pressure of reacting gases, and the surface area of solid reactants increases the frequency of collisions and so increases the rate of reaction.
- Describe how concentration, pressure and surface area affect the rate of a reaction.
- Explain the effect of each factor in terms of collision frequency.
- Apply collision theory to a named practical example involving a solution, a gas or a solid.
Collision theory and activation energy
Increasing the temperature increases the frequency of collisions and makes the collisions more energetic, and so increases the rate of reaction.
- Describe how temperature affects the rate of a reaction.
- Explain the effect of temperature using collision frequency and collision energy.
- Interpret rate data from a temperature-based practical, such as the sodium thiosulfate cross method.
Collision theory and activation energy
predict and explain the effects of changes in the size of pieces of a reacting solid in terms of surface area to volume ratio
- Describe how breaking a solid into smaller pieces changes its surface area to volume ratio.
- Explain, using collision theory, why a greater surface area to volume ratio increases the rate of reaction.
- Predict and justify the effect of changing the size of pieces of a reacting solid on the rate and on the total product formed.
Collision theory and activation energy
predict and explain using collision theory the effects of changing conditions of concentration, pressure and temperature on the rate of a reaction
- Predict the direction of rate change when concentration, pressure or temperature is altered.
- Explain each predicted change using collision frequency and activation energy.
- Apply collision theory consistently to unfamiliar reactions and practical contexts.
Collision theory and activation energy
use simple ideas about proportionality when using collision theory to explain the effect of a factor on the rate of a reaction.
- Describe how collision theory links successful collision frequency to the rate of a reaction.
- Apply simple proportionality to predict how changing concentration, pressure or surface area affects the rate.
- Explain why proportional predictions are approximate and depend on controlling other variables.
Communicable (infectious) diseases
Bacteria and viruses may reproduce rapidly inside the body.
- Describe how bacteria reproduce by binary fission inside the body.
- Explain why viruses must use a host cell to replicate.
- Relate rapid pathogen reproduction to the development of symptoms.
Communicable (infectious) diseases
Bacteria may produce poisons (toxins) that damage tissues and make us feel ill.
- Describe how bacterial toxins damage tissues and cause illness.
- Explain why symptoms can occur away from the site of a bacterial infection.
- Distinguish between harm caused by toxins and harm caused by bacterial growth.
Communicable (infectious) diseases
Pathogens are microorganisms that cause infectious disease. Pathogens may be viruses, bacteria, protists or fungi. They may infect plants or animals and can be spread by direct contact, by water or by air.
- Define pathogen and name the four main pathogen groups.
- Give examples of pathogens that infect plants and animals.
- Describe direct contact, water and air as routes of pathogen spread.
Communicable (infectious) diseases
Students should be able to explain how diseases caused by viruses, bacteria, protists and fungi are spread in animals and plants.
- Name the four pathogen groups and give an example disease for each.
- Explain the main transmission routes for viral, bacterial, protist and fungal diseases in animals.
- Explain the main transmission routes for viral, bacterial, protist and fungal diseases in plants.
Communicable (infectious) diseases
Students should be able to explain how the spread of diseases can be reduced or prevented.
- Describe how direct contact, water, air, food and vectors spread pathogens.
- Explain how named control methods interrupt specific transmission routes.
- Apply the chain-of-infection model to suggest how an outbreak could be reduced.
Communicable (infectious) diseases
Viruses live and reproduce inside cells, causing cell damage.
- State that viruses reproduce inside living cells.
- Describe how viral replication damages host cells.
- Explain why viral infections cause symptoms and why antibiotics are ineffective.
Communities
An ecosystem is the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment.
- Define an ecosystem and distinguish it from a community and a population.
- Classify factors as biotic or abiotic and give examples of each.
- Explain how interactions between biotic and abiotic components affect the organisms in an ecosystem.
Communities
different levels of organisation in an ecosystem from individual organisms to the whole ecosystem
- State the ecological levels from individual organism to whole ecosystem in the correct order.
- Classify a given example, such as all the frogs in a pond or a woodland with its soil and climate, at the correct level.
- Explain how each level includes the previous level and what is added at the ecosystem stage.
Communities
Plants in a community or habitat often compete with each other for light and space, and for water and mineral ions from the soil. Animals often compete with each other for food, mates and territory.
- List the resources plants and animals compete for in a named habitat.
- Distinguish between intraspecific and interspecific competition with an example of each.
- Explain how the outcome of competition affects which organisms survive and reproduce.
Communities
Students should be able to describe:
- Define levels of organisation from individual organisms to whole ecosystems.
- Describe what plants and animals compete for in a community.
- Explain interdependence and the concept of a stable community.
Communities
Students should be able to extract and interpret information from charts, graphs and tables relating to the interaction of organisms within a community.
- Extract specific values and trends from charts, graphs and tables about organisms in a community.
- Interpret predator-prey and other interaction data to explain how one population affects another.
- Use data as evidence to support conclusions about interdependence within a community.
Communities
Students should be able to, when provided with appropriate information:
- Extract relevant numerical or descriptive information from a table, graph or passage about a community.
- Describe patterns and trends in the supplied information using correct units and comparative language.
- Relate observations from the resource to ecological processes such as competition, predation or interdependence.
Communities
suggest how organisms are adapted to the conditions in which they live.
- Identify the key conditions of a named habitat that affect organisms.
- Describe structural, behavioural and physiological adaptations and link each to a survival advantage.
- Explain how an adaptation increases an organism's chance of surviving and reproducing in its environment.
Communities
suggest the factors for which organisms are competing in a given habitat
- Identify the resources that plants and animals compete for in a described habitat.
- Justify a suggested competitive factor using evidence from the habitat description.
- Distinguish between competition for different resources and explain why the resource is limiting.
Communities
the importance of interdependence and competition in a community.
- Define interdependence and competition using correct ecological terms.
- Give named examples of resources that plants and animals compete for.
- Explain how a change in one population can affect other populations through interdependence and competition.
Communities
To survive and reproduce, organisms require a supply of materials from their surroundings and from the other living organisms there.
- State the materials plants obtain from air and soil and the materials animals obtain from food.
- Explain how decomposers recycle mineral ions to the soil and carbon dioxide to the atmosphere.
- Link an insufficient supply of materials to reduced survival or reproduction in a named organism.
Communities
Within a community each species depends on other species for food, shelter, pollination, seed dispersal etc. If one species is removed it can affect the whole community. This is called interdependence. A stable community is one where all the species and environmental factors are in balance so that population sizes remain fairly constant.
- Define community and interdependence, and give named examples of species depending on each other for food, shelter, pollination or seed dispersal.
- Predict and explain how removing one species can affect other populations in the community.
- Describe the features of a stable community and explain why population sizes remain fairly constant.
Concentration of solutions
(HT only) explain how the mass of a solute and the volume of a solution is related to the concentration of the solution.
- Describe how concentration depends on both the mass of solute and the volume of solution.
- Explain the direct and inverse proportionalities using the concentration equation.
- Apply proportional reasoning to predict how concentration changes when mass or volume is altered.
Concentration of solutions
calculate the mass of solute in a given volume of solution of known concentration in terms of mass per given volume of solution
- Select and rearrange the concentration relationship to make mass the subject.
- Convert volumes between cm³ and dm³ correctly before calculation.
- Calculate the mass of solute in a solution of known concentration and volume, giving the answer with an appropriate unit.
Concentration of solutions
Many chemical reactions take place in solutions. The concentration of a solution can be measured in mass per given volume of solution, eg grams per dm³ (g/dm³).
- Define concentration as the mass of solute per given volume of solution.
- Convert a volume in cm³ to dm³ correctly.
- Calculate concentration in g/dm³ from supplied mass and volume values.
Conservation of mass and balanced chemical equations
Students should understand the use of the multipliers in equations in normal script before a formula and in subscript within a formula.
- State the meaning of a subscript within a chemical formula and a normal-script multiplier before a formula.
- Count the total number of each type of atom in a formula that includes both subscripts and a front multiplier.
- Balance a given chemical equation by adjusting normal-script multipliers only, leaving all formulae unchanged.
Conservation of mass and balanced chemical equations
The law of conservation of mass states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants.
- State the law of conservation of mass in terms of atoms.
- Use the law to calculate an unknown mass in a reaction.
- Explain why mass appears to change when a gas escapes or enters.
Conservation of mass and balanced chemical equations
This means that chemical reactions can be represented by symbol equations which are balanced in terms of the numbers of atoms of each element involved on both sides of the equation.
- Write a balanced symbol equation from given formulae.
- Explain why an equation must be balanced in terms of atoms.
- Use a balanced equation to state the ratio in which substances react.
Conservation of momentum
In a closed system, the total momentum before an event is equal to the total momentum after the event.
- State the principle of conservation of momentum for a closed system.
- Calculate total momentum before and after an interaction using p = m × v.
- Use conservation of momentum to find an unknown velocity or mass in a collision or explosion.
Conservation of momentum
Students should be able to use the concept of momentum as a model to describe and explain examples of momentum in an event, such as a collision.
- Describe a collision using masses, velocities and directions.
- Calculate total momentum before and after an event.
- Explain recoil and explosions using the conservation of momentum.
Conservation of momentum
This is called conservation of momentum.
- State the principle of conservation of momentum for a closed system.
- Calculate total momentum before and after a collision or explosion.
- Explain a recoil or collision using conservation of momentum and direction.
Contact and non-contact forces
A force is a push or pull that acts on an object due to the interaction with another object. All forces between objects are either:
- Define a force as a push or pull due to interaction with another object.
- Distinguish contact forces from non-contact forces and give examples of each.
- Classify a named force by identifying the interacting objects and whether they touch.
Contact and non-contact forces
contact forces – the objects are physically touching
- Define a contact force as one that acts only when objects are physically touching.
- Classify given forces as contact or non-contact using the touching criterion.
- Represent a contact force correctly on a free-body diagram at the point of contact.
Contact and non-contact forces
Examples of contact forces include friction, air resistance, tension and normal contact force.
- Identify friction, air resistance, tension and normal contact force as contact forces in given situations.
- Describe the direction and effect of each named contact force.
- Explain why each named force cannot act without contact between objects or surfaces.
Contact and non-contact forces
Examples of non-contact forces are gravitational force, electrostatic force and magnetic force.
- Identify gravitational, electrostatic and magnetic forces as non-contact forces.
- Describe the conditions under which each non-contact force attracts or repels.
- Explain how non-contact forces act at a distance and change with separation.
Contact and non-contact forces
Force is a vector quantity.
- Define a vector quantity and identify force as an example.
- Represent forces as arrows with correct relative lengths and directions.
- Calculate the resultant of forces acting along the same line, including its direction.
Contact and non-contact forces
non-contact forces – the objects are physically separated.
- Define a non-contact force as one that acts between objects that are physically separated.
- Classify given forces as non-contact using the separation criterion.
- Explain everyday examples of non-contact forces such as gravity, electrostatic attraction and magnetic attraction.
Contact and non-contact forces
Students should be able to describe the interaction between pairs of objects which produce a force on each object. The forces to be represented as vectors.
- Describe the paired forces in a given contact or non-contact interaction.
- Draw vector arrows for each force in the pair with correct direction and relative magnitude.
- Explain why paired forces acting on different objects do not cancel each other.
Contraception
abstaining from intercourse when an egg may be in the oviduct
- Describe how abstaining during the fertile period can prevent pregnancy.
- Explain why predicting ovulation is difficult and affects reliability.
- State that this method gives no protection against sexually transmitted infections.
Contraception
barrier methods such as condoms and diaphragms which prevent the sperm reaching an egg
- Describe how condoms and diaphragms act as physical barriers to sperm.
- Explain why correct and consistent use is needed for barrier methods to be effective.
- Compare barrier methods with hormonal contraception in terms of how they prevent pregnancy.
Contraception
Fertility can be controlled by a variety of hormonal and non- hormonal methods of contraception.
- Describe how hormonal contraceptives alter the menstrual cycle to prevent pregnancy.
- Describe non-hormonal methods of contraception, including abstaining from intercourse when an egg may be in the oviduct.
- Compare hormonal and non-hormonal methods in terms of effectiveness, side effects and protection against sexually transmitted infections.
Contraception
injection, implant or skin patch of slow release progesterone to inhibit the maturation and release of eggs for a number of months or years
- Identify injection, implant and skin patch as slow-release progesterone methods.
- Explain how progesterone inhibits the maturation and release of eggs.
- Relate the slow-release delivery to the duration of contraceptive cover.
Contraception
intrauterine devices which prevent the implantation of an embryo or release a hormone
- Describe how intrauterine devices prevent pregnancy.
- Explain the difference between copper and hormonal intrauterine devices.
- Compare intrauterine devices with barrier methods in terms of when and how they act.
Contraception
oral contraceptives that contain hormones to inhibit FSH production so that no eggs mature
- State that oral contraceptives contain hormones that reduce FSH production.
- Explain how reduced FSH prevents a follicle and egg from maturing.
- Link the absence of a mature egg to the prevention of fertilisation.
Contraception
spermicidal agents which kill or disable sperm
- Describe how spermicidal agents prevent pregnancy by killing or disabling sperm.
- Explain why spermicides are often used together with a barrier method.
- State that spermicides do not protect against sexually transmitted infections.
Contraception
Students should be able to evaluate the different hormonal and non-hormonal methods of contraception.
- Distinguish hormonal from non-hormonal contraceptive methods and describe how each works.
- Compare methods using criteria such as effectiveness, side effects, reversibility and STI protection.
- Reach and justify a conclusion about the most suitable method for a described situation.
Contraception
surgical methods of male and female sterilisation.
- Describe how male sterilisation blocks the vas deferens to prevent sperm leaving the body.
- Describe how female sterilisation blocks the oviducts to prevent the egg and sperm meeting.
- Explain why sterilisation is a permanent method that does not protect against sexually transmitted infections.
Contraception
These include:
- Name hormonal and non-hormonal methods of contraception.
- Classify named methods as hormonal or non-hormonal, recognising that IUDs can be either.
- State the mechanism by which each named method prevents pregnancy.
Control of blood glucose concentration
(HT only) If the blood glucose concentration is too low, the pancreas produces the hormone glucagon that causes glycogen to be converted into glucose and released into the blood.
- Describe the role of glucagon when blood glucose concentration is too low.
- Explain how glucagon causes glycogen to be converted into glucose and released into the blood.
- Distinguish between the actions of insulin and glucagon in controlling blood glucose.
Control of blood glucose concentration
(HT only) Students should be able to explain how glucagon interacts with insulin in a negative feedback cycle to control blood glucose (sugar) levels in the body.
- State the gland that secretes insulin and glucagon and the conditions that trigger each.
- Describe the effects of insulin on liver and muscle cells, and the effect of glucagon on liver cells.
- Explain how the opposing actions of insulin and glucagon form a negative feedback cycle that stabilises blood glucose.
Control of blood glucose concentration
Blood glucose concentration is monitored and controlled by the pancreas.
- State that the pancreas monitors blood glucose concentration.
- Describe how the pancreas controls blood glucose using hormones.
- Explain why blood glucose concentration must be kept within a narrow range.
Control of blood glucose concentration
If the blood glucose concentration is too high, the pancreas produces the hormone insulin that causes glucose to move from the blood into the cells. In liver and muscle cells excess glucose is converted to glycogen for storage.
- Describe how insulin lowers blood glucose concentration.
- Explain the role of liver and muscle cells in converting excess glucose to glycogen.
- Relate the insulin response to the principle of negative feedback.
Control of blood glucose concentration
In Type 2 diabetes the body cells no longer respond to insulin produced by the pancreas. A carbohydrate controlled diet and an exercise regime are common treatments. Obesity is a risk factor for Type 2 diabetes.
- Describe how body cells respond to insulin in Type 2 diabetes.
- Explain how a carbohydrate-controlled diet and exercise regime help manage Type 2 diabetes.
- Explain why obesity is a risk factor for Type 2 diabetes.
Control of blood glucose concentration
Students should be able to compare Type 1 and Type 2 diabetes and explain how they can be treated.
- Compare the causes of Type 1 and Type 2 diabetes.
- Explain how Type 1 and Type 2 diabetes are treated.
- Distinguish between the roles of insulin production and insulin response in the two types of diabetes.
Control of blood glucose concentration
Students should be able to explain how insulin controls blood glucose (sugar) levels in the body.
- Describe the role of the pancreas in detecting changes in blood glucose concentration.
- Explain how insulin increases glucose uptake and glycogen storage in target cells.
- Use the idea of negative feedback to explain how blood glucose concentration is returned towards its normal level.
Control of blood glucose concentration
Students should be able to extract information and interpret data from graphs that show the effect of insulin in blood glucose levels in both people with diabetes and people without diabetes.
- Read values of blood glucose concentration and time from a graph showing insulin effects.
- Compare the blood glucose patterns of a person with diabetes and a person without diabetes using quoted data.
- Explain how the shape of a graph links to the action of insulin in lowering blood glucose.
Control of blood glucose concentration
Type 1 diabetes is a disorder in which the pancreas fails to produce sufficient insulin. It is characterised by uncontrolled high blood glucose levels and is normally treated with insulin injections.
- State that type 1 diabetes results from the pancreas failing to produce sufficient insulin.
- Describe the characteristic uncontrolled high blood glucose levels and associated symptoms of type 1 diabetes.
- Explain why insulin injections are the normal treatment for type 1 diabetes.
Coronary heart disease: a non-communicable disease
In coronary heart disease layers of fatty material build up inside the coronary arteries, narrowing them. This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle. Stents are used to keep the coronary arteries open. Statins are widely used to reduce blood cholesterol levels which slows down the rate of fatty material deposit.
- Describe how fatty material builds up in the coronary arteries and narrows them.
- Explain how reduced coronary blood flow leads to a lack of oxygen for the heart muscle.
- Compare stents and statins in terms of how they reduce the effects of coronary heart disease.
Coronary heart disease: a non-communicable disease
In some people heart valves may become faulty, preventing the valve from opening fully, or the heart valve might develop a leak. Students should understand the consequences of faulty valves. Faulty heart valves can be replaced using biological or mechanical valves.
- Describe how a faulty heart valve can fail to open fully or can leak.
- Explain the consequences of faulty valves for blood flow and heart function.
- Compare biological and mechanical replacement valves.
Coronary heart disease: a non-communicable disease
In the case of heart failure a donor heart, or heart and lungs can be transplanted. Artificial hearts are occasionally used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to rest as an aid to recovery.
- Describe what is meant by heart failure and how it affects blood pumping.
- Describe donor heart and heart-lung transplantation as treatments for heart failure.
- Explain how and why artificial hearts are used whilst waiting for a transplant or to rest the heart.
Coronary heart disease: a non-communicable disease
Students should be able to evaluate the advantages and disadvantages of treating cardiovascular diseases by drugs, mechanical devices or transplant.
- Describe how drugs, mechanical devices and transplants are used to treat cardiovascular diseases.
- Compare the advantages and disadvantages of each treatment option using appropriate criteria.
- Reach and justify a conclusion about the most suitable treatment for a given patient.
Covalent bonding
Covalently bonded substances may consist of small molecules.
- Recognise that some covalently bonded substances exist as small, discrete molecules.
- Distinguish between strong covalent bonds within a molecule and weak forces between molecules.
- Relate the small-molecule structure of a substance to its low melting point and boiling point.
Covalent bonding
deduce the molecular formula of a substance from a given model or diagram in these forms showing the atoms and bonds in the molecule.
- Identify the elements present in a molecular model or diagram.
- Count the atoms of each element in one molecule accurately.
- Write the molecular formula using correct symbols and subscripts.
Covalent bonding
describe the limitations of using dot and cross, ball and stick, two and three-dimensional diagrams to represent molecules or giant structures
- State one limitation of dot and cross diagrams for showing molecular shape or atom size.
- Explain why ball and stick models do not show the true size of atoms or the empty space between them.
- Compare two-dimensional and three-dimensional diagrams in terms of how well they show the arrangement of atoms in a giant structure.
Covalent bonding
draw dot and cross diagrams for the molecules of hydrogen, chlorine, oxygen, nitrogen, hydrogen chloride, water, ammonia and methane
- Draw accurate dot and cross diagrams for hydrogen, chlorine, oxygen, nitrogen, hydrogen chloride, water, ammonia and methane.
- Distinguish between bonding pairs and lone pairs in each of the eight molecules.
- Use dot and cross diagrams to show how each atom achieves a full outer shell.
Covalent bonding
Polymers can be represented in the form:
- Draw the shorthand representation of a polymer from a given monomer.
- Identify the repeating unit and the meaning of n in a polymer structure.
- Explain how the shorthand representation shows many monomer units joined by covalent bonds.
Covalent bonding
represent the covalent bonds in small molecules, in the repeating units of polymers and in part of giant covalent structures, using a line to represent a single bond
- Draw small molecules such as H₂O, CH₄ and CO₂ with one line for each shared pair of electrons.
- Draw the repeating unit of a polymer with bonds crossing the brackets and n outside.
- Draw a labelled fragment of diamond, graphite or silicon dioxide showing the correct number of lines around each atom.
Covalent bonding
Some covalently bonded substances have giant covalent structures, such as diamond and silicon dioxide.
- Describe the giant covalent structures of diamond and silicon dioxide.
- Explain how the network of strong covalent bonds leads to high melting points.
- Explain why giant covalent substances such as diamond and silicon dioxide do not conduct electricity.
Covalent bonding
Some covalently bonded substances have very large molecules, such as polymers.
- Describe polymers as covalently bonded substances containing very large molecules built from repeating monomer units.
- Recognise a polymer from a formula that shows a repeating unit or the subscript n.
- Compare the structure and properties of polymers with those of small-molecule covalent substances, focusing on intermolecular forces.
Covalent bonding
Students should be able to recognise common substances that consist of small molecules from their chemical formula.
- Identify the elements present in a given chemical formula and classify each as a metal or non-metal.
- Recognise common small-molecule substances such as H₂O, CO₂, NH₃, CH₄, O₂, N₂, HCl, Cl₂ and C₆H₁₂O₆ from their formulae.
- Distinguish small molecules from ionic compounds, polymers, and giant covalent structures using formula and composition.
Covalent bonding
The covalent bonds in molecules and giant structures can be represented in the following forms:
- Draw dot-and-cross diagrams for simple covalent molecules.
- Write displayed and structural formulae for simple covalent molecules.
- Represent the bonding in a giant covalent structure using a 3D ball-and-stick model of a section of the network.
Covalent bonding
When atoms share pairs of electrons, they form covalent bonds. These bonds between atoms are strong.
- Describe covalent bonding as the sharing of pairs of electrons between atoms.
- Represent simple covalent bonds using dot-and-cross diagrams and displayed formulae.
- Explain why a covalent bond is strong in terms of attraction between the shared electrons and the nuclei.
Covalent bonding
where n is a large number.
- State that n represents a large number of repeating units.
- Explain how the value of n relates to the length and properties of a polymer chain.
- Interpret polymer formulae containing n and describe what the brackets and n show.
Cracking and alkenes
Alkenes are more reactive than alkanes and react with bromine water, which is used as a test for alkenes.
- Describe the bromine water test for alkenes, including the colour change.
- Explain why alkenes react with bromine water but alkanes do not.
- Use the test to distinguish an alkene from an alkane.
Cracking and alkenes
Alkenes are used to produce polymers and as starting materials for the production of many other chemicals.
- State that alkenes are unsaturated hydrocarbons containing a C=C double bond.
- Identify the molecular and empirical formulae of simple alkenes like ethene.
- Explain that alkenes are used to produce polymers and as starting materials to produce other chemicals.
Cracking and alkenes
Cracking can be done by various methods including catalytic cracking and steam cracking.
- State that cracking breaks large hydrocarbon molecules into smaller ones.
- Identify catalytic cracking and steam cracking as two methods of cracking.
- Describe the products of cracking as shorter alkanes and alkenes.
Cracking and alkenes
Hydrocarbons can be broken down (cracked) to produce smaller, more useful molecules.
- Describe cracking as a thermal decomposition reaction that breaks large hydrocarbons into smaller molecules.
- Identify the products of cracking as smaller alkanes and alkenes, and recognise the C=C double bond in alkenes.
- Explain why cracking is economically important for producing useful fuels and polymer feedstocks.
Cracking and alkenes
Students should be able to balance chemical equations as examples of cracking given the formulae of the reactants and products.
- Write correct formulae for the reactants and products in a cracking reaction.
- Balance a cracking equation by adding whole-number coefficients without changing formulae.
- Check a balanced cracking equation by counting carbon and hydrogen atoms on each side.
Cracking and alkenes
Students should be able to describe in general terms the conditions used for catalytic cracking and steam cracking.
- Describe the general conditions for catalytic cracking, including a hot catalyst and high temperature.
- Describe the general conditions for steam cracking, including steam and high temperature without a catalyst.
- Compare the two cracking methods by identifying the key difference in their conditions.
Cracking and alkenes
Students should be able to give examples to illustrate the usefulness of cracking. They should also be able to explain how modern life depends on the uses of hydrocarbons.
- Give at least one example of cracking and identify the useful products formed.
- Explain how cracking increases the supply of short-chain fuels and reactive alkenes.
- Describe how modern life depends on hydrocarbons for fuels and for making everyday materials.
Cracking and alkenes
Students should be able to recall the colour change when bromine water reacts with an alkene.
- State the colour of bromine water before and after reaction with an alkene.
- Describe the test procedure of adding bromine water and shaking.
- Use the result to classify a hydrocarbon as an alkene or an alkane.
Cracking and alkenes
The products of cracking include alkanes and another type of hydrocarbon called alkenes.
- State that cracking produces a mixture of smaller hydrocarbons including alkanes and alkenes.
- Identify an alkane and an alkene from a given name or formula.
- Explain why cracking is useful in the petrochemical industry.
Cracking and alkenes
There is a high demand for fuels with small molecules and so some of the products of cracking are useful as fuels.
- Explain why small hydrocarbon molecules are useful as fuels.
- Describe how cracking produces smaller molecules from larger ones.
- Relate the products of cracking to their uses as fuels and as feedstocks for polymers.
Crude oil, hydrocarbons and alkanes
Alkane molecules can be represented in the following forms:
- Draw and interpret displayed, structural and molecular formulae for simple alkanes.
- Convert between different representations of the same alkane molecule.
- Explain why different representations can describe the same substance.
Crude oil, hydrocarbons and alkanes
C₂H₆ or
- Identify C₂H₆ as ethane and state the number of each type of atom present.
- Describe the single covalent bonding in an ethane molecule.
- Relate the molecular formula of ethane to the alkane general formula.
Crude oil, hydrocarbons and alkanes
Crude oil is a finite resource found in rocks. Crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried in mud.
- State that crude oil is a finite resource found in rocks.
- Describe how crude oil formed from ancient plankton buried in mud.
- Explain why crude oil is classified as non-renewable.
Crude oil, hydrocarbons and alkanes
Crude oil is a mixture of a very large number of compounds. Most of the compounds in crude oil are hydrocarbons, which are molecules made up of hydrogen and carbon atoms only.
- Describe crude oil as a mixture of a very large number of compounds.
- Define a hydrocarbon as a molecule made of carbon and hydrogen atoms only.
- Identify whether a given formula represents a hydrocarbon.
Crude oil, hydrocarbons and alkanes
Most of the hydrocarbons in crude oil are hydrocarbons called alkanes. The general formula for the homologous series of alkanes is CₙH₂ₙ₊₂
- State that most hydrocarbons in crude oil are alkanes.
- Apply the general formula CₙH₂ₙ₊₂ to deduce the formula of an alkane from its carbon number.
- Explain that alkanes are a homologous series of saturated hydrocarbons.
Crude oil, hydrocarbons and alkanes
Students should be able to recognise substances as alkanes given their formulae in these forms.
- Identify a molecular formula as that of an alkane by applying CnH2n+2.
- Describe alkanes as saturated hydrocarbons containing only single covalent bonds.
- Deduce the formula of an alkane from its position in the homologous series.
Crude oil, hydrocarbons and alkanes
The first four members of the alkanes are methane, ethane, propane and butane.
- Name the first four alkanes in order.
- Write the molecular formula of methane, ethane, propane and butane.
- Describe how the formulas of successive alkanes differ by CH₂.
Current, resistance and potential difference
combinations of resistors in series and parallel.
- Apply the series and parallel rules for current and potential difference to resistor combinations.
- Calculate the total resistance of resistors connected in series.
- Explain why adding a resistor in parallel decreases the total resistance of a circuit.
Current, resistance and potential difference
current, I, in amperes, A (amp is acceptable for ampere)
- Define electric current as the rate of flow of charge and state that its unit is the ampere (A).
- Connect an ammeter correctly in series and read current values from a circuit.
- Use I = Q/t and current–potential difference graphs to calculate or interpret current in series and parallel circuits.
Current, resistance and potential difference
Current, potential difference or resistance can be calculated using the equation:
- State and use the equation V = IR to calculate current, potential difference or resistance.
- Rearrange the equation correctly to make current or resistance the subject.
- Apply the equation to numerical problems and give answers with the correct units.
Current, resistance and potential difference
potential difference = current × resistance
- State and use the equation potential difference = current × resistance.
- Rearrange the equation to determine current or resistance from given data.
- Convert between mA and A or kΩ and Ω and apply the equation accurately to a circuit component.
Current, resistance and potential difference
potential difference, V, in volts, V
- Define potential difference as energy transferred per unit charge and state that its unit is the volt (V).
- Connect a voltmeter correctly in parallel and read potential difference values from a circuit.
- Use V = IR and V–I graphs to calculate or interpret potential difference in series and parallel circuits.
Current, resistance and potential difference
Questions will be set using the term potential difference. Students will gain credit for the correct use of either potential difference or voltage.
- Define potential difference as energy transferred per unit charge and state its unit.
- Use the terms potential difference and voltage interchangeably in written and calculated answers.
- Apply V = IR or E = QV to solve numerical problems involving potential difference.
Current, resistance and potential difference
Required practical activity 15: use circuit diagrams to set up and check appropriate circuits to investigate the factors affecting the resistance of electrical circuits. This should include:
- Set up a circuit from a diagram with correct ammeter and voltmeter placement.
- Investigate a factor affecting resistance while controlling other variables.
- Calculate resistance from measurements and evaluate the reliability of the data.
Current, resistance and potential difference
resistance, R, in ohms, Ω
- Define resistance and state its unit, the ohm, Ω.
- Apply R = V ÷ I to calculate resistance, current or potential difference.
- Explain how resistance changes in series, parallel and non-ohmic component contexts.
Current, resistance and potential difference
The current (I) through a component depends on both the resistance (R) of the component and the potential difference (V) across the component. The greater the resistance of the component the smaller the current for a given potential difference (pd) across the component.
- Use the equation V = I × R to calculate current, potential difference or resistance.
- Explain how changing resistance affects current for a fixed potential difference.
- Describe resistance as opposition to current and identify its unit.
Current, resistance and potential difference
the length of a wire at constant temperature
- Describe how the resistance of a metallic wire at constant temperature varies with its length.
- Explain the change in resistance in terms of collisions between charge carriers and lattice ions.
- Use measurements of current and potential difference to calculate resistance for different lengths and interpret the resulting graph.
Current, resistance and potential difference
V = I R
- Recall and apply the equation V = I R.
- Rearrange the equation to calculate current or resistance.
- Use the equation to explain how changing resistance affects current at constant potential difference.
Deforestation
grow crops for biofuels
- State that crops can be grown to produce biofuels.
- Describe how biofuel crops are processed into fuels such as ethanol or biodiesel.
- Explain the advantages and disadvantages of clearing forest to grow biofuel crops.
Deforestation
Large-scale deforestation in tropical areas has occurred to:
- Identify the main reasons for large-scale deforestation in tropical areas as cattle, rice fields and biofuels.
- Explain how each reason meets human demand for food or fuel.
- Relate deforestation to its effects on carbon stores, biodiversity and the environment.
Deforestation
provide land for cattle and rice fields
- State that deforestation can provide land for cattle grazing and rice fields.
- Describe how clearing forest creates pasture for cattle and flooded fields for rice.
- Explain how this land-use change affects carbon dioxide levels, biodiversity and soil.
Density of materials
density = mass / volume
- Use density = mass / volume to calculate density, mass or volume.
- Convert between g/cm³ and kg/m³ correctly.
- Describe a practical method to determine the density of a regular or irregular solid.
Density of materials
density, ρ, in kilograms per metre cubed, kg/m³
- Recall that density is measured in kg/m³ and represented by ρ.
- Convert density values between g/cm³ and kg/m³.
- Apply the correct unit when calculating or comparing densities.
Density of materials
differences in density.
- State the equation for density and use it to calculate density, mass or volume.
- Describe how particle arrangement and spacing explain differences in density between solids, liquids and gases.
- Compare the densities of common materials using typical values and appropriate units.
Density of materials
mass, m, in kilograms, kg
- Identify mass as a quantity measured in kilograms and use the symbol m correctly.
- Convert between grams and kilograms accurately in density calculations.
- Explain the difference between mass in kg and weight in N when describing a material.
Density of materials
Required practical activity 17: use appropriate apparatus to make and record the measurements needed to determine the densities of regular and irregular solid objects and liquids. Volume should be determined from the dimensions of regularly shaped objects, and by a displacement technique for irregularly shaped objects. Dimensions to be measured using appropriate apparatus such as a ruler, micrometer or Vernier callipers.
- Select appropriate apparatus to measure the dimensions and mass of regular and irregular solids and of liquids.
- Use a displacement technique to find the volume of an irregular solid.
- Calculate density from measured mass and volume and evaluate the reliability of the result.
Density of materials
Students should be able to explain the differences in density between the different states of matter in terms of the arrangement of atoms or molecules.
- Describe the particle arrangement in solids, liquids and gases.
- Use the particle model to explain why solids, liquids and gases have different densities.
- Calculate density from mass and volume using ρ = m ÷ V.
Density of materials
Students should be able to recognise/draw simple diagrams to model the difference between solids, liquids and gases.
- Recognise and draw simple particle diagrams for solids, liquids and gases.
- Describe the arrangement and movement of particles in each state of matter.
- Use particle diagrams to explain differences in density between solids, liquids and gases.
Density of materials
The density of a material is defined by the equation:
- Define density as mass per unit volume and identify its units.
- Calculate density from measured mass and volume, including unit conversions.
- Explain floating and sinking by comparing densities of object and fluid.
Density of materials
the different states of matter
- Identify and describe the three states of matter using the particle model.
- Compare the shape, volume and compressibility of solids, liquids and gases.
- Explain changes of state and density differences in terms of particle energy, spacing and motion.
Density of materials
The particle model can be used to explain
- Describe the arrangement and motion of particles in solids, liquids and gases.
- Use the particle model to explain differences in shape, volume and compressibility between the three states.
- Use the particle model and density = mass ÷ volume to explain why gases are less dense than solids and liquids.
Density of materials
volume, V, in metres cubed, m³
- Identify volume as a quantity measured in cubic metres and use the symbol V correctly.
- Calculate the volume of a regular solid and convert cm³ to m³ accurately.
- Describe how to measure the volume of an irregular solid by displacement and record it in m³.
Density of materials
ρ = m / V
- Use ρ = m / V to calculate density, mass or volume.
- Convert between g/cm³ and kg/m³ confidently.
- Apply density calculations to identify materials and explain floating or sinking.
Development of the periodic table
Before the discovery of protons, neutrons and electrons, scientists attempted to classify the elements by arranging them in order of their atomic weights.
- Describe how early scientists attempted to classify elements by arranging them in order of atomic weight.
- Explain the strengths of Mendeleev's periodic table, including leaving gaps and predicting properties of undiscovered elements.
- Explain how the discovery of protons, neutrons and electrons led to the modern periodic table being ordered by atomic number.
Development of the periodic table
Elements with properties predicted by Mendeleev were discovered and filled the gaps. Knowledge of isotopes made it possible to explain why the order based on atomic weights was not always correct.
- Describe how Mendeleev used atomic weight and gaps to arrange the elements.
- Explain how the discovery of predicted elements supported Mendeleev's table.
- Explain why isotopes mean atomic weight is not always the correct basis for ordering elements.
Development of the periodic table
Mendeleev overcame some of the problems by leaving gaps for elements that he thought had not been discovered and in some places changed the order based on atomic weights.
- Explain why Mendeleev left gaps in his periodic table.
- Describe how and why Mendeleev changed the order based on atomic weights.
- Explain how later discoveries supported Mendeleev's predictions.
Development of the periodic table
Students should be able to describe these steps in the development of the periodic table.
- Sequence the main steps in the development of the periodic table.
- Describe how Mendeleev's predictions were tested by later discoveries.
- Explain how isotopes and atomic number led to the modern ordering of the periodic table.
Development of the periodic table
The early periodic tables were incomplete and some elements were placed in inappropriate groups if the strict order of atomic weights was followed.
- Describe why early periodic tables were incomplete.
- Explain how strict atomic weight order could place elements in inappropriate groups.
- Use a specific element pair to illustrate the conflict between mass order and property patterns.
Diamond
In diamond, each carbon atom forms four covalent bonds with other carbon atoms in a giant covalent structure, so diamond is very hard, has a very high melting point and does not conduct electricity.
- Describe the structure of diamond in terms of carbon atoms and covalent bonds.
- Explain why diamond is very hard and has a very high melting point.
- Explain why diamond does not conduct electricity.
Diamond
Students should be able to explain the properties of diamond in terms of its structure and bonding.
- Describe the giant covalent lattice structure of diamond, including that each carbon atom forms four covalent bonds.
- Explain how the number and strength of covalent bonds in diamond account for its very high melting point and hardness.
- Explain why diamond does not conduct electricity in terms of the absence of delocalised electrons.
Diffusion
(in animals, for gaseous exchange) being ventilated.
- Describe how ventilation moves air or water over a gas exchange surface in animals.
- Explain how pressure changes in the thorax cause air to enter and leave the lungs.
- Relate ventilation to the maintenance of concentration gradients for diffusion of oxygen and carbon dioxide.
Diffusion
(in animals) having an efficient blood supply
- Describe how an efficient blood supply helps maintain a concentration gradient.
- Explain how blood flow increases the rate of diffusion at an exchange surface.
- Apply the idea of an efficient blood supply to named examples such as alveoli or villi.
Diffusion
a membrane that is thin, to provide a short diffusion path
- Describe how a thin membrane provides a short diffusion path.
- Explain how a short diffusion path increases the rate of diffusion.
- Apply the idea of a short diffusion path to named exchange surfaces such as alveoli or villi.
Diffusion
A single-celled organism has a relatively large surface area to volume ratio. This allows sufficient transport of molecules into and out of the cell to meet the needs of the organism.
- Describe why a single-celled organism can rely on diffusion alone for transport of molecules into and out of the cell.
- Explain the link between a high surface area to volume ratio and a sufficient rate of diffusion.
- Compare single-celled organisms with larger organisms in terms of surface area to volume ratio and the need for transport systems.
Diffusion
Diffusion is the spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.
- Define diffusion for particles of a gas and for particles of a substance in solution.
- Explain how random particle motion results in net movement from higher to lower concentration.
- Describe how concentration gradient, temperature, surface area and diffusion distance affect the rate of diffusion.
Diffusion
Factors which affect the rate of diffusion are:
- Identify the factors that affect the rate of diffusion.
- Describe how each factor changes the rate of diffusion.
- Apply the factors to explain diffusion in a named biological context.
Diffusion
having a large surface area
- Describe how a large surface area increases the rate of diffusion.
- Give examples of exchange surfaces with folded, branched or flattened shapes.
- Explain how surface area works with concentration gradient and thickness to affect exchange.
Diffusion
In multicellular organisms, surfaces and organ systems are specialised for exchanging materials. This is to allow sufficient molecules to be transported into and out of cells for the organism’s needs. The effectiveness of an exchange surface is increased by:
- Describe why multicellular organisms need specialised surfaces and organ systems for exchange.
- Identify examples of exchange surfaces and the substances they exchange.
- Explain how transport systems link exchange surfaces to cells to meet the organism's needs.
Diffusion
Some of the substances transported in and out of cells by diffusion are oxygen and carbon dioxide in gas exchange, and of the waste product urea from cells into the blood plasma for excretion in the kidney.
- State that oxygen and carbon dioxide move by diffusion during gas exchange.
- Describe the direction of oxygen and carbon dioxide diffusion between alveoli and blood.
- Explain how urea moves from cells into blood plasma and is excreted by the kidney.
Diffusion
Students should be able to calculate and compare surface area to volume ratios.
- Calculate the surface area and volume of simple shapes such as cubes and use them to find a surface area to volume ratio.
- Simplify and present a surface area to volume ratio in the form surface area : volume.
- Compare calculated ratios for different sizes and relate the comparison to the rate of diffusion.
Diffusion
Students should be able to explain how different factors affect the rate of diffusion.
- Describe how concentration gradient, diffusion distance, surface area and temperature affect the rate of diffusion.
- Explain why each factor changes the rate of diffusion in terms of particle movement.
- Apply the factors to explain adaptations of exchange surfaces such as alveoli.
Diffusion
Students should be able to explain how the small intestine and lungs in mammals, gills in fish, and the roots and leaves in plants, are adapted for exchanging materials.
- Describe the exchange surfaces of the small intestine, lungs, fish gills, roots and leaves.
- Explain how each adaptation increases the rate of diffusion.
- Compare adaptations across different organisms using surface area, thickness and concentration gradients.
Diffusion
Students should be able to explain the need for exchange surfaces and a transport system in multicellular organisms in terms of surface area to volume ratio.
- Calculate surface area to volume ratios for simple shapes such as cubes.
- Describe the relationship between organism size and surface area to volume ratio.
- Explain why multicellular organisms need exchange surfaces and a transport system.
Diffusion
Substances may move into and out of cells across the cell membranes via diffusion.
- Describe diffusion as the net movement of particles from higher to lower concentration across a partially permeable membrane.
- Explain how named substances such as oxygen and carbon dioxide move into or out of cells by diffusion.
- Compare diffusion with active transport in terms of energy requirement and direction of movement.
Diffusion
the difference in concentrations (concentration gradient)
- Define concentration gradient in terms of a difference in concentration.
- Explain how the steepness of a gradient affects the rate of diffusion.
- Describe how a gradient is maintained in a named exchange surface.
Diffusion
the surface area of the membrane.
- Describe how the surface area of a membrane affects the rate of diffusion.
- Explain the effect of surface area on diffusion in terms of particles crossing the membrane.
- Apply knowledge of surface area and diffusion to biological examples such as villi and alveoli.
Diffusion
the temperature
- Describe how temperature affects the rate of diffusion.
- Explain the effect of temperature on diffusion in terms of particle kinetic energy and movement.
- Apply knowledge of temperature and diffusion to interpret experimental data or everyday examples.
Direct and alternating potential difference
Mains electricity is an ac supply. In the United Kingdom the domestic electricity supply has a frequency of 50 Hz and is about 230 V.
- State the frequency and approximate potential difference of the UK domestic electricity supply.
- Describe the difference between direct and alternating potential difference in terms of direction of current.
- Relate a frequency of 50 Hz to the number of cycles and direction reversals occurring each second.
Direct and alternating potential difference
Students should be able to explain the difference between direct and alternating potential difference.
- State that direct p.d. keeps a constant polarity while alternating p.d. reverses polarity repeatedly.
- Interpret voltage–time graphs to identify direct and alternating supplies.
- Relate the UK mains frequency of about 50 Hz and quoted 230 V to the alternating p.d. from the mains.
Discovery and development of drugs
Clinical trials use healthy volunteers and patients.
- State that clinical trials use healthy volunteers and patients.
- Describe the different purposes of testing healthy volunteers and patients.
- Explain how placebos and blind trials help produce valid results.
Discovery and development of drugs
If the drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug.
- State that further clinical trials find the optimum dose after safety is established.
- Explain what is meant by the optimum dose of a drug.
- Describe how different doses are compared in clinical trials to identify the optimum dose.
Discovery and development of drugs
In double blind trials, some patients are given a placebo.
- State what a placebo is and why some patients in a double blind trial receive one.
- Explain how a double blind trial reduces bias from both patients and assessing doctors.
- Compare outcomes for patients given the new drug with those given the placebo to judge whether the drug works.
Discovery and development of drugs
Most new drugs are synthesised by chemists in the pharmaceutical industry. However, the starting point may still be a chemical extracted from a plant.
- State that most new drugs are synthesised by chemists in the pharmaceutical industry.
- Describe how a chemical extracted from a plant can be a starting point for a new drug.
- Explain how synthesis and testing allow chemists to develop effective and safe medicines.
Discovery and development of drugs
New drugs are extensively tested for toxicity, efficacy and dose.
- Define toxicity, efficacy and dose in the context of drug testing.
- Describe how each of toxicity, efficacy and dose is investigated during drug development.
- Explain why all three must be assessed before a new drug is approved for use.
Discovery and development of drugs
New medical drugs have to be tested and trialled before being used to check that they are safe and effective.
- State that new medical drugs are tested and trialled before use.
- Describe how testing checks both safety and effectiveness.
- Explain why human trials follow laboratory testing in the development of a new drug.
Discovery and development of drugs
Penicillin was discovered by Alexander Fleming from the Penicillium mould.
- Identify Alexander Fleming as the scientist who discovered penicillin from the Penicillium mould.
- Describe how the mould produced a substance that killed bacteria on a culture plate.
- Explain that penicillin is an antibiotic used against bacterial infections and not viruses.
Discovery and development of drugs
Preclinical testing is done in a laboratory using cells, tissues and live animals.
- State that preclinical testing is carried out in a laboratory using cells, tissues and live animals.
- Describe the order in which cells, tissues and live animals are used.
- Explain why preclinical testing is needed before clinical trials begin.
Discovery and development of drugs
Students should be able to describe the process of discovery and development of potential new medicines, including preclinical and clinical testing.
- Sequence preclinical and clinical testing accurately.
- State the purpose of each testing stage.
- Explain why regulation and licensing are needed before a medicine is used.
Discovery and development of drugs
The heart drug digitalis originates from foxgloves.
- Identify foxgloves as the natural source of the heart drug digitalis.
- Describe the effect of digitalis on heart muscle contraction.
- Explain that the active compound is extracted and developed into a safe medicine.
Discovery and development of drugs
The painkiller aspirin originates from willow.
- Identify willow as the natural source linked to the painkiller aspirin.
- Describe how salicin from willow led to the development of aspirin.
- Explain that aspirin is a purified or modified active compound rather than raw willow bark.
Discovery and development of drugs
Traditionally drugs were extracted from plants and microorganisms.
- Identify plants and microorganisms as traditional sources of drugs.
- Give named examples of drugs from natural sources.
- Describe how a natural source led to a useful medicine.
Discovery and development of drugs
Very low doses of the drug are given at the start of the clinical trial.
- State that very low doses are given at the start of a clinical trial.
- Explain why starting with a very low dose improves safety for volunteers.
- Describe how the dose is increased gradually during a clinical trial.
Distance and displacement
Displacement includes both the distance an object moves, measured in a straight line from the start point to the finish point and the direction of that straight line. Displacement is a vector quantity.
- State that displacement is the straight-line distance from start point to finish point together with its direction.
- Identify displacement as a vector quantity and distance as a scalar quantity.
- Calculate or measure the magnitude and direction of a displacement for a simple two-part journey.
Distance and displacement
Distance is how far an object moves. Distance does not involve direction. Distance is a scalar quantity.
- State that distance is the total path length travelled and is a scalar quantity.
- Compare distance with displacement using a simple journey example.
- Quote distance values with correct units and no direction.
Distance and displacement
Students should be able to express a displacement in terms of both the magnitude and direction.
- Write a displacement as a magnitude with a unit together with a direction.
- Measure the magnitude and direction of a displacement from a scale diagram.
- Convert a measured angle into a three-figure bearing when required.
DNA and the genome
A gene is a small section of DNA on a chromosome. Each gene codes for a particular sequence of amino acids, to make a specific protein.
- Define a gene as a small section of DNA on a chromosome.
- Explain that a gene codes for a particular sequence of amino acids.
- Relate the amino acid sequence coded by a gene to the specific protein made.
DNA and the genome
search for genes linked to different types of disease
- Describe how genomes are compared to find gene variants linked to disease.
- Explain why a statistical link between a gene variant and a disease is not proof of causation.
- Apply the idea to a named disease and state a medical benefit of the finding.
DNA and the genome
Students should be able to describe the structure of DNA and define genome.
- Describe DNA as a polymer made of two strands forming a double helix.
- State that DNA is contained in structures called chromosomes.
- Define genome as the entire genetic material of an organism.
DNA and the genome
Students should be able to discuss the importance of understanding the human genome.
- Describe medical benefits of understanding the human genome.
- Identify limitations and ethical concerns of using human genome information.
- Reach a supported judgement about the importance of understanding the human genome.
DNA and the genome
The genetic material in the nucleus of a cell is composed of a chemical called DNA. DNA is a polymer made up of two strands forming a double helix. The DNA is contained in structures called chromosomes.
- State that DNA is the chemical making up the genetic material in the nucleus.
- Describe DNA as a polymer of two strands forming a double helix.
- Identify chromosomes as the structures that contain DNA in the nucleus.
DNA and the genome
The genome of an organism is the entire genetic material of that organism. The whole human genome has now been studied and this will have great importance for medicine in the future.
- Define the genome as the entire genetic material of an organism.
- Describe that the whole human genome has been studied and sequenced.
- Explain how understanding the human genome can be important for medicine in the future.
DNA and the genome
understanding and treatment of inherited disorders
- Describe how recessive and dominant alleles cause inherited disorders.
- Use genetic diagrams to predict the probability of offspring inheriting a disorder.
- Explain how knowledge of inheritance supports counselling, screening and treatment of inherited disorders.
DNA and the genome
use in tracing human migration patterns from the past.
- Describe how DNA sequences can be compared to trace human migration.
- Explain why mitochondrial DNA and the Y chromosome are useful for tracing ancestry.
- Interpret data on DNA similarities to identify relatedness between populations.
Efficiency
(HT only) Students should be able to describe ways to increase the efficiency of an intended energy transfer.
- Identify the useful and wasted energy transfers for a given device.
- Describe at least two practical methods that reduce unwanted energy transfers.
- Explain how reducing wasted transfers increases the efficiency of the intended energy transfer.
Efficiency
efficiency = useful output energy transfer / total input energy transfer
- Apply the efficiency equation to numerical data from a device or process.
- Convert between decimal and percentage forms of efficiency.
- Explain how efficiency relates to wasted energy and the cost of running a device.
Efficiency
efficiency = useful power output / total power input
- Apply efficiency = useful power output / total power input to numerical data and obtain a correct value.
- Convert between decimal and percentage forms of efficiency and interpret the result.
- Explain why efficiency has no unit and why it is always less than 1 for a real device.
Efficiency
Efficiency may also be calculated using the equation:
- Select the useful power output and total power input from given data and substitute them into the efficiency equation.
- Calculate efficiency as a decimal or percentage and interpret what the value means for a device.
- Explain why efficiency can be found using either energy or power values and identify where wasted power goes.
Efficiency
The energy efficiency for any energy transfer can be calculated using the equation:
- Select the correct useful output and total input energies for a described transfer.
- Apply the efficiency equation accurately to obtain a decimal or percentage.
- Interpret an efficiency value to compare devices and identify energy losses.
Electric motors (HT only)
A coil of wire carrying a current in a magnetic field tends to rotate. This is the basis of an electric motor.
- Describe how forces on a current-carrying coil in a magnetic field produce rotation.
- Explain the function of the split-ring commutator in an electric motor.
- Relate changes in current, number of turns and magnetic flux density to the turning effect on the coil.
Electric motors (HT only)
Students should be able to explain how the force on a conductor in a magnetic field causes the rotation of the coil in an electric motor.
- Describe the force on a current-carrying conductor in a magnetic field and state its direction using Fleming's left-hand rule.
- Explain how opposite forces on the two sides of a coil produce rotation about its axis.
- Explain the role of the split-ring commutator in maintaining continuous rotation in the same direction.
Electrical charge and current
A current has the same value at any point in a single closed loop.
- Describe current as the rate of flow of charge in a circuit.
- Explain why the current is the same at all points in a single closed loop using conservation of charge.
- Predict and compare ammeter readings at different positions in a series circuit.
Electrical charge and current
charge flow = current × time
- Recall and write the equation charge flow = current × time.
- Use the equation to calculate charge flow, current or time from given values.
- Convert time to seconds and give answers with correct units.
Electrical charge and current
charge flow, Q, in coulombs, C
- Define charge flow and state its unit, the coulomb.
- Calculate charge flow using Q = I t with correct units.
- Explain that charge is conserved in circuits and relate charge to the number of electrons.
Electrical charge and current
current, I, in amperes, A (amp is acceptable for ampere)
- Define electric current as the rate of flow of charge and give its unit, the ampere (A).
- Select and use the symbol I and the unit A correctly in written and calculated answers.
- Connect an ammeter in series and interpret its reading as the current through a component.
Electrical charge and current
Electric current is a flow of electrical charge. The size of the electric current is the rate of flow of electrical charge. Charge flow, current and time are linked by the equation:
- Describe electric current as a flow of electrical charge and explain that current is the rate of flow of charge.
- Use the equation charge flow = current × time to calculate charge flow, current or time.
- Apply correct units for charge flow, current and time in calculations and answers.
Electrical charge and current
For electrical charge to flow through a closed circuit the circuit must include a source of potential difference.
- Explain why both a closed circuit and a source of potential difference are needed for charge to flow.
- Describe current as the rate of flow of charge and use Q = It to calculate charge, current or time.
- Predict the effect on current of opening a switch or removing the source of potential difference from a circuit.
Electrical charge and current
Q = I t
- State and apply the equation Q = I t to calculate charge flow, current or time.
- Convert time values into seconds and use consistent SI units in calculations.
- Explain the meaning of one coulomb in terms of one ampere flowing for one second.
Electrical charge and current
time, t, in seconds, s
- State that time is measured in seconds (s) and identify t as its symbol.
- Convert times given in minutes, hours or milliseconds into seconds before substitution.
- Rearrange and use Q = I t to determine a time from measured charge and current.
Electrolysis of aqueous solutions
At the negative electrode (cathode), hydrogen is produced if the metal is more reactive than hydrogen.
- Identify the cathode as the negative electrode and describe reduction of positive ions there.
- Use the reactivity series to predict whether hydrogen or a metal forms at the cathode.
- Write a balanced cathode half-equation for the discharge of H⁺ or a metal ion.
Electrolysis of aqueous solutions
At the positive electrode (anode), oxygen is produced unless the solution contains halide ions when the halogen is produced.
- Identify the anode as the positive electrode and describe oxidation of negative ions there.
- Decide whether oxygen or a halogen forms by checking for halide ions in the solution.
- Write a balanced anode half-equation and suggest a test for the product.
Electrolysis of aqueous solutions
Required practical activity 9: investigate what happens when aqueous solutions are electrolysed using inert electrodes. This should be an investigation involving developing a hypothesis.
- Plan an investigation to electrolyse aqueous solutions using inert electrodes and formulate a testable hypothesis.
- Carry out the electrolysis safely and record observations at the cathode and anode accurately.
- Explain the products formed at each electrode using ion discharge rules and the reactivity series, and evaluate the hypothesis against evidence.
Electrolysis of aqueous solutions
Students should be able to predict the products of the electrolysis of aqueous solutions containing a single ionic compound.
- List all ions present in an aqueous solution of a single ionic compound.
- Apply the rules for discharge at the cathode and anode to name the products.
- Justify predictions using reactivity, ease of discharge and half-equations.
Electrolysis of aqueous solutions
The ions discharged when an aqueous solution is electrolysed using inert electrodes depend on the relative reactivity of the elements involved.
- List the ions present in an aqueous solution, including H⁺ and OH⁻ from water.
- Use relative reactivity to predict which ions are discharged at the cathode and anode.
- Write half-equations for the discharge of chosen ions and name the products formed.
Electrolysis of aqueous solutions
This happens because in the aqueous solution water molecules break down producing hydrogen ions and hydroxide ions that are discharged.
- State that water molecules ionise to produce H⁺ and OH⁻ in aqueous solution.
- Predict the products of electrolysis of aqueous solutions based on reactivity and the presence of halide ions.
- Explain how sodium hydroxide is formed during the electrolysis of aqueous sodium chloride.
Electrolysis of molten ionic compounds
Students should be able to predict the products of the electrolysis of binary ionic compounds in the molten state.
- Deduce the ions present in a binary ionic compound from its formula.
- Predict the element formed at each electrode when a named molten binary ionic compound is electrolysed.
- (HT only) Explain the formation of elements at electrodes in terms of electron transfer.
Electrolysis of molten ionic compounds
When a simple ionic compound (eg lead bromide) is electrolysed in the molten state using inert electrodes, the metal (lead) is produced at the cathode and the non-metal (bromine) is produced at the anode.
- Describe the products formed at the cathode and anode when a molten ionic compound is electrolysed.
- Explain why a simple ionic compound must be molten to undergo electrolysis.
- (HT only) Write balanced ionic half-equations for the oxidation and reduction reactions at the electrodes.
Electromagnetism
describe how the magnetic effect of a current can be demonstrated
- Describe a practical method using iron filings or a plotting compass to show the magnetic field around a current-carrying wire.
- Explain how the pattern changes when the current is increased or reversed.
- State that the magnetic effect disappears when the current is switched off.
Electromagnetism
draw the magnetic field pattern for a straight wire carrying a current and for a solenoid (showing the direction of the field)
- Draw the magnetic field pattern around a straight current-carrying wire, including direction arrows.
- Draw the magnetic field pattern of a solenoid, showing the direction of the field inside and outside.
- Apply the right-hand grip rule to determine the direction of the magnetic field.
Electromagnetism
explain how a solenoid arrangement can increase the magnetic effect of the current.
- Describe how winding a current-carrying wire into a solenoid increases the magnetic effect.
- Explain how current, number of turns per unit length and a soft iron core affect the strength of a solenoid's magnetic field.
- Compare the magnetic field pattern of a solenoid with that of a bar magnet.
Electromagnetism
Shaping a wire to form a solenoid increases the strength of the magnetic field created by a current through the wire. The magnetic field inside a solenoid is strong and uniform.
- Describe how shaping a wire into a solenoid affects the magnetic field produced by a current.
- Explain why the magnetic field inside a solenoid is strong and uniform.
- Identify ways to increase the strength of the magnetic field of a solenoid.
Electromagnetism
The magnetic field around a solenoid has a similar shape to that of a bar magnet. Adding an iron core increases the strength of the magnetic field of a solenoid. An electromagnet is a solenoid with an iron core.
- Describe the shape of the magnetic field around a current-carrying solenoid and compare it with a bar magnet's field.
- Explain how adding a soft iron core changes the strength of a solenoid's magnetic field.
- Define an electromagnet and state one advantage it has over a permanent magnet.
Electromagnetism
When a current flows through a conducting wire a magnetic field is produced around the wire. The strength of the magnetic field depends on the current through the wire and the distance from the wire.
- Describe how a current-carrying wire produces a magnetic field around it.
- Explain how the strength of the magnetic field depends on current and distance from the wire.
- Apply the right-hand grip rule to determine the direction of the magnetic field around a straight wire.
Electronic structure
showing two electrons in the lowest energy level, eight in the second energy level and one in the third energy level.
- Draw a labelled energy-level diagram for an atom with up to 20 electrons.
- State the electron arrangement of an element from its atomic number.
- Relate the number of outer-shell electrons to the element's group.
Electronic structure
The electrons in an atom occupy the lowest available energy levels (innermost available shells). The electronic structure of an atom can be represented by numbers or by a diagram. For example, the electronic structure of sodium is 2,8,1 or
- Write the electronic structure of an atom using numbers or a shell diagram.
- Explain why electrons fill the lowest available energy levels first.
- Deduce an element's group and likely ion charge from its outer-shell electron count.
Energy changes and reversible reactions
If a reversible reaction is exothermic in one direction, it is endothermic in the opposite direction. The same amount of energy is transferred in each case. For example:
- State that in a reversible reaction, if one direction is exothermic, the opposite direction is endothermic.
- Describe that the same amount of energy is transferred in each direction of a reversible reaction.
- Apply the principle to a given example by identifying which direction is exothermic and which is endothermic.
Energy changes in systems
∆E = m c ∆θ
- Recall and use the equation ΔE = m c Δθ with correct symbols and units.
- Rearrange the equation to determine mass, specific heat capacity or temperature change.
- Apply the equation to real heating and cooling contexts and interpret the sign of the energy change.
Energy changes in systems
change in thermal energy = mass × specific heat capacity × temperature change
- Select and apply the equation change in thermal energy = mass × specific heat capacity × temperature change to calculate energy transferred.
- Convert between grams and kilograms and calculate temperature change correctly before substitution.
- Explain the meaning of specific heat capacity and use it to compare how different materials respond to heating.
Energy changes in systems
change in thermal energy, ∆E, in joules, J
- State that change in thermal energy ∆E is measured in joules, J.
- Apply the equation ∆E = mc∆θ to calculate energy changes for a given mass and temperature change.
- Interpret the sign of ∆E to describe whether a system gains or loses thermal energy.
Energy changes in systems
mass, m, in kilograms, kg
- State that mass m is measured in kilograms, kg, in thermal energy calculations.
- Convert masses between grams and kilograms accurately before using the equation ∆E = mc∆θ.
- Use mass correctly in calculations and distinguish it from weight in newtons.
Energy changes in systems
Required practical activity 14: an investigation to determine the specific heat capacity of one or more materials. The investigation will involve linking the decrease of one energy store (or work done) to the increase in temperature and subsequent increase in thermal energy stored.
- Carry out an investigation to determine the specific heat capacity of a material.
- Link a decrease in one energy store or work done to an increase in thermal energy stored.
- Evaluate sources of error and suggest improvements to the method.
Energy changes in systems
specific heat capacity, c, in joules per kilogram per degree Celsius, J/kg °C
- Define specific heat capacity and state its unit as J/kg °C.
- Calculate energy change, mass, temperature change or specific heat capacity using E = mc∆θ.
- Explain how the magnitude of c affects the temperature change of a substance for a given energy transfer.
Energy changes in systems
temperature change, ∆θ, in degrees Celsius, °C
- Calculate temperature change from initial and final temperatures using ∆θ = θ_final − θ_initial.
- Use ∆θ correctly in the equation E = mc∆θ, including the sign for a temperature fall.
- Explain that a temperature change of 1 °C is equal in size to a temperature change of 1 K.
Energy changes in systems
The amount of energy stored in or released from a system as its temperature changes can be calculated using the equation:
- Use the equation ΔE = m c Δθ to calculate energy changes for a named substance.
- Determine the temperature change of a system from initial and final temperature values.
- Explain how mass, specific heat capacity and temperature change each affect the energy transferred.
Energy changes in systems
The specific heat capacity of a substance is the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius.
- Define specific heat capacity in terms of energy, mass and temperature change.
- Apply ΔE = mcΔθ to calculate energy transferred, mass, specific heat capacity or temperature change.
- Compare the thermal behaviour of different materials using their specific heat capacity values.
Energy stores and systems
a moving object hitting an obstacle
- Describe the energy transfers when a moving object hits an obstacle, naming stores and pathways.
- Explain how conservation of energy applies to the impact, including thermal and sound transfers.
- Calculate kinetic energy using Ek = ½mv² and relate it to energy transferred on impact.
Energy stores and systems
A system is an object or group of objects.
- Define a system as an object or a group of objects.
- Identify the boundary between a chosen system and its surroundings.
- Apply the idea of a system to a simple physical situation.
Energy stores and systems
a vehicle slowing down
- Identify the kinetic energy store of a moving vehicle and explain how it changes when the vehicle slows down.
- Describe the energy transfer pathways from the vehicle's kinetic energy store to thermal energy stores of brakes and surroundings.
- Apply the conservation of energy to account for the decrease in kinetic energy when a vehicle slows down.
Energy stores and systems
an object accelerated by a constant force
- Describe how a constant force transfers energy to an object's kinetic energy store.
- Calculate work done using W = Fs and relate it to energy transfers.
- Explain how a constant resultant force produces constant acceleration and how friction affects the energy transfer.
Energy stores and systems
an object projected upwards
- Describe how kinetic and gravitational potential stores change as an object moves upwards and downwards.
- Identify the highest point as the position where kinetic store is zero and gravitational potential store is maximum.
- Explain the effect of air resistance on the energy transferred during the motion.
Energy stores and systems
bringing water to a boil in an electric kettle.
- Describe the energy transfers that occur when an electric kettle brings water to a boil.
- Explain why the temperature of water remains constant during boiling despite continued energy transfer.
- Evaluate the efficiency of an electric kettle by considering energy transferred to the surroundings.
Energy stores and systems
heating
- Describe how heating transfers energy from a hotter region to a cooler region.
- Calculate the energy transferred using ΔE = m × c × Δθ or E = m × L as appropriate.
- Interpret a temperature-time graph to identify changes of state and temperature changes.
Energy stores and systems
Students should be able to describe all the changes involved in the way energy is stored when a system changes, for common situations. For example:
- Identify the energy stores that change when a named system changes.
- State the pathway by which energy is transferred between stores.
- Describe complete energy changes for common situations using conservation of energy.
Energy stores and systems
There are changes in the way energy is stored when a system changes.
- Describe how energy stores change when a system changes.
- Identify the pathway by which energy is transferred between stores.
- Apply conservation of energy to closed systems where total energy remains constant.
Energy stores and systems
Throughout this section on Energy students should be able to calculate the changes in energy involved when a system is changed by:
- Identify the energy stores that change when a described system is altered.
- Select and apply the correct equation to calculate an energy change in joules.
- Explain, using conservation of energy, why the total energy before and after a change is the same.
Energy stores and systems
use calculations to show on a common scale how the overall energy in a system is redistributed when the system is changed.
- Identify the energy stores present before and after a described change in a system.
- Calculate the energy in each relevant store using the appropriate equation and correct units.
- Present before-and-after energy values on a common scale and use them to explain how energy has been redistributed.
Energy stores and systems
work done by forces
- State the condition needed for a force to do work on an object.
- Apply W = F s to calculate work done, force or distance, including rearrangement.
- Explain why a force at right angles to motion does no work and relate work done to energy transferred.
Energy stores and systems
work done when a current flows
- State that work is done when charge flows in a circuit.
- Apply E = Q × V to calculate work done, charge flow or potential difference.
- Distinguish between electrical work and heating as distinct energy transfer pathways.
Energy transfer during exothermic and endothermic reactions
An endothermic reaction is one that takes in energy from the surroundings so the temperature of the surroundings decreases.
- Define an endothermic reaction in terms of energy transfer from the surroundings.
- Relate a decrease in the temperature of the surroundings to energy being taken in.
- Represent an endothermic change on an energy level diagram with products higher than reactants.
Energy transfer during exothermic and endothermic reactions
An exothermic reaction is one that transfers energy to the surroundings so the temperature of the surroundings increases.
- Define an exothermic reaction as one that transfers energy to the surroundings, causing a temperature increase.
- Describe how to identify an exothermic reaction from a temperature change in the surroundings.
- Give examples of exothermic reactions and explain the energy transfer involved.
Energy transfer during exothermic and endothermic reactions
distinguish between exothermic and endothermic reactions on the basis of the temperature change of the surroundings
- Define exothermic and endothermic reactions in terms of energy transfer to or from the surroundings.
- Interpret temperature change data to classify a reaction correctly.
- Explain a classification using the direction of energy transfer rather than temperature alone.
Energy transfer during exothermic and endothermic reactions
Endothermic reactions include thermal decompositions and the reaction of citric acid and sodium hydrogencarbonate. Some sports injury packs are based on endothermic reactions.
- Identify thermal decomposition and the citric acid–sodium hydrogencarbonate reaction as endothermic.
- Explain how an endothermic reaction can be used in a sports injury pack to cool the body.
- Describe the temperature change of the surroundings as evidence for an endothermic reaction.
Energy transfer during exothermic and endothermic reactions
Energy is conserved in chemical reactions. The amount of energy in the universe at the end of a chemical reaction is the same as before the reaction takes place. If a reaction transfers energy to the surroundings the product molecules must have less energy than the reactants, by the amount transferred.
- State that energy is conserved in chemical reactions and that the total energy of the universe remains constant.
- Explain, using the idea of energy conservation, why products have less energy than reactants when energy is transferred to the surroundings.
- Interpret simple energy level diagrams to identify whether a reaction is exothermic or endothermic and the energy transferred.
Energy transfer during exothermic and endothermic reactions
evaluate uses and applications of exothermic and endothermic reactions given appropriate information.
- Classify given reactions as exothermic or endothermic using temperature or energy-transfer information.
- Explain how the direction of energy transfer produces a warming or cooling effect in a named application.
- Evaluate the suitability of a reaction for a stated use by weighing benefits against limitations and reaching a justified conclusion.
Energy transfer during exothermic and endothermic reactions
Everyday uses of exothermic reactions include self-heating cans and hand warmers.
- Describe how self-heating cans and hand warmers use exothermic reactions.
- Explain that energy is transferred to the surroundings in these devices, causing a temperature rise.
- Evaluate the suitability of an exothermic reaction for an everyday heating device using given information.
Energy transfer during exothermic and endothermic reactions
Exothermic reactions include combustion, many oxidation reactions and neutralisation.
- Identify combustion, many oxidation reactions and neutralisation as exothermic reactions.
- Describe the energy transfer to the surroundings in an exothermic reaction using a temperature rise.
- Interpret experimental temperature data to classify a reaction as exothermic.
Energy transfer during exothermic and endothermic reactions
Required practical activity 10: investigate the variables that affect temperature changes in reacting solutions such as, eg acid plus metals, acid plus carbonates, neutralisations, displacement of metals.
- Plan a safe procedure to measure temperature change in a reacting solution.
- Record and process temperature data to calculate ΔT.
- Interpret results to classify reactions as exothermic or endothermic and identify variables that affect ΔT.
Energy transfers in a system
Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed.
- State the principle of conservation of energy.
- Describe energy transfers between stores and identify useful and dissipated energy.
- Apply conservation of energy to account for energy in a simple system.
Energy transfers in a system
Students should be able to describe how the rate of cooling of a building is affected by the thickness and thermal conductivity of its walls.
- Describe how the rate of cooling of a building depends on the thermal conductivity of its walls.
- Describe how the rate of cooling of a building depends on the thickness of its walls.
- Compare the cooling rates of buildings with walls of different thickness and thermal conductivity.
Energy transfers in a system
Students should be able to describe with examples where there are energy transfers in a closed system, that there is no net change to the total energy.
- Define a closed system and state that the total energy within it remains constant.
- Describe energy transfers between named stores in a given closed system.
- Apply the principle of conservation of energy to show no net change in total energy.
Energy transfers in a system
Students should be able to describe, with examples, how in all system changes energy is dissipated, so that it is stored in less useful ways. This energy is often described as being ‘wasted’.
- Describe how energy is dissipated in system changes, using specific examples.
- Explain why dissipated energy is stored in less useful ways and is often called wasted.
- Identify the useful and dissipated energy transfers in a given system change.
Energy transfers in a system
Students should be able to explain ways of reducing unwanted energy transfers, for example through lubrication and the use of thermal insulation.
- Describe how lubrication reduces unwanted energy transfer by friction.
- Explain how thermal insulation reduces conduction, convection and radiation.
- Apply these ideas to a named everyday context and compare rates of cooling.
Energy transfers in a system
The higher the thermal conductivity of a material the higher the rate of energy transfer by conduction across the material.
- State that thermal conductivity describes how well a material conducts energy.
- Explain why a higher thermal conductivity gives a higher rate of conduction.
- Compare two materials fairly by controlling thickness, area and temperature difference.
Energy transfers in everyday appliances
charge flow, Q, in coulombs, C
- State that charge flow is measured in coulombs and use the symbol Q.
- Calculate charge flow using Q = I × t with time in seconds.
- Apply Q in energy transfer calculations using E = Q × V.
Energy transfers in everyday appliances
E = P t
- Recall and use the equation E = P t with correct units for each symbol.
- Rearrange E = P t to find power or time when the other two quantities are known.
- Apply the equation to everyday appliances and interpret the result in context.
Energy transfers in everyday appliances
E = Q V
- Recall and use the equation E = Q V.
- Rearrange E = Q V to calculate charge flow or potential difference.
- Apply the equation to energy transfers in everyday appliances.
Energy transfers in everyday appliances
energy transferred = charge flow × potential difference
- Recall and apply the equation energy transferred = charge flow × potential difference.
- Calculate energy transferred, charge flow or potential difference when two quantities are known.
- Explain how the equation relates to energy transfers in everyday electrical appliances.
Energy transfers in everyday appliances
energy transferred = power × time
- State the relationship energy transferred = power × time and identify the unit of each quantity.
- Convert time into seconds and power into watts before substituting into the equation.
- Calculate the energy transferred by an everyday appliance and express the answer in joules or kilojoules.
Energy transfers in everyday appliances
energy transferred, E, in joules, J
- State the equation E = P × t and identify the unit of energy transferred as the joule, J.
- Calculate energy transferred in joules for an appliance when power in watts and time in seconds are given.
- Describe useful and wasted energy transfers in a named everyday appliance using the idea of energy conservation.
Energy transfers in everyday appliances
Everyday electrical appliances are designed to bring about energy transfers.
- Describe the useful and unwanted energy transfers in everyday electrical appliances.
- Use the equation E = P × t to calculate energy transferred by an appliance.
- Explain how appliance design can increase the proportion of useful energy transferred.
Energy transfers in everyday appliances
potential difference, V, in volts, V
- Define potential difference as energy transferred per unit charge and state its unit.
- Select and use the correct equation linking potential difference, energy transferred and charge.
- Draw or interpret a circuit diagram showing a voltmeter connected in parallel to measure potential difference.
Energy transfers in everyday appliances
power, P, in watts, W
- Define power as the rate of energy transfer and state its unit as the watt, W.
- Calculate power in watts using P = E ÷ t when energy in joules and time in seconds are known.
- Compare the power ratings of everyday appliances and explain how power affects the rate of energy transfer.
Energy transfers in everyday appliances
Students should be able to describe how different domestic appliances transfer energy from batteries or ac mains to the kinetic energy of electric motors or the energy of heating devices.
- Describe the energy transfers in a range of domestic appliances powered by batteries or the ac mains.
- Distinguish between appliances that produce kinetic energy and those designed for heating.
- Identify useful and unwanted energy transfers in everyday examples.
Energy transfers in everyday appliances
Students should be able to describe, with examples, the relationship between the power ratings for domestic electrical appliances and the changes in stored energy when they are in use.
- State the relationship between power rating, time and energy transferred for a domestic appliance.
- Calculate the energy transferred by an appliance using E = P × t with correct unit conversions.
- Explain, using examples, how changing the power rating or the time of use changes the energy in stores.
Energy transfers in everyday appliances
Students should be able to explain how the power of a circuit device is related to:
- Explain how power depends on both potential difference and current for a circuit device.
- Use P = VI to calculate power, potential difference or current when the other two quantities are known.
- Apply P = VI and E = Pt to compare the energy transfers of everyday appliances.
Energy transfers in everyday appliances
The amount of energy an appliance transfers depends on how long the appliance is switched on for and the power of the appliance.
- Use the equation E = P × t to calculate energy transferred by an appliance.
- Explain how changing power or operating time affects the energy transferred.
- Compare the energy transferred by different appliances using calculated values.
Energy transfers in everyday appliances
The amount of energy transferred by electrical work can be calculated using the equation:
- Use E = QV to calculate energy transferred by electrical work.
- Combine Q = It with E = QV to solve problems involving current, time and potential difference.
- Rearrange the equation to determine charge or potential difference from energy transferred.
Energy transfers in everyday appliances
the energy transferred over a given time.
- Use the equation E = P × t to calculate energy transferred, power or time.
- Convert between watts and kilowatts and between minutes and seconds as required.
- Apply energy transfer calculations to realistic everyday appliance contexts.
Energy transfers in everyday appliances
the potential difference across it and the current through it
- Identify potential difference and current as the two quantities that determine the energy transferred by an appliance.
- Describe how to measure potential difference and current correctly in a circuit.
- Explain how changing potential difference or current affects the rate of energy transfer in an everyday appliance.
Energy transfers in everyday appliances
time, t, in seconds, s
- State that time is measured in seconds and use the symbol t correctly.
- Calculate charge flow or energy transfer using time in seconds.
- Convert times given in minutes or hours into seconds before substitution.
Energy transfers in everyday appliances
Work is done when charge flows in a circuit.
- Describe how work is done when charge flows through a circuit component.
- Apply E = QV to calculate energy transferred, charge or potential difference.
- Explain how changing charge flow or potential difference affects the energy transferred in an everyday appliance.
Equilibrium
When a reversible reaction occurs in apparatus which prevents the escape of reactants and products, equilibrium is reached when the forward and reverse reactions occur at exactly the same rate.
- State the conditions required for equilibrium in a reversible reaction.
- Describe what happens to the rates of the forward and reverse reactions at equilibrium.
- Explain why the concentrations of reactants and products remain constant at equilibrium.
Eukaryotes and prokaryotes
Bacterial cells (prokaryotic cells) are much smaller in comparison. They have cytoplasm and a cell membrane surrounded by a cell wall. The genetic material is not enclosed in a nucleus. It is a single DNA loop and there may be one or more small rings of DNA called plasmids.
- Label a bacterial cell diagram with cytoplasm, cell membrane, cell wall, single DNA loop and plasmids.
- Compare a named prokaryotic cell with a named eukaryotic cell, stating at least two structural differences.
- Explain the function of the cell wall, cell membrane, DNA loop and plasmids in a bacterial cell.
Eukaryotes and prokaryotes
Plant and animal cells (eukaryotic cells) have a cell membrane, cytoplasm and genetic material enclosed in a nucleus.
- State the three features shared by all plant and animal cells as eukaryotic cells.
- Describe the function of the cell membrane, cytoplasm and nucleus in a eukaryotic cell.
- Compare eukaryotic cells with prokaryotic cells, noting that prokaryotes have no nucleus.
Eukaryotes and prokaryotes
Students should be able to demonstrate an understanding of the scale and size of cells and be able to make order of magnitude calculations, including the use of standard form.
- Convert cell measurements between micrometres and metres and write them in standard form.
- Calculate the order of magnitude difference between two cell sizes by comparing powers of ten.
- Explain why a common unit such as the micrometre is needed when comparing the sizes of different cells.
Evidence for evolution
Evidence for Darwin’s theory is now available as it has been shown that characteristics are passed on to offspring in genes. There is further evidence in the fossil record and the knowledge of how resistance to antibiotics evolves in bacteria.
- Explain how genes provide evidence for Darwin’s theory.
- Describe how the fossil record and antibiotic resistance support evolution.
- Apply the idea of natural selection to explain the spread of antibiotic resistance.
Evidence for evolution
Students should be able to describe the evidence for evolution including fossils and antibiotic resistance in bacteria.
- Describe how fossils provide evidence that organisms have changed over time.
- Explain how antibiotic resistance in bacteria demonstrates natural selection.
- Compare the timescales and types of evidence provided by fossils and by antibiotic resistance.
Evidence for evolution
The theory of evolution by natural selection is now widely accepted.
- Describe how natural selection leads to evolution over generations.
- Explain why the theory of evolution by natural selection is widely accepted.
- Use a named example to illustrate natural selection.
Evolution
If two populations of one species become so different in phenotype that they can no longer interbreed to produce fertile offspring they have formed two new species.
- Describe how reproductive isolation can lead to the formation of two new species.
- Explain how different selection pressures and mutation cause populations to diverge in phenotype.
- State that two populations are separate species when they can no longer interbreed to produce fertile offspring.
Evolution
Students should be able to describe evolution as a change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species.
- Define evolution as a change in the inherited characteristics of a population over time.
- Describe the process of natural selection leading to changes in allele frequency.
- Explain how natural selection may result in the formation of a new species when populations become reproductively isolated.
Evolution
Students should be able to explain how evolution occurs through natural selection of variants that give rise to phenotypes best suited to their environment.
- Explain how natural selection acts on variants that produce phenotypes suited to the environment.
- Describe how advantageous alleles increase in frequency over generations.
- Apply the mechanism of natural selection to unfamiliar examples, such as antibiotic resistance.
Evolution
The theory of evolution by natural selection states that all species of living things have evolved from simple life forms that first developed more than three billion years ago.
- State that all species have evolved from simple life forms that developed more than three billion years ago.
- Describe evolution as a change in inherited characteristics of populations over generations.
- Use fossil and molecular evidence to support the theory of evolution by natural selection.
Extinction
Extinctions occur when there are no remaining individuals of a species still alive.
- Define extinction as the situation where no individuals of a species remain alive.
- Distinguish extinction from endangerment and local disappearance.
- Apply the definition to a simple example of a species dying out.
Extinction
Students should be able to describe factors which may contribute to the extinction of a species.
- Identify a range of factors that can contribute to extinction.
- Describe how each factor reduces the survival or reproduction of a species.
- Explain how combined factors can lead to no remaining individuals of a species.
Extraction of metals and reduction
identify the substances which are oxidised or reduced in terms of gain or loss of oxygen.
- Define oxidation and reduction in terms of gain or loss of oxygen.
- Track oxygen atoms in a chemical equation to determine which substances are oxidised or reduced.
- Apply the oxygen-based definitions to metal extraction reactions.
Extraction of metals and reduction
interpret or evaluate specific metal extraction processes when given appropriate information
- Interpret supplied data or diagrams to explain how a specific metal is extracted from its ore.
- Evaluate a named extraction process by comparing evidence such as energy use, cost or environmental impact.
- Justify a conclusion about an extraction process using both the reactivity series and the information provided.
Extraction of metals and reduction
Metals less reactive than carbon can be extracted from their oxides by reduction with carbon.
- Use the reactivity series to decide whether a metal can be extracted by reduction with carbon.
- Describe reduction as the removal of oxygen from a metal oxide by carbon.
- Write balanced equations for the extraction of a named metal from its oxide using carbon.
Extraction of metals and reduction
Reduction involves the loss of oxygen.
- State that reduction involves the loss of oxygen.
- Identify which substance is reduced in a given chemical equation.
- Explain how reduction and oxidation occur together in a redox reaction such as metal extraction.
Extraction of metals and reduction
Unreactive metals such as gold are found in the Earth as the metal itself but most metals are found as compounds that require chemical reactions to extract the metal.
- Distinguish native metals from metals found as compounds in ores.
- Describe reduction as the removal of oxygen or gain of electrons during extraction.
- Select carbon reduction or electrolysis for a named metal using its position in the reactivity series.
Factors affecting braking distance 1
Adverse road conditions include wet or icy conditions. Poor condition of the vehicle is limited to the vehicle's brakes or tyres.
- Identify wet and icy conditions as examples of adverse road conditions that affect braking distance.
- Identify the vehicle's brakes and tyres as the parts whose poor condition affects braking distance.
- Explain how each named condition reduces friction or braking force and so increases braking distance.
Factors affecting braking distance 1
estimate how the distance required for road vehicles to stop in an emergency varies over a range of typical speeds.
- State and use the relationship stopping distance = thinking distance + braking distance.
- Describe how thinking distance and braking distance each change as speed increases.
- Estimate typical stopping distances at a range of speeds and justify why they are only estimates.
Factors affecting braking distance 1
explain the factors which affect the distance required for road transport vehicles to come to rest in emergencies, and the implications for safety
- Explain how speed, reaction time, friction and vehicle condition affect the distance needed to stop.
- Use energy and force ideas to justify why braking distance increases rapidly with speed.
- Assess how reducing speed and maintaining vehicles can reduce collision risk.
Factors affecting braking distance 1
The braking distance of a vehicle can be affected by adverse road and weather conditions and poor condition of the vehicle.
- State that braking distance is the distance travelled while the brakes are applied until the vehicle stops.
- Explain how adverse road and weather conditions reduce friction and increase braking distance.
- Explain how poor vehicle condition reduces braking force or grip and increases braking distance.
Factors affecting braking distance 2
(HT only) estimate the forces involved in the deceleration of road vehicles in typical situations on a public road.
- Calculate the deceleration of a vehicle from a stated speed and braking distance using v² = u² + 2as.
- Apply F = ma to convert a calculated deceleration into an estimated braking force.
- Evaluate whether an estimated force is realistic for a road vehicle in a typical public-road situation.
Factors affecting braking distance 2
explain the dangers caused by large decelerations WS 1.5
- Explain why large decelerations produce large forces on a vehicle and its occupants.
- Describe the dangers to passengers caused by inertia during rapid deceleration.
- Relate safety features such as seat belts and crumple zones to reduced deceleration and reduced injury risk.
Factors affecting braking distance 2
The greater the braking force the greater the deceleration of the vehicle. Large decelerations may lead to brakes overheating and/or loss of control.
- Describe the relationship between braking force and deceleration for a vehicle of constant mass.
- Explain how large decelerations can cause brake overheating or loss of control.
- Use force = mass × acceleration to calculate deceleration from a braking force.
Factors affecting braking distance 2
The greater the speed of a vehicle the greater the braking force needed to stop the vehicle in a certain distance.
- Describe how kinetic energy changes as vehicle speed changes.
- Use the work done by brakes relationship to compare braking forces at different speeds.
- Apply the speed-squared relationship to explain why higher speeds need much greater braking force.
Factors affecting braking distance 2
When a force is applied to the brakes of a vehicle, work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increases.
- Describe the energy transfer that occurs when a vehicle brakes.
- Use work done = force × distance to explain how friction reduces kinetic energy.
- Explain why the temperature of the brakes increases during braking.
Factors which affect the rates of chemical reactions
Factors which affect the rates of chemical reactions include: the concentrations of reactants in solution, the pressure of reacting gases, the surface area of solid reactants, the temperature and the presence of catalysts.
- State the factors that affect the rate of a chemical reaction.
- Explain how each factor changes collision frequency or collision energy to alter the rate.
- Apply collision theory to predict and justify changes in reaction rate in unfamiliar contexts.
Factors which affect the rates of chemical reactions
Required practical activity 11: investigate how changes in concentration affect the rates of reactions by a method involving measuring the volume of a gas produced and a method involving a change in colour or turbidity.
- Carry out a gas-volume method to compare rates at different concentrations.
- Carry out a turbidity method and use time for the cross to disappear as a measure of rate.
- Interpret rate data and explain results using collision theory.
Factors which affect the rates of chemical reactions
Students should be able to recall how changing these factors affects the rate of chemical reactions.
- Describe how temperature, concentration, pressure, surface area and catalysts affect the rate of a chemical reaction.
- Explain each effect in terms of collision frequency or collision energy.
- Apply the factors to unfamiliar reactions and predict whether the rate increases or decreases.
Factors which affect the rates of chemical reactions
This should be an investigation involving developing a hypothesis.
- Construct a testable hypothesis that predicts how a named factor affects the rate of a chemical reaction.
- Identify and control variables in a rates investigation to ensure a fair test.
- Justify a hypothesis using collision theory and explain how results would test the prediction.
Feedback systems (HT only)
Adrenaline is produced by the adrenal glands in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’.
- Identify the adrenal glands as the source of adrenaline and state when it is released.
- Describe how adrenaline increases heart rate and boosts oxygen and glucose delivery to the brain and muscles.
- Explain how these changes prepare the body for ‘flight or fight’ during fear or stress.
Feedback systems (HT only)
Students should be able to explain the roles of thyroxine and adrenaline in the body.
- State the gland that secretes thyroxine and the gland that secretes adrenaline.
- Describe how thyroxine controls basal metabolic rate and explain how negative feedback regulates its concentration (Higher Tier only).
- Explain how adrenaline prepares the body for ‘flight or fight’ by increasing heart rate and oxygen and glucose delivery.
Feedback systems (HT only)
Thyroxine from the thyroid gland stimulates the basal metabolic rate. It plays an important role in growth and development.
- State the thyroid gland as the source of thyroxine and describe its transport in the blood.
- Explain how thyroxine raises the basal metabolic rate and increases energy release at rest.
- Describe the role of thyroxine in growth and development and give a consequence of abnormal levels.
Feedback systems (HT only)
Thyroxine levels are controlled by negative feedback. WS 1.2, MS 2c
- Describe the sequence of hypothalamus, pituitary, TSH and thyroid in controlling thyroxine.
- Explain how rising thyroxine inhibits further release and why this is negative feedback.
- Apply the negative feedback loop to predict the effect of a change in thyroxine level.
Fleming's left-hand rule (HT only)
current, I, in amperes, A (amp is acceptable for ampere)
- State that current I is measured in amperes, A, and that amp is acceptable for ampere.
- Describe current as the rate of flow of charge and measure it with an ammeter in series.
- Apply the relationship F = B I L to explain how current affects the force on a conductor in a magnetic field.
Fleming's left-hand rule (HT only)
F = B I l
- Recall and use the equation F = B I l to calculate the force on a current-carrying conductor.
- Identify the meaning and SI unit of each symbol in the equation.
- Apply the condition that the conductor must be at right angles to the magnetic field for the equation to give the maximum force.
Fleming's left-hand rule (HT only)
For a conductor at right angles to a magnetic field and carrying a current:
- State the direction of the force on a current-carrying conductor at right angles to a magnetic field.
- Recall and apply the equation F = B I l to calculate the force on a conductor.
- Explain the effect of reversing the current or the magnetic field on the direction of the force.
Fleming's left-hand rule (HT only)
force = magnetic flux density × current × length
- Recall and use the equation force = magnetic flux density × current × length.
- Calculate the force on a current-carrying conductor in a magnetic field using correct units.
- Rearrange the equation to determine magnetic flux density, current or length.
Fleming's left-hand rule (HT only)
force, F, in newtons, N
- Identify F as force and state its SI unit, the newton (N).
- Explain that force is a vector and describe how its direction is found using Fleming's left-hand rule.
- Use the unit N correctly when reporting values calculated from F = B I l.
Fleming's left-hand rule (HT only)
length, l, in metres, m
- Identify the length l as the conductor length inside the magnetic field, measured in metres.
- Convert a length from centimetres or millimetres into metres correctly.
- Apply F = B I l with consistent SI units to find the force on a current-carrying conductor.
Fleming's left-hand rule (HT only)
magnetic flux density, B, in tesla, T
- State that magnetic flux density B is measured in tesla, T.
- Calculate magnetic flux density using B = F ÷ (I L) for a conductor perpendicular to a uniform field.
- Describe how the direction of the force depends on the directions of the current and the magnetic field.
Fleming's left-hand rule (HT only)
Students should be able to recall the factors that affect the size of the force on the conductor.
- List the factors that affect the size of the force on a current-carrying conductor in a magnetic field.
- Describe how changing current, magnetic flux density, length or angle changes the force.
- Use F = B I l to calculate the force when the conductor is perpendicular to the magnetic field.
Fleming's left-hand rule (HT only)
Students should be able to show that Fleming's left-hand rule represents the relative orientation of the force, the current in the conductor and the magnetic field.
- Label the first finger, second finger and thumb of Fleming's left-hand rule with field, current and force respectively.
- Apply the rule to a given arrangement to determine the direction of the force on a current-carrying conductor.
- Predict how reversing the current, the field or both changes the direction of the force.
Fleming's left-hand rule (HT only)
When a conductor carrying a current is placed in a magnetic field the magnet producing the field and the conductor exert a force on each other. This is called the motor effect.
- Describe the motor effect and the conditions under which it occurs.
- Use Fleming's left-hand rule to determine the direction of the force on a current-carrying conductor.
- Explain how reversing current or magnetic field affects the direction of the force.
Forces and elasticity
A force that stretches (or compresses) a spring does work and elastic potential energy is stored in the spring. Provided the spring is not inelastically deformed, the work done on the spring and the elastic potential energy stored are equal.
- Describe how a stretching or compressing force does work on a spring and stores elastic potential energy.
- Calculate work done and elastic potential energy using W = ½Fe and Ee = ½ke².
- Explain why work done equals elastic potential energy stored only when the spring is not inelastically deformed.
Forces and elasticity
calculate a spring constant in linear cases
- Rearrange F = k e to calculate the spring constant from a force and an extension.
- Convert extension measurements into metres and substitute them correctly into k = F ÷ e.
- Interpret the gradient of the linear section of a force–extension graph as the spring constant.
Forces and elasticity
calculate work done in stretching (or compressing) a spring (up to the limit of proportionality) using the equation:
- Calculate work done in stretching or compressing a spring using W = 0.5 × k × e².
- Convert extensions from centimetres to metres and square them correctly.
- Explain why the equation applies only up to the limit of proportionality.
Forces and elasticity
describe the difference between a linear and non-linear relationship between force and extension
- Describe the shape of linear and non-linear force–extension graphs.
- Explain the link between a linear graph through the origin, direct proportionality and Hooke's law.
- Identify from a graph whether a spring has exceeded its limit of proportionality.
Forces and elasticity
describe the difference between elastic deformation and inelastic deformation caused by stretching forces.
- State what happens to an object after the stretching force is removed in elastic deformation.
- State what happens to an object after the stretching force is removed in inelastic deformation.
- Use examples to distinguish elastic from inelastic deformation in terms of recovery of original length and shape.
Forces and elasticity
Eₑ = ½ke²
- Recall and apply the equation Eₑ = ½ke² to calculate elastic potential energy.
- Convert between units of length and identify the extension of a spring from given data.
- Describe the energy transfer when a stretched spring is released.
Forces and elasticity
elastic potential energy = 0.5 × spring constant × extension ²
- Use Ee = 0.5 × k × e² to calculate elastic potential energy.
- Rearrange the equation to find spring constant or extension.
- Interpret the equation as the area under a force–extension graph within the limit of proportionality.
Forces and elasticity
explain why, to change the shape of an object (by stretching, bending or compressing), more than one force has to be applied – this is limited to stationary objects only
- Explain why one force would move a stationary object.
- Describe how two balanced forces deform an object without moving it.
- Apply the idea of zero resultant force to stretching, bending and compression.
Forces and elasticity
extension, e, in metres, m
- Define extension as the increase in length of an elastic object and state its unit as the metre.
- Calculate extension from measured stretched and original lengths, converting units where necessary.
- Explain why extension, not total length, is used in the force–extension relationship.
Forces and elasticity
F = k e
- Use F = k e and its rearrangements to solve numerical problems accurately.
- Interpret the gradient of a force–extension graph as the spring constant.
- Explain the meaning of the spring constant and the limits of the relationship.
Forces and elasticity
force = spring constant × extension
- Apply force = spring constant × extension to calculate any one variable when the other two are known.
- Determine extension correctly from original and stretched lengths, converting units to metres.
- Describe the conditions under which the relationship is valid and interpret a force–extension graph.
Forces and elasticity
force, F, in newtons, N
- State that force is measured in newtons and is a vector quantity.
- Apply the equation F = k × e to calculate force, spring constant or extension.
- Distinguish between mass in kilograms and force in newtons when solving elasticity problems.
Forces and elasticity
give examples of the forces involved in stretching, bending or compressing an object
- Identify two opposing forces in a stretching example.
- Describe the direction of forces in a compression example.
- Explain how forces at different points produce bending.
Forces and elasticity
interpret data from an investigation of the relationship between force and extension
- Calculate extension from total length and original length for each set of readings.
- Describe the relationship between force and extension using the shape of the graph, including the linear region and the limit of proportionality.
- Use the gradient of the linear section to determine the spring constant and comment on anomalous results.
Forces and elasticity
Required practical activity 18: investigate the relationship between force and extension for a spring.
- Carry out the practical safely to obtain paired values of force and extension for a spring.
- Plot and interpret a force-extension graph, identifying the straight section and the limit of proportionality.
- Calculate the spring constant from the gradient of the straight section and use F = kx.
Forces and elasticity
spring constant, k, in newtons per metre, N/m
- Define the spring constant and state its unit as N/m.
- Calculate the spring constant using k = F ÷ e with consistent SI units.
- Determine the spring constant from the gradient of a force–extension graph in the linear region.
Forces and elasticity
Students should be able to calculate relevant values of stored energy and energy transfers.
- Rearrange and apply Eₑ = ½ke² to find stored energy, spring constant or extension.
- Describe the energy transfers that occur when a stretched spring is released.
- Check that calculated values are consistent with the spring remaining within its elastic limit.
Forces and elasticity
The extension of an elastic object, such as a spring, is directly proportional to the force applied, provided that the limit of proportionality is not exceeded.
- Define extension and state the condition under which extension is directly proportional to the applied force.
- Use the equation F = k × e to calculate force, extension or spring constant with correct units.
- Interpret a force-extension graph to identify the limit of proportionality and explain why the relationship fails beyond it.
Forces and elasticity
This relationship also applies to the compression of an elastic object, where ‘e’ would be the compression of the object.
- Describe how the force–extension relationship applies to compression of an elastic object.
- Calculate compression from original and compressed lengths using consistent units.
- Apply the equation force = spring constant × compression to solve problems involving squashed elastic objects.
Formulations
A formulation is a mixture that has been designed as a useful product. Many products are complex mixtures in which each chemical has a particular purpose. Formulations are made by mixing the components in carefully measured quantities to ensure that the product has the required properties. Formulations include fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods.
- Define a formulation as a designed mixture made from components in carefully measured quantities.
- Explain how the purpose of each component and its proportion contribute to the required properties of a product.
- Classify given products, such as fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods, as formulations using appropriate information.
Formulations
Students should be able to identify formulations given appropriate information.
- Recognise a formulation from information about its components, purposes and measured quantities.
- Distinguish formulations from pure substances and from mixtures that are not designed products.
- Explain, using supplied information, why a chosen material meets the definition of a formulation.
Fossils
as preserved traces of organisms, such as footprints, burrows and rootlet traces.
- State that trace fossils are preserved traces of organism activity, giving footprints, burrows and rootlet traces as examples.
- Describe how a footprint, burrow or rootlet trace can be preserved in sedimentary rock.
- Explain what trace fossils can reveal about an organism that a body fossil might not.
Fossils
Fossils are the ‘remains’ of organisms from millions of years ago, which are found in rocks.
- Define a fossil as preserved evidence of an organism from millions of years ago.
- Describe how fossils are found in rocks, particularly sedimentary rock.
- Give an example of a fossil and explain why its remains were preserved.
Fossils
Fossils may be formed:
- Describe at least two ways in which fossils may be formed.
- Explain how conditions such as rapid burial or low temperature prevent decay.
- Distinguish between body fossils, moulds, casts and trace fossils.
Fossils
from parts of organisms that have not decayed because one or more of the conditions needed for decay are absent
- State the conditions microorganisms need for decay.
- Explain how the absence of one or more of these conditions can preserve parts of organisms.
- Apply this explanation to named examples such as amber, ice or bog preservation.
Fossils
Many early forms of life were soft-bodied, which means that they have left few traces behind. What traces there were have been mainly destroyed by geological activity. This is why scientists cannot be certain about how life began on Earth.
- Explain why soft-bodied early organisms left few fossil traces.
- Describe how geological activity destroys fossils and creates gaps in the fossil record.
- Explain why the origin of life on Earth cannot be stated with certainty from the available evidence.
Fossils
Students should be able to extract and interpret information from charts, graphs and tables such as evolutionary trees.
- Identify common ancestors and closest relatives from an evolutionary tree.
- Read and quote values accurately from a chart, graph or table about fossils or species.
- Use data from a chart, graph or table to justify a conclusion about evolutionary relationships.
Fossils
We can learn from fossils how much or how little different organisms have changed as life developed on Earth.
- Compare a named fossil with its living relative and state whether the organism has changed much or little.
- Use fossil evidence to describe how a lineage changed as life developed on Earth.
- Explain how fossils provide evidence that some organisms have become extinct.
Fossils
when parts of the organism are replaced by minerals as they decay
- Describe how minerals replace parts of an organism during fossil formation.
- Explain why hard parts are more likely than soft parts to be preserved in this way.
- Relate mineral replacement to the formation of fossils in sedimentary rock.
Fractional distillation and petrochemicals
Many of the fuels on which we depend for our modern lifestyle, such as petrol, diesel oil, kerosene, heavy fuel oil and liquefied petroleum gases, are produced from crude oil.
- Name the main fractions obtained from crude oil, including petrol, diesel oil, kerosene, heavy fuel oil and liquefied petroleum gases.
- Describe how fractional distillation separates crude oil into fractions with different boiling point ranges.
- Explain how the size of hydrocarbon molecules affects boiling point, volatility, viscosity and ease of burning, and link this to the use of each fraction as a fuel.
Fractional distillation and petrochemicals
Many useful materials on which modern life depends are produced by the petrochemical industry, such as solvents, lubricants, polymers, detergents.
- Identify solvents, lubricants, polymers and detergents as useful materials produced by the petrochemical industry.
- Describe the function of each type of petrochemical product and give a common example of its use.
- Explain that crude oil fractions are used as feedstocks to make many materials on which modern life depends, not only fuels.
Fractional distillation and petrochemicals
Students should be able to explain how fractional distillation works in terms of evaporation and condensation.
- Describe the sequence of evaporation, rising, cooling and condensation in fractional distillation.
- Relate the boiling point of a hydrocarbon to where it is collected in the column.
- Explain why each fraction is a mixture rather than a pure substance.
Fractional distillation and petrochemicals
The fractions can be processed to produce fuels and feedstock for the petrochemical industry.
- Describe how fractions from crude oil are processed into fuels and feedstock.
- Explain the role of cracking in producing useful alkenes for the petrochemical industry.
- Give examples of products made from fractions and from cracked hydrocarbons.
Fractional distillation and petrochemicals
The many hydrocarbons in crude oil may be separated into fractions, each of which contains molecules with a similar number of carbon atoms, by fractional distillation.
- Describe how crude oil is separated into fractions by fractional distillation.
- Explain why fractions condense at different heights in the fractionating column.
- Relate the number of carbon atoms in a hydrocarbon molecule to its boiling point.
Fractional distillation and petrochemicals
The vast array of natural and synthetic carbon compounds occur due to the ability of carbon atoms to form families of similar compounds.
- Describe how carbon's four covalent bonds allow chains, branches and rings to form.
- Identify a homologous series from its general formula and a named member.
- Classify given carbon compounds as natural or synthetic and justify the classification.
Fungal diseases
Rose black spot is a fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early. It affects the growth of the plant as photosynthesis is reduced. It is spread in the environment by water or wind. Rose black spot can be treated by using fungicides and/or removing and destroying the affected leaves.
- Describe the symptoms of rose black spot and identify the pathogen as a fungus.
- Explain how leaf loss caused by rose black spot reduces photosynthesis and plant growth.
- State that rose black spot spreads by water or wind and describe how fungicides and removal of affected leaves control it.
Genetic engineering
(HT only) Students should be able to describe the main steps in the process of genetic engineering.
- Describe the main steps in the process of genetic engineering.
- Identify that enzymes are used to isolate the required gene and insert it into a vector.
- Explain the role of a vector, such as a plasmid or virus, in transferring genes to recipient cells at an early stage of development.
Genetic engineering
Bacterial cells have been genetically engineered to produce useful substances such as human insulin to treat diabetes.
- Describe how a human gene can be transferred into a bacterial cell using a vector.
- Explain how genetically engineered bacteria produce human insulin.
- Relate the large-scale growth of bacteria to the supply of a useful medicinal product.
Genetic engineering
Concerns about GM crops include the effect on populations of wild flowers and insects. Some people feel the effects of eating GM crops on human health have not been fully explored.
- Describe how growing herbicide-resistant GM crops can reduce populations of wild flowers and insects.
- Explain how a fall in insect populations can affect other organisms in a food chain.
- Discuss the concern that the effects of eating GM crops on human health have not been fully explored.
Genetic engineering
Crops that have had their genes modified in this way are called genetically modified (GM) crops. GM crops include ones that are resistant to insect attack or to herbicides. GM crops generally show increased yields.
- Define a genetically modified (GM) crop.
- Describe examples of GM crops resistant to insect attack or to herbicides.
- Explain why GM crops generally show increased yields.
Genetic engineering
enzymes are used to isolate the required gene; this gene is inserted into a vector, usually a bacterial plasmid or a virus
- Describe how enzymes are used to isolate a required gene from DNA.
- Identify bacterial plasmids and viruses as vectors and state their function.
- Explain how an isolated gene is inserted into a vector to form recombinant DNA.
Genetic engineering
genes are transferred to the cells of animals, plants or microorganisms at an early stage in their development so that they develop with desired characteristics.
- Describe how a gene is transferred into the cells of an animal, plant or microorganism.
- Explain why transfer at an early stage of development causes the whole organism to develop the desired characteristic.
- Apply the process to a named example, such as insulin production in bacteria or pest-resistant crops.
Genetic engineering
In genetic engineering, genes from the chromosomes of humans and other organisms can be ‘cut out’ and transferred to cells of other organisms.
- Define genetic engineering as the transfer of a gene from one organism to another.
- Describe how enzymes are used to cut out a gene from a chromosome.
- Explain how transferring a gene can give an organism a desired characteristic, using human insulin as an example.
Genetic engineering
Modern medical research is exploring the possibility of genetic modification to overcome some inherited disorders.
- Describe how a faulty allele causes an inherited disorder.
- Explain the concept of using genetic modification to insert a normal allele into a patient's cells.
- Discuss the ethical and safety considerations of using genetic modification to treat inherited disorders.
Genetic engineering
Plant crops have been genetically engineered to be resistant to diseases or to produce bigger better fruits.
- Describe how crop plants have been genetically engineered for disease resistance.
- Describe how crop plants have been genetically engineered to produce bigger or better fruits.
- Explain that these characteristics result from an introduced gene being expressed in the plant.
Genetic engineering
Students should be able to describe genetic engineering as a process which involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic.
- Describe genetic engineering as modification of an organism's genome by introducing a gene from another organism.
- Sequence the main steps of cutting out a gene, inserting it into a vector and transferring it to a recipient cell.
- Link a transferred gene to the desired characteristic produced in the recipient organism.
Genetic engineering
Students should be able to explain the potential benefits and risks of genetic engineering in agriculture and in medicine and that some people have objections.
- Explain potential benefits and risks of genetic engineering in agriculture and medicine.
- Describe reasons why some people object to genetic engineering.
- Evaluate competing arguments to reach a supported conclusion about genetic engineering.
Genetic engineering
the vector is used to insert the gene into the required cells
- Describe how a vector inserts a gene into required cells.
- Explain that the host cell expresses the inserted gene to make the desired protein.
- Relate the choice of vector to the type of host cell being modified.
Genetic inheritance
(HT only) Students should be able to construct a genetic cross by Punnett square diagram and use it to make predictions using the theory of probability.
- Construct a Punnett square for a given genetic cross at Higher tier.
- Calculate the probability of a named genotype or phenotype from the completed square.
- Explain why a predicted probability does not determine the exact outcome for a small number of offspring.
Genetic inheritance
A dominant allele is always expressed, even if only one copy is present. A recessive allele is only expressed if two copies are present (therefore no dominant allele present).
- Distinguish dominant and recessive alleles by when each is expressed.
- Complete a genetic diagram for a monohybrid cross and identify offspring genotypes.
- Predict phenotype ratios and explain them using dominance.
Genetic inheritance
allele
- Define an allele as a version of a gene.
- Describe how alleles are inherited from both parents.
- Use alleles correctly in genetic diagrams and probability calculations.
Genetic inheritance
chromosome
- State that chromosomes are found in the nucleus and are made of DNA.
- Describe the diploid number 46 and the haploid number 23 in humans.
- Explain how chromosome pairs are inherited from both parents and how sex chromosomes determine sex.
Genetic inheritance
dominant
- Define a dominant allele and explain its effect in a heterozygote.
- Use capital and lower-case letters correctly in genetic diagrams.
- Predict the probability of offspring showing a dominant characteristic from parental genotypes.
Genetic inheritance
gamete
- Define gamete and state that gametes are haploid sex cells.
- Explain how gametes are produced by meiosis and carry one allele from each pair.
- Describe fertilisation as the fusion of two gametes to form a diploid zygote.
Genetic inheritance
gene
- Define a gene as a section of DNA that codes for a protein.
- Describe the relationship between a gene, its locus and its alleles.
- Explain how a mutation in a gene can lead to a change in the protein produced.
Genetic inheritance
genotype
- State that genotype is the combination of alleles for a gene.
- Represent genotypes using standard dominant and recessive allele notation.
- Distinguish genotype from phenotype in genetic crosses.
Genetic inheritance
heterozygous
- State that heterozygous means two different alleles of a gene.
- Use correct allele notation to represent a heterozygote.
- Predict the phenotype of a heterozygote using dominance.
Genetic inheritance
homozygous
- Define homozygous and identify homozygous genotypes from a genetic diagram.
- Distinguish homozygous dominant from homozygous recessive and link each to its phenotype.
- Predict offspring ratios from crosses involving homozygous parents.
Genetic inheritance
If the two alleles present are the same the organism is homozygous for that trait, but if the alleles are different they are heterozygous.
- Define homozygous and heterozygous using the terms allele, genotype and phenotype correctly.
- Classify given genotypes such as AA, Aa and aa as homozygous or heterozygous and state the phenotype where dominance is known.
- Construct and interpret a simple monohybrid cross to identify homozygous and heterozygous offspring.
Genetic inheritance
Most characteristics are a result of multiple genes interacting, rather than a single gene.
- Describe polygenic inheritance as the control of a characteristic by multiple genes interacting.
- Explain why polygenic characteristics show continuous variation rather than distinct categories.
- Evaluate why simple single-gene crosses do not represent most inherited characteristics.
Genetic inheritance
phenotype.
- Define phenotype as the observable characteristic of an organism.
- Determine the phenotype from a given genotype using dominance rules.
- Explain how environmental factors can alter phenotype without changing genotype.
Genetic inheritance
recessive
- Define a recessive allele and state the condition under which it is expressed.
- Use a genetic diagram to predict the probability of a recessive phenotype from given parental genotypes.
- Explain how a recessive characteristic can appear in offspring of parents who do not show it.
Genetic inheritance
Some characteristics are controlled by a single gene, such as: fur colour in mice; and red-green colour blindness in humans. Each gene may have different forms called alleles.
- Define gene and allele and distinguish between them.
- Describe single-gene inheritance using fur colour in mice and red-green colour blindness.
- Use correct allele notation to represent dominant, recessive, homozygous and heterozygous genotypes.
Genetic inheritance
Students should be able to complete a Punnett square diagram and extract and interpret information from genetic crosses and family trees.
- Complete a Punnett square accurately from given parental genotypes.
- Extract genotype and phenotype ratios from a completed genetic cross.
- Interpret a family tree to deduce the genotypes of named individuals.
Genetic inheritance
Students should be able to explain the terms:
- State the meaning of gene, gamete, chromosome, allele, genotype, phenotype, homozygous, heterozygous, dominant and recessive.
- Apply the terms correctly when interpreting a genetic cross or pedigree.
- Explain how alleles interact to produce a phenotype in a named example.
Genetic inheritance
Students should be able to understand the concept of probability in predicting the results of a single gene cross, but recall that most phenotype features are the result of multiple genes rather than single gene inheritance.
- Calculate the probability of a genotype or phenotype from a single gene cross.
- Explain why observed offspring numbers may differ from predicted ratios.
- Describe why most phenotype features are polygenic rather than controlled by a single gene.
Genetic inheritance
Students should be able to use direct proportion and simple ratios to express the outcome of a genetic cross.
- Write the genotype and phenotype ratios from a completed Punnett square.
- Convert a genetic ratio into proportions as fractions or percentages using direct proportion.
- Explain the difference between a ratio and a proportion in the context of a genetic cross.
Genetic inheritance
The alleles present, or genotype, operate at a molecular level to develop characteristics that can be expressed as a phenotype.
- Define genotype and phenotype and use both terms accurately.
- Explain how an allele codes for a polypeptide that contributes to a characteristic.
- Apply the allele-to-protein-to-phenotype sequence to an unfamiliar example.
Giant covalent structures
Students should be able to recognise giant covalent structures from diagrams showing their bonding and structure.
- Identify from a diagram whether a substance has a giant covalent structure rather than a simple molecular structure.
- Describe the bonding pattern in diamond, graphite and silicon dioxide using the diagram provided.
- Relate a feature of the giant covalent structure to a physical property such as melting point, hardness or electrical conductivity.
Giant covalent structures
Substances that consist of giant covalent structures are solids with very high melting points. All of the atoms in these structures are linked to other atoms by strong covalent bonds. These bonds must be overcome to melt or boil these substances. Diamond and graphite (forms of carbon) and silicon dioxide (silica) are examples of giant covalent structures.
- Describe the structure and bonding in giant covalent substances such as diamond, graphite and silicon dioxide.
- Explain why giant covalent substances have very high melting points in terms of breaking strong covalent bonds.
- Identify examples of giant covalent structures from diagrams or descriptions.
Global climate change
An increase in average global temperature is a major cause of climate change.
- State that average global temperature is a long-term global mean derived from many measurements.
- Explain how a rise in average global temperature leads to melting ice, sea level rise and changed weather patterns.
- Distinguish between a weather event and a change in climate using the idea of long-term patterns.
Global climate change
describe briefly four potential effects of global climate change
- State four potential effects of global climate change.
- Explain the mechanism linking each effect to global warming.
- Distinguish between climate change effects and their causes.
Global climate change
discuss the scale, risk and environmental implications of global climate change.
- Explain the scale of global climate change in space and time.
- Evaluate risk by combining likelihood and severity of effects.
- Analyse environmental implications and distinguish mitigation from adaptation.
Global climate change
There are several potential effects of global climate change.
- State that global climate change has several potential effects.
- Describe at least two effects on the environment or people.
- Explain how one effect results from rising global temperatures.
Global warming
Levels of carbon dioxide and methane in the atmosphere are increasing, and contribute to ‘global warming’.
- Identify carbon dioxide and methane as greenhouse gases whose atmospheric levels are increasing.
- Describe at least one human activity that increases carbon dioxide and one that increases methane.
- Explain how increasing greenhouse gas levels contribute to global warming by absorbing infrared radiation.
Global warming
Students should be able to describe some of the biological consequences of global warming.
- State at least two biological consequences of global warming, each linked to a named organism or ecosystem.
- Describe how a physical change caused by global warming affects the survival or distribution of a species.
- Explain why some species may become endangered or extinct as a result of global warming.
Graphene and fullerenes
Carbon nanotubes are cylindrical fullerenes with very high length to diameter ratios. Their properties make them useful for nanotechnology, electronics and materials.
- Describe the cylindrical structure of carbon nanotubes and their very high length to diameter ratio.
- Relate the properties of carbon nanotubes, including conductivity and strength, to their bonding and nanoscale structure.
- Explain how the properties of carbon nanotubes make them useful in nanotechnology, electronics and materials.
Graphene and fullerenes
Fullerenes are molecules of carbon atoms with hollow shapes. The structure of fullerenes is based on hexagonal rings of carbon atoms but they may also contain rings with five or seven carbon atoms. The first fullerene to be discovered was Buckminsterfullerene (C₆₀) which has a spherical shape.
- Describe fullerenes as hollow molecular forms of carbon based on hexagonal rings with possible five- or seven-membered rings.
- Identify Buckminsterfullerene as C₆₀, the first fullerene discovered, and describe its spherical shape.
- Explain how the molecular structure of fullerenes affects their physical properties and suggest a use such as drug delivery.
Graphene and fullerenes
give examples of the uses of fullerenes, including carbon nanotubes.
- State at least two uses of fullerenes, including carbon nanotubes, such as drug delivery, lubricants, composites, electronics and hydrogen storage.
- Link each named use to a property of the fullerene, such as hollow cage shape, high strength, low mass, electrical conductivity or large surface area.
- Distinguish uses of fullerenes from uses of other carbon allotropes such as diamond and graphite.
Graphene and fullerenes
Graphene is a single layer of graphite and has properties that make it useful in electronics and composites.
- Describe graphene as a single layer of graphite with a hexagonal lattice.
- Explain how the structure of graphene gives it high electrical conductivity and strength.
- Relate the properties of graphene to its uses in electronics and composites.
Graphene and fullerenes
recognise graphene and fullerenes from diagrams and descriptions of their bonding and structure
- Identify graphene from a diagram or description as a single hexagonal sheet of carbon atoms one atom thick.
- Identify fullerenes, including C₆₀ and carbon nanotubes, from diagrams or descriptions as closed cage or cylindrical carbon molecules.
- Explain how the discrete, finite molecular structure distinguishes fullerenes from the continuous giant covalent lattice of graphene.
Graphene and fullerenes
Students should be able to explain the properties of graphene in terms of its structure and bonding.
- Describe the structure of graphene as a single layer of graphite one atom thick.
- Relate the bonding and delocalised electrons in graphene to its strength, conductivity, transparency and low mass.
- Apply knowledge of graphene's properties to justify a named use such as touchscreens or composite materials.
Graphite
In graphite, each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings which have no covalent bonds between the layers.
- Describe the structure of graphite as layers of hexagonal rings in which each carbon atom forms three covalent bonds.
- Explain why graphite has a high melting point but is soft and slippery, referring to bonding within and forces between layers.
- Explain why graphite conducts electricity in terms of delocalised electrons.
Graphite
In graphite, one electron from each carbon atom is delocalised.
- Describe the bonding in a graphite layer, including the number of covalent bonds formed by each carbon atom.
- Identify that one electron per carbon atom is delocalised in graphite.
- Relate delocalised electrons in graphite to its ability to conduct electricity.
Graphite
Students should be able to explain the properties of graphite in terms of its structure and bonding.
- Describe the structure of graphite, including its hexagonal layers and the bonding within and between layers.
- Explain how the strength of covalent bonds and the weakness of forces between layers account for the melting point, softness and density of graphite.
- Explain how delocalised electrons in graphite allow it to conduct electricity.
Graphite
Students should know that graphite is similar to metals in that it has delocalised electrons.
- Describe the bonding in graphite, including that each carbon atom forms three covalent bonds.
- Explain how delocalised electrons allow graphite to conduct electricity.
- Compare the conduction mechanism in graphite with that in metals.
Gravity
gravitational field strength, g, in newtons per kilogram, N/kg (In any calculation the value of the gravitational field strength (g) will be given.)
- Define gravitational field strength and state its unit as N/kg.
- Use a given value of g in W = m × g to calculate weight in newtons.
- Compare the weight of the same mass on different planets or moons using their g values.
Gravity
mass, m, in kilograms, kg
- Identify mass as a quantity measured in kilograms and recognise its symbol m.
- Convert a mass given in grams into kilograms correctly.
- Substitute a mass in kg into W = m × g and state the resulting weight in newtons.
Gravity
The weight of an object and the mass of an object are directly proportional.
- State the equation linking weight, mass and gravitational field strength and use it to calculate any one of the three quantities.
- Interpret a graph of weight against mass, including identifying the gradient as gravitational field strength.
- Explain why mass remains constant while weight changes when gravitational field strength changes.
Gravity
The weight of an object can be calculated using the equation:
- Recall the equation weight = mass × gravitational field strength.
- Use the equation to calculate weight, mass or gravitational field strength when two values are known.
- Distinguish between mass in kilograms and weight in newtons in written answers.
Gravity
The weight of an object depends on the gravitational field strength at the point where the object is.
- Use the equation W = m × g to calculate weight given mass and gravitational field strength.
- Explain why the weight of an object changes when gravitational field strength changes, while mass remains constant.
- Compare the weight of an object on Earth with its weight on another planet or moon using appropriate values of g.
Gravity
The weight of an object may be considered to act at a single point referred to as the object’s ‘centre of mass’.
- Define the centre of mass and describe how to locate it for a uniform or symmetrical object.
- Use the centre of mass to represent the weight of an object as a single force in moment and equilibrium calculations.
- Explain how the position of the centre of mass affects the stability of an object.
Gravity
W = m g
- Use the equation W = m g to calculate weight, mass or gravitational field strength.
- Describe the difference between mass in kilograms and weight in newtons.
- Explain why an object's weight changes with gravitational field strength while its mass stays the same.
Gravity
weight = mass × gravitational field strength
- Use weight = mass × gravitational field strength to calculate any one of the three quantities.
- Explain why weight changes with gravitational field strength while mass remains constant.
- Apply the equation to compare weights on different planets or moons.
Gravity
Weight is measured using a calibrated spring-balance (a newtonmeter).
- Identify that weight is measured using a calibrated spring-balance (newtonmeter).
- Describe how to use a spring-balance to measure the weight of an object accurately.
- Explain why the reading on a spring-balance changes with gravitational field strength while mass remains constant.
Gravity
Weight is the force acting on an object due to gravity. The force of gravity close to the Earth is due to the gravitational field around the Earth.
- Define weight as the force acting on an object due to gravity and state its unit.
- Distinguish between mass and weight in terms of definition and unit.
- Describe the Earth's gravitational field and explain that it causes the force of gravity close to the Earth.
Gravity
weight, W, in newtons, N
- Define weight as the gravitational force on an object and state its unit as the newton (N).
- Distinguish between mass and weight in terms of quantity, unit and dependence on location.
- Calculate weight using W = m g and interpret the result as a force in newtons.
Greenhouse gases
Greenhouse gases in the atmosphere maintain temperatures on Earth high enough to support life. Water vapour, carbon dioxide and methane are greenhouse gases.
- State that water vapour, carbon dioxide and methane are greenhouse gases.
- Explain how greenhouse gases absorb and re-emit infrared radiation to maintain Earth's temperature.
- Describe why the natural greenhouse effect is essential for life on Earth.
Greenhouse gases
Students should be able to describe the greenhouse effect in terms of the interaction of short and long wavelength radiation with matter.
- Describe the pathway of short wavelength solar radiation to the Earth's surface and its absorption.
- Describe how the warmed surface emits long wavelength infrared radiation.
- Explain how greenhouse gases absorb and re-radiate infrared radiation, warming the surface.
Group 0
explain how properties of the elements in Group 0 depend on the outer shell of electrons of the atoms
- State the number of electrons in the outer shell of helium and of other Group 0 elements.
- Explain why a full outer shell leads to low reactivity and monatomic behaviour.
- Relate the weak intermolecular forces between noble gas atoms to their low melting and boiling points.
- Use the full outer shell model to predict and explain trends down Group 0.
Group 0
predict properties from given trends down the group.
- Describe the trends in boiling point and density down Group 0.
- Explain the trends in terms of atomic size and intermolecular forces.
- Use given data to predict the properties of an unfamiliar noble gas.
- Distinguish between physical trends and the lack of chemical reactivity in Group 0.
Group 0
The boiling points of the noble gases increase with increasing relative atomic mass (going down the group).
- Describe the trend in boiling points of the noble gases down Group 0.
- Explain the trend in terms of increasing relative atomic mass, more electrons and stronger intermolecular forces.
- Apply the trend to compare the boiling points of two named noble gases using data.
Group 0
The elements in Group 0 of the periodic table are called the noble gases. They are unreactive and do not easily form molecules because their atoms have stable arrangements of electrons. The noble gases have eight electrons in their outer shell, except for helium, which has only two electrons.
- State that Group 0 elements are the noble gases and list examples.
- Explain why noble gases are unreactive in terms of their full outer electron shells.
- Describe the electron arrangement of helium and the other noble gases, noting helium's two-electron exception.
Group 1
explain how properties of the elements in Group 1 depend on the outer shell of electrons of the atoms
- Describe the electron configuration of Group 1 atoms and the ion they form.
- Explain how distance from the nucleus and shielding affect the loss of the outer electron.
- Relate the outer electron to trends in reactivity and melting point down Group 1.
Group 1
In Group 1, the reactivity of the elements increases going down the group.
- Describe the trend in reactivity of Group 1 metals down the group.
- Explain the trend in terms of distance from the nucleus and shielding of the outer electron.
- Relate the trend to observations of Group 1 metals reacting with water.
Group 1
predict properties from given trends down the group.
- Identify the direction of a trend from given data or information.
- Predict a property for a named Group 1 element using the trend.
- Justify a prediction by referring to the outer electron and atomic structure.
Group 1
Students should be able to describe the reactions of the first three alkali metals with oxygen, chlorine and water.
- Describe the reactions of lithium, sodium and potassium with oxygen, chlorine and water.
- Write word and balanced symbol equations for these reactions.
- Compare the vigour of the reactions of lithium, sodium and potassium and relate this to the trend in reactivity.
Group 1
The elements in Group 1 of the periodic table are known as the alkali metals and have characteristic properties because of the single electron in their outer shell.
- State that Group 1 elements have one electron in their outer shell and form 1⁺ ions.
- Explain how the single outer electron causes the characteristic physical and chemical properties of alkali metals.
- Describe and explain the trend in reactivity down Group 1 using atomic radius and shielding.
Group 7
A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt.
- Describe displacement reactions between halogens and aqueous solutions of halide salts.
- Explain displacement in terms of the reactivity trend down Group 7.
- Write balanced equations for halogen displacement reactions and identify the halogen formed from colour changes.
Group 7
explain how properties of the elements in Group 7 depend on the outer shell of electrons of the atoms
- Describe the outer-shell electron configuration of Group 7 atoms and the 1⁻ ion they form.
- Explain how the outer shell accounts for the reactivity and bonding of halogens.
- Relate the decrease in reactivity down Group 7 to increasing distance and shielding of the outer shell.
Group 7
In Group 7, the further down the group an element is the higher its relative molecular mass, melting point and boiling point.
- State that Group 7 elements exist as diatomic molecules and that relative molecular mass increases down the group.
- Explain that increased molecular size leads to stronger London dispersion forces between molecules.
- Relate stronger intermolecular forces to higher melting points and boiling points and to the observed states at room temperature.
Group 7
In Group 7, the reactivity of the elements decreases going down the group.
- Describe that Group 7 reactivity decreases down the group.
- Explain the trend in terms of electron gain, atomic radius and shielding.
- Use the trend to predict and interpret displacement reactions between halogens and halide ions.
Group 7
predict properties from given trends down the group.
- Describe the trends in melting point, colour and reactivity down Group 7.
- Use trends from known halogens to predict properties of less familiar halogens such as astatine.
- Justify predictions by referring to outer-shell electrons and distance from the nucleus.
Group 7
Students should be able to describe the nature of the compounds formed when chlorine, bromine and iodine react with metals and non-metals.
- Describe the ionic compounds formed when chlorine, bromine or iodine reacts with a metal.
- Describe the covalent compounds formed when a halogen reacts with a non-metal such as hydrogen.
- Explain how electron transfer or sharing allows the halogen atom to complete its outer shell.
Group 7
The elements in Group 7 of the periodic table are known as the halogens and have similar reactions because they all have seven electrons in their outer shell. The halogens are non-metals and consist of molecules made of pairs of atoms.
- State that Group 7 elements are the halogens and identify their position in the periodic table.
- Explain that halogens react similarly because each atom has seven outer-shell electrons.
- Describe halogens as non-metals that form diatomic molecules such as Cl₂ and Br₂.
Half-lives and the random nature of radioactive decay
(HT only) Students should be able to calculate the net decline, expressed as a ratio, in a radioactive emission after a given number of half-lives.
- Determine the number of half-lives from a given time and half-life.
- Calculate the remaining fraction or final emission after n half-lives using (1/2)ⁿ.
- Express the net decline as a simplified ratio in the form 1:2ⁿ.
Half-lives and the random nature of radioactive decay
Radioactive decay is random.
- Describe radioactive decay as a random process affecting individual nuclei.
- Explain how the random decay of many nuclei produces a predictable half-life pattern.
- Calculate the expected count rate or activity after a given number of half-lives.
Half-lives and the random nature of radioactive decay
Students should be able to determine the half-life of a radioactive isotope from given information.
- Identify the initial count rate or activity from given data, a graph or a table.
- Determine the half-life by halving the count rate and reading the corresponding time, including cases requiring repeated halving.
- State the half-life with the correct unit and explain that it is constant for a given isotope.
Half-lives and the random nature of radioactive decay
Students should be able to explain the concept of half-life and how it is related to the random nature of radioactive decay.
- Explain why radioactive decay is random for individual nuclei.
- Explain how a large sample produces a predictable half-life despite random decay.
- Relate half-life to a suitable use such as dating or medical tracing.
Half-lives and the random nature of radioactive decay
The half-life of a radioactive isotope is the time it takes for the number of nuclei of the isotope in a sample to halve, or the time it takes for the count rate (or activity) from a sample containing the isotope to fall to half its initial level.
- Define half-life in terms of nuclei number and in terms of count rate or activity.
- Apply repeated halving to find the activity or number of nuclei remaining after a given number of half-lives.
- Explain why random decay still produces a predictable half-life for a large sample.
Health issues
Defects in the immune system mean that an individual is more likely to suffer from infectious diseases.
- Describe how the immune system defends the body against pathogens.
- Explain why a defect in the immune system increases the likelihood of infectious disease.
- Give named examples of inherited, acquired or treatment-related immune defects.
Health issues
Different types of disease may interact.
- State that different types of disease can interact and give at least one named example.
- Explain how one disease can increase the risk or severity of another disease.
- Distinguish between communicable and non-communicable diseases when describing interactions.
Health issues
Diseases, both communicable Communicable diseases (page 35) and non-communicable, are major causes of ill health. Other factors including diet, stress and life situations may have a profound effect on both physical and mental health.
- Distinguish communicable from non-communicable diseases with named examples.
- Describe how diet, stress and life situations can affect physical and mental health.
- Explain how risk factors can interact to increase the chance of ill health.
Health issues
Health is the state of physical and mental well-being.
- State the full definition of health including physical and mental well-being.
- Describe examples of physical and mental factors that affect health.
- Explain how physical and mental well-being can influence each other in a named case.
Health issues
Immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma.
- Describe how an immune reaction initially caused by a pathogen can trigger allergies.
- Identify skin rashes and asthma as examples of allergies linked to prior immune reactions.
- Explain how the interaction between pathogens and the immune system can lead to non-communicable conditions.
Health issues
Severe physical ill health can lead to depression and other mental illness.
- Describe how severe physical ill health can increase the risk of depression and other mental illness.
- Explain at least one mechanism linking a named physical illness to a named mental illness.
- Recognise that physical and mental health can affect each other in both directions.
Health issues
Students should be able to describe the relationship between health and disease and the interactions between different types of disease.
- Define health in terms of physical and mental well-being.
- Describe how different types of disease can interact and affect each other.
- Explain examples of interactions, such as a communicable disease worsening a non-communicable disease or a weakened immune system increasing risk.
Health issues
Students should be able to translate disease incidence information between graphical and numerical forms, construct and interpret frequency tables and diagrams, bar charts and histograms, and use a scatter diagram to identify a correlation between two variables.
- Translate disease incidence data between tables, numerical values and graphs.
- Construct and interpret frequency tables, bar charts and histograms for disease data.
- Use a scatter diagram to identify and describe a correlation between two variables.
Health issues
Students should understand the principles of sampling as applied to scientific data, including epidemiological data.
- Define population and sample and explain why a sample is used.
- Describe how random sampling reduces bias and how sample size affects reliability.
- Interpret epidemiological data by discussing representativeness, bias and confounding variables.
Health issues
Viruses living in cells can be the trigger for cancers.
- State that some viruses can trigger cancer by altering genes that control cell division in host cells.
- Describe how a tumour forms when the cell cycle is no longer controlled.
- Apply the idea to a named example, such as HPV and cervical cancer, and recognise that infection is a risk factor rather than a guaranteed cause.
Homeostasis
All control systems include:
- Identify receptors, coordination centres and effectors in a named control system.
- Explain how negative feedback reverses a change to restore an internal set point.
- Apply the general control-system sequence to nervous and hormonal examples.
Homeostasis
blood glucose concentration
- Describe how the pancreas responds to changes in blood glucose concentration using insulin.
- (HT only) Explain how glucagon acts antagonistically to insulin to restore blood glucose concentration.
- Relate blood glucose control to the supply of glucose for respiration and to cell damage at extremes.
Homeostasis
body temperature
- State that body temperature is controlled by homeostasis.
- Explain why maintaining about 37 °C is important for enzyme-controlled reactions.
- Describe the general components of the automatic control system that regulates body temperature.
Homeostasis
cells called receptors, which detect stimuli (changes in the environment)
- State that receptors are cells that detect stimuli.
- Describe a stimulus as a change in the internal or external environment.
- Match named receptors to the stimuli they detect.
Homeostasis
coordination centres (such as the brain, spinal cord and pancreas) that receive and process information from receptors
- State that coordination centres receive and process information from receptors.
- Identify the brain, spinal cord and pancreas as examples of coordination centres.
- Describe how a coordination centre sends instructions to effectors to produce a response.
Homeostasis
effectors, muscles or glands, which bring about responses which restore optimum levels.
- Identify muscles and glands as the two effector types in a named control system.
- Describe how muscle contraction or relaxation produces a corrective response.
- Explain how a glandular secretion restores an optimum level by opposing the original change.
Homeostasis
Homeostasis maintains optimal conditions for enzyme action and all cell functions.
- Describe how temperature and pH affect enzyme activity.
- Explain why maintaining optimum conditions is essential for enzyme action and cell function.
- Link named homeostatic responses to the protection of enzyme-controlled reactions.
Homeostasis
In the human body, these include control of:
- State that homeostasis maintains a stable internal environment.
- Identify blood glucose concentration, body temperature and water and ion balance as factors controlled in the human body.
- Describe the general negative feedback pathway from receptor to effector.
Homeostasis
Students should be able to explain that homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.
- Define homeostasis as regulation of internal conditions within narrow limits.
- Describe the roles of receptors, coordination centres and effectors in a homeostatic response.
- Explain how negative feedback restores optimum conditions after an internal or external change.
Homeostasis
These automatic control systems may involve nervous responses or chemical responses.
- Distinguish nervous from chemical responses in terms of speed, duration and transmission route.
- Sequence the components of a nervous response from stimulus to effector.
- Explain how hormonal responses reach and act on specific target cells.
Homeostasis
water levels.
- State that water levels are controlled by homeostasis.
- Explain that water levels must be maintained to provide optimum conditions for enzyme action and cell functions.
- Describe the general components of the control system (receptors, coordination centres, effectors) involved in homeostasis.
Hormones in human reproduction
(HT only) Students should be able to explain the interactions of FSH, oestrogen, LH and progesterone, in the control of the menstrual cycle.
- Describe the source, target organ, and function of FSH, oestrogen, LH, and progesterone.
- Explain how the four hormones interact in a specific sequence to control the menstrual cycle.
- Apply the concept of negative feedback to explain how progesterone regulates FSH and LH levels.
Hormones in human reproduction
(HT only) Students should be able to extract and interpret data from graphs showing hormone levels during the menstrual cycle.
- Recognise that interpreting interacting hormone graphs is a Higher Tier only requirement.
- Read hormone concentrations and days accurately from a menstrual cycle graph.
- Describe the sequence of FSH, oestrogen, LH and progesterone changes across the 28-day cycle.
- Explain how each hormone peak or trough relates to events such as follicle maturation and ovulation.
Hormones in human reproduction
During puberty reproductive hormones cause secondary sex characteristics to develop.
- State that puberty is caused by reproductive hormones.
- Identify testosterone and oestrogen as the main male and female reproductive hormones, and name their organs of production.
- Describe at least two secondary sex characteristics for each sex and link them to the correct hormone.
Hormones in human reproduction
Follicle stimulating hormone (FSH) causes maturation of an egg in the ovary.
- Identify the pituitary gland as the source of FSH.
- State that the ovary is the target organ for FSH.
- Describe the role of FSH in causing the maturation of an egg in the ovary.
Hormones in human reproduction
Luteinising hormone (LH) stimulates the release of the egg.
- Identify the pituitary gland as the source of LH.
- State that the ovary is the target organ for LH.
- Describe the role of LH in stimulating the release of the egg (ovulation).
Hormones in human reproduction
Oestrogen and progesterone are involved in maintaining the uterus lining.
- State the source and role of oestrogen in rebuilding the uterus lining.
- Describe how progesterone maintains the uterus lining and inhibits FSH and LH.
- Explain how falling progesterone leads to menstruation when fertilisation does not occur.
Hormones in human reproduction
Oestrogen is the main female reproductive hormone produced in the ovary. At puberty eggs begin to mature and one is released approximately every 28 days. This is called ovulation.
- State that oestrogen is the main female reproductive hormone produced in the ovary.
- Describe the process of ovulation, including the approximate 28-day cycle.
- Explain the role of oestrogen in the menstrual cycle and the development of secondary sex characteristics.
Hormones in human reproduction
Several hormones are involved in the menstrual cycle of a woman.
- Name the hormones involved in the menstrual cycle and identify where each is produced.
- Describe the sequence of hormonal events that leads to ovulation and maintenance of the uterus lining.
- Explain how changes in progesterone and FSH lead to menstruation when fertilisation does not occur.
Hormones in human reproduction
Students should be able to describe the roles of hormones in human reproduction, including the menstrual cycle.
- Name the hormones involved in the menstrual cycle and state their sources.
- Describe the sequence of hormonal changes and their effects on the ovary and uterus.
- Describe the role of testosterone in sperm production and relate reproductive hormones to fertility treatments or contraception.
Hormones in human reproduction
Testosterone is the main male reproductive hormone produced by the testes and it stimulates sperm production.
- Identify the testes as the source of testosterone.
- Describe testosterone as the main male reproductive hormone.
- Explain that testosterone stimulates sperm production.
How carbon dioxide decreased
Algae and plants decreased the percentage of carbon dioxide in the atmosphere by photosynthesis.
- State that algae and plants use carbon dioxide during photosynthesis.
- Describe how carbon from carbon dioxide becomes stored in biomass.
- Explain how photosynthesis by algae and plants decreased the percentage of carbon dioxide in the early atmosphere.
How carbon dioxide decreased
Carbon dioxide was also decreased by the formation of sedimentary rocks and fossil fuels that contain carbon.
- Identify sedimentary rocks and fossil fuels as carbon-containing stores.
- Describe how carbonate compounds and buried organic remains remove carbon dioxide from the atmosphere.
- Explain how the formation of sedimentary rocks and fossil fuels decreased atmospheric carbon dioxide.
How carbon dioxide decreased
describe and explain the formation of deposits of limestone, coal, crude oil and natural gas.
- Describe the origin of limestone, coal, crude oil and natural gas.
- Explain how burial, limited oxygen, heat and pressure over millions of years form each deposit.
- Distinguish the source organisms of coal from those of crude oil and natural gas.
How carbon dioxide decreased
describe the main changes in the atmosphere over time and some of the likely causes of these changes
- Describe the main changes in the atmosphere over time, including the decrease in carbon dioxide and increases in oxygen and nitrogen.
- Explain likely causes of these changes, including dissolving in oceans, formation of sedimentary rocks and fossil fuels, photosynthesis, and volcanic activity.
- Use data on atmospheric composition to support descriptions and explanations of change over time.
How materials are cycled
All materials in the living world are recycled to provide the building blocks for future organisms.
- Describe how elements taken in by organisms are returned to the environment by named processes.
- Explain why the recycling of materials is essential for the continued growth of future organisms.
- Apply the idea of material recycling to a named element such as carbon or nitrogen in a food chain.
How materials are cycled
explain the importance of the carbon and water cycles to living organisms.
- Describe the main transfers in the carbon cycle and the water cycle.
- Explain why carbon and water are essential to living organisms.
- Predict how a change in either cycle could affect the survival of organisms.
How materials are cycled
recall that many different materials cycle through the abiotic and biotic components of an ecosystem
- Identify abiotic and biotic components of a named ecosystem.
- Trace a named material through at least two transfers between abiotic and biotic components.
- Explain how decomposers return materials to the abiotic environment.
How materials are cycled
Students should be able to explain the role of microorganisms in cycling materials through an ecosystem by returning carbon to the atmosphere as carbon dioxide and mineral ions to the soil.
- Describe how microorganisms break down dead material and waste.
- Explain how respiration by microorganisms returns carbon dioxide to the atmosphere.
- Explain how decomposition releases mineral ions into the soil for plant uptake.
How materials are cycled
The carbon cycle returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis.
- Describe the processes that return carbon from organisms to the atmosphere as carbon dioxide.
- Explain how plants use atmospheric carbon dioxide in photosynthesis to form organic compounds.
- Interpret a simple carbon cycle diagram to trace the movement of carbon between organisms and the atmosphere.
How materials are cycled
The water cycle provides fresh water for plants and animals on land before draining into the seas. Water is continuously evaporated and precipitated.
- Describe the stages of the water cycle in the correct sequence, including evaporation, condensation, precipitation and drainage.
- Explain how the water cycle supplies fresh water to plants and animals on land.
- Explain why the water cycle is continuous and why it is driven by energy from the Sun.
How oxygen increased
Algae and plants produced the oxygen that is now in the atmosphere by photosynthesis, which can be represented by the equation:
- Write the balanced symbol equation for photosynthesis.
- Describe how algae and plants produced oxygen in the early atmosphere.
- Explain the link between photosynthesis and the increase in atmospheric oxygen.
How oxygen increased
Algae first produced oxygen about 2.7 billion years ago and soon after this oxygen appeared in the atmosphere. Over the next billion years plants evolved and the percentage of oxygen gradually increased to a level that enabled animals to evolve.
- Outline the sequence of events that led to oxygen accumulation in the atmosphere.
- Explain why the increase in oxygen was gradual and took billions of years.
- Relate the rise in atmospheric oxygen to the evolution of animals.
Human activities which contribute to an increase in greenhouse gases in the atmosphere
Based on peer-reviewed evidence, many scientists believe that human activities will cause the temperature of the Earth’s atmosphere to increase at the surface and that this will result in global climate change.
- Describe what peer-reviewed evidence is and why scientists rely on it.
- Explain how human activities can increase surface temperature through greenhouse gases.
- Link rising surface temperature to global climate change using a named consequence.
Human activities which contribute to an increase in greenhouse gases in the atmosphere
carbon dioxide
- Identify human activities that release carbon dioxide into the atmosphere.
- Explain how increased carbon dioxide causes warming through absorption and re-emission of infrared radiation.
- Apply the greenhouse effect to consequences such as climate change.
Human activities which contribute to an increase in greenhouse gases in the atmosphere
describe uncertainties in the evidence base
- Identify and describe sources of uncertainty in climate evidence
- Explain how each source affects confidence in conclusions
- Describe how improved measurements and multiple evidence lines reduce uncertainty
Human activities which contribute to an increase in greenhouse gases in the atmosphere
evaluate the quality of evidence in a report about global climate change given appropriate information
- Judge the reliability of climate data using sample size, timescale and coverage
- Identify bias, selective use of data and conflicts of interest in a report
- Reach and justify an overall judgement about how much confidence the evidence deserves
Human activities which contribute to an increase in greenhouse gases in the atmosphere
However, it is difficult to model such complex systems as global climate change. This leads to simplified models, speculation and opinions presented in the media that may be based on only parts of the evidence and which may be biased.
- Describe why global climate is a complex system that is difficult to model accurately.
- Explain how simplification in models leads to uncertainty and how scientists test model predictions.
- Evaluate a media claim about climate change by identifying the evidence used, evidence omitted and possible bias.
Human activities which contribute to an increase in greenhouse gases in the atmosphere
methane.
- Identify human activities that release methane into the atmosphere.
- Explain how methane contributes to the greenhouse effect through absorption and re-emission of infrared radiation.
- Compare the relative contribution of methane and carbon dioxide to climate change.
Human activities which contribute to an increase in greenhouse gases in the atmosphere
recognise the importance of peer review of results and of communicating results to a wide range of audiences.
- Describe peer review as independent scrutiny of methods, data and conclusions by qualified specialists.
- Explain how communicating results to different audiences supports checking, replication and informed decision-making.
- Evaluate a simple scenario by identifying one strength and one limitation of peer review or of a communication method.
Human activities which contribute to an increase in greenhouse gases in the atmosphere
Some human activities increase the amounts of greenhouse gases in the atmosphere. These include:
- Identify human activities that increase carbon dioxide, methane and other greenhouse gases.
- Describe how combustion, deforestation, agriculture and waste disposal each add greenhouse gases.
- Link each named activity to the specific greenhouse gas it releases.
Human activities which contribute to an increase in greenhouse gases in the atmosphere
Students should be able to recall two human activities that increase the amounts of each of the greenhouse gases carbon dioxide and methane.
- State two human activities that increase carbon dioxide in the atmosphere.
- State two human activities that increase methane in the atmosphere.
- Match each named activity to the correct greenhouse gas, CO₂ or CH₄.
Human defence systems
antibody production
- Describe antibodies as proteins produced by lymphocytes that bind to specific antigens.
- Explain how complementary binding leads to clumping and destruction of pathogens.
- Relate antibody production by memory lymphocytes to immunity against a named disease.
Human defence systems
antitoxin production.
- Describe antitoxins as lymphocyte proteins that neutralise pathogen toxins.
- Explain how neutralising a toxin prevents damage to cells.
- Distinguish antitoxin action from antibody action against pathogens.
Human defence systems
If a pathogen enters the body the immune system tries to destroy the pathogen.
- State that the immune system destroys pathogens that enter the body.
- Describe how phagocytes and lymphocytes destroy pathogens.
- Explain how antibody specificity and memory cells protect against later infection.
Human defence systems
nose
- Describe how hairs and mucus in the nose trap pathogens.
- Explain how cilia and swallowing remove trapped pathogens from the respiratory tract.
- Relate nose defences to reducing infection risk in the lungs.
Human defence systems
phagocytosis
- Define phagocytosis as the engulfing and digestion of pathogens by white blood cells.
- Describe the stages of phagocytosis in the correct order.
- Explain why phagocytosis is described as a non-specific defence.
Human defence systems
skin
- Describe how intact skin prevents pathogens from entering the body.
- Explain how sebum and lysozyme contribute to defence against microorganisms.
- Relate breaks in the skin to increased risk of infection.
Human defence systems
stomach.
- State that the stomach contains hydrochloric acid which kills microorganisms.
- Describe how the stomach contributes to non-specific defence against pathogens.
- Explain how mucus protects the stomach lining and why the acidic environment is important for both defence and enzyme activity.
Human defence systems
Students should be able to describe the non-specific defence systems of the human body against pathogens, including the:
- Identify the main non-specific defence systems of the human body.
- Describe how the skin, nose, trachea, bronchi and stomach defend against pathogens.
- Explain why these defences are described as non-specific.
Human defence systems
Students should be able to explain the role of the immune system in the defence against disease.
- Describe how phagocytes destroy pathogens by phagocytosis.
- Explain how lymphocytes produce antibodies that bind to specific antigens and clump pathogens.
- Explain how memory cells produce a faster, larger response on re-exposure to the same pathogen.
Human defence systems
trachea and bronchi
- Identify the trachea and bronchi and state their role in conducting air to the lungs.
- Describe how cartilage, mucus and cilia in the trachea and bronchi defend against pathogens.
- Explain how damage to cilia, for example by smoking, can increase the risk of respiratory infection.
Human defence systems
White blood cells help to defend against pathogens by:
- State that white blood cells defend the body against pathogens.
- Describe phagocytosis and antibody production as defence mechanisms.
- Explain how these mechanisms reduce the harm caused by pathogens.
Human endocrine system
adrenal gland
- Identify the adrenal glands as endocrine glands above the kidneys on a diagram of the human body.
- Describe the endocrine system as a system of glands that secrete hormones into the bloodstream.
- Locate the adrenal glands in relation to other major endocrine glands on a diagram.
Human endocrine system
ovary
- Identify the ovaries as endocrine glands that secrete oestrogen and progesterone.
- Describe the roles of oestrogen and progesterone in the female body.
- Explain how ovarian hormones travel in the blood to reach target organs.
Human endocrine system
pancreas
- Identify the pancreas on a diagram and state that it secretes insulin into the blood.
- Describe the effects of insulin on blood glucose concentration and glycogen storage.
- (HT only) Explain how negative feedback involving insulin and glucagon controls blood glucose concentration.
Human endocrine system
pituitary gland
- Identify the pituitary gland and state its location in the brain.
- Describe how pituitary hormones are transported and act on target organs.
- Explain the pituitary's role as the master gland in controlling other endocrine glands.
Human endocrine system
Students should be able to describe the principles of hormonal coordination and control by the human endocrine system.
- Identify endocrine glands and state that they secrete hormones directly into the bloodstream.
- Explain how a hormone reaches and affects only its target organ.
- Compare the characteristics of hormonal coordination with nervous coordination.
Human endocrine system
Students should be able to identify the position of the following on a diagram of the human body:
- Identify the position of the pituitary, thyroid, adrenal glands, pancreas, ovaries and testes on a diagram of the human body.
- Relate the position of each gland to its role in the endocrine system.
- Use correct anatomical terms to describe gland locations.
Human endocrine system
testes.
- Identify the testes as endocrine glands that secrete testosterone.
- Describe the roles of testosterone in sperm production and male secondary sexual characteristics.
- Explain how testosterone travels in the blood to reach target organs.
Human endocrine system
The endocrine system is composed of glands which secrete chemicals called hormones directly into the bloodstream. The blood carries the hormone to a target organ where it produces an effect. Compared to the nervous system the effects are slower but act for longer.
- Describe how endocrine glands secrete hormones directly into the bloodstream and how blood carries them to target organs.
- Explain why hormonal effects are slower to begin but longer lasting than nervous effects.
- Apply the gland-hormone-target organ model to a named example such as adrenaline acting on the heart and liver.
Human endocrine system
The pituitary gland in the brain is a ‘master gland’ which secretes several hormones into the blood in response to body conditions. These hormones in turn act on other glands to stimulate other hormones to be released to bring about effects.
- Identify the pituitary gland as the master gland located in the brain.
- Describe how the pituitary secretes hormones into the blood in response to body conditions.
- Explain how pituitary hormones stimulate other glands to release hormones that produce effects.
Human endocrine system
thyroid
- Identify the thyroid on a diagram of the human endocrine system.
- Describe the thyroid’s position at the front of the neck around the upper trachea.
- Distinguish the thyroid from the pituitary, adrenal glands, pancreas, ovaries and testes by location.
Inherited disorders
Cystic fibrosis (a disorder of cell membranes) is caused by a recessive allele.
- State that cystic fibrosis is caused by a recessive allele and affects cell membranes.
- Use genetic diagrams to predict the probability of offspring inheriting cystic fibrosis from carrier parents.
- Distinguish between an affected person (ff) and a carrier (Ff) and explain why carriers do not show symptoms.
Inherited disorders
Polydactyly (having extra fingers or toes) is caused by a dominant allele.
- Describe polydactyly as having extra fingers or toes.
- Explain that polydactyly is caused by a dominant allele.
- Use a genetic diagram to predict the probability of offspring inheriting polydactyly.
Inherited disorders
Some disorders are inherited. These disorders are caused by the inheritance of certain alleles.
- State that inherited disorders are caused by the inheritance of certain alleles.
- Distinguish between dominant and recessive inheritance of disorder alleles.
- Use a genetic diagram to predict the chance of offspring inheriting a disorder allele.
Inherited disorders
Students should make informed judgements about the economic, social and ethical issues concerning embryo screening, given appropriate information.
- Identify economic, social and ethical issues concerning embryo screening from given information.
- Weigh benefits and drawbacks of embryo screening to reach an informed judgement.
- Justify a conclusion about embryo screening using evidence and considering different viewpoints.
Internal energy
Energy is stored inside a system by the particles (atoms and molecules) that make up the system. This is called internal energy.
- Describe internal energy as energy stored by the particles of a system.
- Explain how heating or cooling changes the internal energy of a system.
- Distinguish between internal energy and temperature using particle ideas.
Internal energy
Heating changes the energy stored within the system by increasing the energy of the particles that make up the system. This either raises the temperature of the system or produces a change of state.
- Define internal energy as the total kinetic and potential energy of the particles in a system.
- Explain how heating can either raise temperature or cause a change of state.
- Describe why temperature remains constant during a change of state.
Internal energy
Internal energy is the total kinetic energy and potential energy of all the particles (atoms and molecules) that make up a system.
- State that internal energy is the total kinetic and potential energy of all particles in a system.
- Explain how kinetic and potential energy of particles contribute to internal energy.
- Compare internal energy and temperature for systems with different masses.
Ionic bonding
Students should be able to draw dot and cross diagrams for ionic compounds formed by metals in Groups 1 and 2 with non-metals in Groups 6 and 7.
- Draw dot and cross diagrams for compounds formed from Group 1 or 2 metals and Group 6 or 7 non-metals.
- Use dots and crosses to show which atom supplied each transferred electron.
- Show the resulting ions with full outer shells and correct charges.
Ionic bonding
Students should be able to work out the charge on the ions of metals and non-metals from the group number of the element, limited to the metals in Groups 1 and 2, and non-metals in Groups 6 and 7.
- State the charge on ions formed by Group 1, Group 2, Group 6 and Group 7 elements.
- Explain how the group number determines the number of electrons lost or gained.
- Write correct ion symbols with superscript charges for these elements.
Ionic bonding
The charge on the ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 relates to the group number of the element in the periodic table.
- State the charge on ions formed by elements in Groups 1, 2, 6 and 7.
- Explain how the group number relates to the charge on the ion formed.
- Predict the charge on an ion from the element's position in the periodic table.
Ionic bonding
The electron transfer during the formation of an ionic compound can be represented by a dot and cross diagram, eg for sodium chloride
- Draw a dot and cross diagram to show the electron transfer in sodium chloride.
- Represent the ions formed in an ionic compound with correct charges and electron arrangements.
- Interpret a dot and cross diagram to identify the electron transfer and the resulting ions.
Ionic bonding
When a metal atom reacts with a non-metal atom electrons in the outer shell of the metal atom are transferred. Metal atoms lose electrons to become positively charged ions. Non-metal atoms gain electrons to become negatively charged ions. The ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 have the electronic structure of a noble gas (Group 0).
- Describe how electrons are transferred when a metal atom reacts with a non-metal atom.
- Explain how metal atoms form positive ions and non-metal atoms form negative ions.
- Deduce the charge on ions formed by elements in Groups 1, 2, 6 and 7 and relate this to noble gas electronic structures.
Ionic compounds
An ionic compound is a giant structure of ions. Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions. These forces act in all directions in the lattice and this is called ionic bonding.
- Describe an ionic compound as a giant structure of ions.
- Explain that ionic bonding involves strong electrostatic forces of attraction between oppositely charged ions acting in all directions in the lattice.
- Relate the giant ionic lattice to observable properties such as high melting and boiling points.
Ionic compounds
deduce that a compound is ionic from a diagram of its structure in one of the specified forms
- Identify ions and their charges from a dot and cross, ball and stick or three-dimensional diagram.
- Explain how the regular repeating arrangement of ions shows a giant ionic structure.
- Compare an ionic diagram with a covalent diagram and justify which type of bonding is shown.
Ionic compounds
describe the limitations of using dot and cross, ball and stick, two and three-dimensional diagrams to represent a giant ionic structure
- Describe at least three limitations of common diagrams used to represent giant ionic structures.
- Explain why each limitation matters for understanding the real lattice.
- Evaluate which type of diagram best represents a giant ionic structure and justify the choice.
Ionic compounds
Students should be familiar with the structure of sodium chloride but do not need to know the structures of other ionic compounds.
- Describe the arrangement of ions in a sodium chloride lattice, including 6:6 coordination.
- Explain how strong electrostatic forces lead to the high melting point of sodium chloride.
- Apply general ionic bonding ideas to unfamiliar ionic compounds without recalling their specific structures.
Ionic compounds
The structure of sodium chloride can be represented in the following forms:
- Draw and interpret a dot-and-cross diagram showing the formation of Na⁺ and Cl⁻ ions from sodium and chlorine atoms.
- Describe the giant ionic lattice of sodium chloride, including the 1:1 ratio and the six-fold coordination of each ion.
- Explain how the lattice structure and strong electrostatic attractions account for the high melting point of sodium chloride.
Ionic compounds
work out the empirical formula of an ionic compound from a given model or diagram that shows the ions in the structure.
- Count each type of ion shown in a diagram of an ionic structure.
- Simplify an ion ratio to its simplest whole-number form.
- Write the empirical formula of an ionic compound with the cation first and correct subscripts.
Key ideas
atoms bond by either transferring electrons from one atom to another or by sharing electrons
- State that atoms bond by transferring electrons or by sharing electrons.
- Describe, using a suitable example, how a metal and a non-metal form ions by electron transfer.
- Explain, using a suitable example, how non-metal atoms share electron pairs to complete their outer shells.
Key ideas
chemical reactions take place in only three different ways:
- Explain chemical reactions in terms of proton transfer, electron transfer, and electron sharing.
- Identify the type of subatomic particle interaction occurring in given examples of chemical reactions.
- Relate macroscopic chemical changes to fundamental interactions between protons and electrons.
Key ideas
electron sharing
- Draw dot-and-cross diagrams for simple covalent molecules, showing shared pairs of electrons.
- Explain how a shared pair of electrons holds two non-metal atoms together.
- Identify the number of shared pairs and lone pairs in a given simple molecule.
Key ideas
electron transfer
- Define oxidation and reduction in terms of electron transfer.
- Write balanced half-equations for oxidation and reduction.
- Identify the oxidising agent and reducing agent in a redox reaction.
Key ideas
elements show periodic relationships in their chemical and physical properties
- Describe how elements are arranged in the periodic table and how this produces periodic relationships.
- Identify and compare trends in physical and chemical properties within groups and across periods.
- Use named elements and observations to justify a stated periodic trend.
Key ideas
energy is conserved in chemical reactions so can therefore be neither created or destroyed.
- State that energy is conserved in chemical reactions and is neither created nor destroyed.
- Classify reactions as exothermic or endothermic from temperature changes.
- Interpret reaction profiles to show energy changes.
Key ideas
evolution occurs by a process of natural selection and accounts both for biodiversity and how organisms are all related to varying degrees.
- Describe the process of natural selection, including variation, competition, survival and reproduction.
- Explain how natural selection can lead to evolution, new species and biodiversity.
- Explain that all organisms are related to varying degrees through common ancestry.
Key ideas
life on Earth is dependent on photosynthesis in which green plants and algae trap light from the Sun to fix carbon dioxide and combine it with hydrogen from water to make organic compounds and oxygen
- Describe the reactants, products and energy transfer in photosynthesis.
- Explain how plants and algae differ in obtaining carbon dioxide and water.
- Explain why life on Earth depends on photosynthesis for food and oxygen.
Key ideas
life processes depend on molecules whose structure is related to their function
- Describe how the structure of an enzyme relates to its role as a biological catalyst.
- Explain how the structure of DNA allows it to store and copy genetic information.
- Relate the structure of named biological molecules to the functions they perform in organisms.
Key ideas
living organisms are interdependent and show adaptations to their environment
- Describe how organisms in a community depend on each other for food, shelter and other resources.
- Explain how a named adaptation gives an organism an advantage in its habitat.
- Interpret food webs and predator-prey graphs to predict the effect of a change in one population.
Key ideas
living organisms may form populations of single species, communities of many species and ecosystems, interacting with each other, with the environment and with humans in many different ways
- Define population, community and ecosystem accurately.
- Describe ways in which organisms interact with each other, with the environment and with humans.
- Explain how interactions within an ecosystem can affect the organisms that live there.
Key ideas
matter is composed of tiny particles called atoms and there are about 100 different naturally occurring types of atoms called elements
- Define atom and element using the particle model.
- Use atomic number to identify an element and distinguish it from its isotopes.
- Classify given substances as elements, compounds or mixtures from formulae or diagrams.
Key ideas
organic compounds are used as fuels in cellular respiration to allow the other chemical reactions necessary for life
- State the word equation (and balanced symbol equation for Higher Tier) for aerobic respiration and identify the products of anaerobic respiration in animals and in plant or yeast cells.
- Explain how the energy released from organic compounds is transferred and used to drive other chemical reactions necessary for life.
- Compare aerobic and anaerobic respiration in terms of oxygen requirement, products and relative energy released per glucose molecule.
Key ideas
proton transfer
- Define an acid as a proton donor and a base as a proton acceptor.
- Explain neutralisation as the transfer of protons to form water.
- Write the ionic equation for neutralisation.
Key ideas
that differences, for example between pressures or temperatures or electrical potentials, are the drivers of change
- Identify the difference in pressure, temperature or electrical potential that drives a given change.
- Describe the direction of change produced by a stated difference.
- Relate the size of a difference to the rate of change and recognise the zero-difference case.
Key ideas
that physical laws and models are expressed in mathematical form.
- State a physical law as an equation linking measurable quantities.
- Describe the simplifying assumptions in a given physical model.
- Substitute values into an equation, rearrange it and give the answer with the correct unit.
Key ideas
that proportionality, for example between weight and mass of an object or between force and extension in a spring, is an important aspect of many models in science
- State the equations linking weight to mass and force to extension, and identify the constant in each.
- Use proportionality to predict values and calculate a constant from data.
- Interpret graphs to decide whether a proportional model applies, including the limit of proportionality.
Key ideas
the characteristics of a living organism are influenced by its genome and its interaction with the environment
- Describe the genome as the entire genetic material of an organism and state that genes code for proteins.
- Explain how both genetic and environmental factors can influence the characteristics of a living organism.
- Apply the idea of genetic and environmental influence to unfamiliar examples, including data from twin or plant studies.
Key ideas
the chemicals in ecosystems are continually cycling through the natural world
- Describe how carbon and other chemicals cycle through the biotic and abiotic components of an ecosystem.
- Explain the role of decomposers in breaking down dead material and returning mineral ions and carbon compounds to the environment.
- Interpret diagrams of the carbon cycle and explain how photosynthesis, respiration, feeding, decomposition and combustion move carbon between stores.
Key ideas
the concept of cause and effect in explaining such links as those between force and acceleration, or between changes in atomic nuclei and radioactive emissions
- State the cause and the effect in a given force-and-acceleration situation.
- Describe how a change in an atomic nucleus leads to emission of alpha, beta or gamma radiation.
- Justify whether a stated link is causal by referring to a mechanism and to evidence.
Key ideas
the fundamental units of living organisms are cells, which may be part of highly adapted structures including tissues, organs and organ systems, enabling living processes to be performed effectively
- State that cells are the fundamental units of living organisms.
- Describe the hierarchy of cells, tissues, organs and organ systems using named examples.
- Explain how specialisation and organisation allow living processes to be carried out effectively.
Key ideas
the phenomena of ‘action at a distance’ and the related concept of the field as the key to analysing electrical, magnetic and gravitational effects
- Describe what is meant by action at a distance and give examples from gravity, electricity and magnetism.
- Interpret field lines to state the direction and relative strength of a field.
- Use the field model to explain a named non-contact effect in terms of what creates the field and what experiences the force.
Key ideas
the shapes of molecules (groups of atoms bonded together) and the way giant structures are arranged is of great importance in terms of the way they behave
- Describe how the shape and arrangement of simple molecules affect their properties.
- Relate the arrangement of particles in giant covalent, metallic and ionic structures to their physical properties.
- Compare simple molecular and giant structures, using structural differences to explain observed behaviour.
Key ideas
the use of models, as in the particle model of matter or the wave models of light and of sound
- Describe how a named model represents a physical situation.
- Use a model to explain an observation or predict an outcome.
- Evaluate the limitations of a model for a given phenomenon.
Key ideas
there are barriers to reaction so reactions occur at different rates
- Describe the activation energy barrier as the minimum energy needed for a successful collision.
- Explain how the size of the barrier affects the rate of a reaction.
- Apply collision theory to predict how changing temperature, concentration, surface area or adding a catalyst affects rate.
Key ideas
these periodic properties can be explained in terms of the atomic structure of the elements
- Relate an element's group and period to its electron configuration.
- Explain periodic trends in reactivity using nuclear charge, shell distance and shielding.
- Use electron configurations to account for similarities within a group and differences between groups.
Land use
Humans reduce the amount of land available for other animals and plants by building, quarrying, farming and dumping waste.
- State four human activities that reduce land available to other organisms.
- Describe how each activity removes or damages habitat.
- Explain how reduced habitat area leads to lower biodiversity.
Land use
The decay or burning of the peat releases carbon dioxide into the atmosphere.
- Describe how carbon stored in peat is returned to the atmosphere by decay or burning.
- Explain why draining or extracting peat increases the rate of carbon dioxide release.
- Apply the carbon store and transfer idea to evaluate the atmospheric effect of peatland land use.
Land use
The destruction of peat bogs, and other areas of peat to produce garden compost, reduces the area of this habitat and thus the variety of different plant, animal and microorganism species that live there (biodiversity).
- Describe what a peat bog is and why it supports distinctive species.
- Explain how peat extraction for compost reduces habitat area and biodiversity.
- Relate peat bog destruction to the loss of plant, animal and microorganism species.
Levels of organisation
A range of experimental methods using transects and quadrats are used by ecologists to determine the distribution and abundance of species in an ecosystem.
- Describe how quadrats and transects are used to sample species in a habitat.
- Explain how random sampling and repeat measurements improve the reliability of abundance estimates.
- Interpret quadrat and transect data to compare the distribution and abundance of species.
Levels of organisation
calculate arithmetic means
- Calculate the arithmetic mean of a set of values accurately.
- Calculate a mean from a frequency table using value × frequency.
- Interpret a calculated mean in the context of the practical data, including its unit.
Levels of organisation
Consumers that kill and eat other animals are predators, and those eaten are prey. In a stable community the numbers of predators and prey rise and fall in cycles.
- Define predator and prey and identify each in a given food web.
- Describe how predator and prey populations rise and fall in repeating cycles.
- Explain why the predator population changes after the prey population changes.
Levels of organisation
Feeding relationships within a community can be represented by food chains. All food chains begin with a producer which synthesises molecules. This is usually a green plant or alga which makes glucose by photosynthesis.
- Describe how food chains represent feeding relationships and the direction of energy transfer within a community.
- Identify the producer in a food chain and explain that it synthesises molecules, usually by photosynthesis in green plants or algae.
- Construct and interpret food chains using correct arrow direction, starting with a producer.
Levels of organisation
In relation to abundance of organisms students should be able to:
- Calculate the mean, median, and mode for a set of data on organism abundance.
- Select appropriate scales and plot data on the abundance of organisms accurately.
- Interpret graphs showing the distribution and abundance of organisms.
Levels of organisation
plot and draw appropriate graphs selecting appropriate scales for the axes.
- Select suitable scales for both axes so that plotted data occupy most of the grid.
- Plot data points accurately and label axes with quantity and unit.
- Draw an appropriate line or curve of best fit that represents the trend in the data.
Levels of organisation
Producers are eaten by primary consumers, which in turn may be eaten by secondary consumers and then tertiary consumers.
- Define producer, primary consumer, secondary consumer and tertiary consumer.
- Construct or interpret a food chain using correct arrow direction.
- Explain how the same organism can occupy different trophic levels in different food chains.
Levels of organisation
Required practical activity 7: measure the population size of a common species in a habitat. Use sampling techniques to investigate the effect of a factor on the distribution of this species.
- Describe how to use a quadrat to sample a common species and estimate its population size.
- Explain how a transect can be used to investigate the effect of a factor on the distribution of a species.
- Evaluate sampling methods and suggest improvements to increase reliability and reduce bias.
Levels of organisation
Students should be able to interpret graphs used to model these cycles.
- Read and label the axes and key on a predator-prey graph.
- Describe the pattern of peaks and troughs shown by two population lines.
- Explain how the graph shows the predator population responding to changes in the prey population.
Levels of organisation
Students should understand that photosynthetic organisms are the producers of biomass for life on Earth.
- Define a producer as a photosynthetic organism that synthesises organic molecules from inorganic raw materials.
- Describe how glucose made in photosynthesis is used to build biological molecules that make up biomass.
- Explain why producers are the starting point for biomass and energy transfer in food chains and webs.
Levels of organisation
understand the terms mean, mode and median
- Define the terms mean, mode and median accurately.
- Identify the mode and median of a given data set, including cases with no mode or two modes.
- Select and justify an appropriate measure of central tendency for a described context.
Life cycle assessment
disposal at the end of its useful life, including transport and distribution at each stage.
- Describe ways in which products can be disposed of at the end of their useful life.
- Explain why transport and distribution are counted at each stage of a life cycle assessment.
- Compare the environmental impact of different disposal routes for a named product.
Life cycle assessment
extracting and processing raw materials
- Describe how raw materials are extracted from the Earth and processed into usable forms.
- Explain environmental and resource impacts arising from extraction and processing.
- Apply the idea of a functional unit when comparing the impacts of different materials.
Life cycle assessment
Life cycle assessments (LCAs) are carried out to assess the environmental impact of products in each of these stages:
- List and describe the stages of a life cycle assessment, including processing and packaging.
- Explain how transport and distribution are considered at each stage of an LCA.
- Use LCA data to compare products and justify a conclusion about environmental impact.
Life cycle assessment
manufacturing and packaging
- Describe the manufacturing and packaging stages of a product life cycle.
- Explain how packaging material choices affect environmental impact across the life cycle.
- Compare packaging options fairly using a stated functional unit.
Life cycle assessment
Selective or abbreviated LCAs can be devised to evaluate a product but these can be misused to reach pre-determined conclusions, eg in support of claims for advertising purposes.
- Describe what is meant by a selective or abbreviated LCA.
- Explain how the choice of stages or impacts can lead to a pre-determined conclusion.
- Evaluate an advertising claim by identifying what an abbreviated LCA has included and omitted.
Life cycle assessment
Students should be able to carry out simple comparative LCAs for shopping bags made from plastic and paper.
- Carry out a simple comparative LCA for plastic and paper shopping bags, covering extraction, manufacture, use and disposal.
- Explain how reuse and disposal choices change the overall environmental impact of each bag.
- Reach and justify a conclusion that weighs evidence from all four LCA stages and states the assumptions made.
Life cycle assessment
use and operation during its lifetime
- State what happens during the use and operation stage of a product's life cycle.
- Give examples of resources consumed and wastes produced while a product is used.
- Compare the use stage of two products in terms of their environmental impact.
Life cycle assessment
Use of water, resources, energy sources and production of some wastes can be fairly easily quantified. Allocating numerical values to pollutant effects is less straightforward and requires value judgements, so LCA is not a purely objective process.
- State at least three inputs or outputs of a product life cycle that can be fairly easily quantified.
- Explain why allocating numerical values to pollutant effects requires value judgements.
- Conclude, with a product example, why an LCA is not a purely objective process.
Limiting reactants (HT only)
In a chemical reaction involving two reactants, it is common to use an excess of one of the reactants to ensure that all of the other reactant is used. The reactant that is completely used up is called the limiting reactant because it limits the amount of products.
- Define limiting reactant and excess reactant using the idea of complete consumption.
- Use a balanced equation to identify which reactant is limiting from given mole amounts.
- Explain why the limiting reactant determines the maximum amount of product formed.
Limiting reactants (HT only)
Students should be able to explain the effect of a limiting quantity of a reactant on the amount of products it is possible to obtain in terms of amounts in moles or masses in grams.
- Calculate the maximum product in moles from a limiting reactant using the balanced equation ratio.
- Convert the maximum product from moles to mass in grams using relative formula mass.
- Explain why the limiting reactant fixes the amount of product and why excess reactant does not increase it.
Magnetic fields
A magnetic compass contains a small bar magnet. The Earth has a magnetic field. The compass needle points in the direction of the Earth’s magnetic field.
- Describe the structure of a magnetic compass and how it responds to a magnetic field.
- Explain why a compass needle points in the direction of the Earth's magnetic field.
- Predict and explain the effect of a nearby magnet on a compass needle.
Magnetic fields
describe how to plot the magnetic field pattern of a magnet using a compass
- Describe the steps needed to plot a magnetic field pattern with a compass.
- Explain why the compass is moved to each marked point in turn.
- Describe how to add direction arrows to a plotted field pattern.
Magnetic fields
draw the magnetic field pattern of a bar magnet showing how strength and direction change from one point to another
- Draw the magnetic field pattern around a bar magnet, including direction arrows.
- Use line spacing to represent how field strength changes from point to point.
- Explain how a plotting compass can be used to determine field direction at a chosen point.
Magnetic fields
explain how the behaviour of a magnetic compass is related to evidence that the core of the Earth must be magnetic.
- Describe how a magnetic compass behaves in the Earth's magnetic field.
- Use compass behaviour as evidence that the Earth has a magnetic field originating in its core.
- Distinguish between geographic and magnetic poles when explaining compass direction.
Magnetic fields
The direction of the magnetic field at any point is given by the direction of the force that would act on another north pole placed at that point. The direction of a magnetic field line is from the north (seeking) pole of a magnet to the south(seeking) pole of the magnet.
- Define the direction of a magnetic field at a point using the force on a north pole.
- Draw and interpret magnetic field lines around a bar magnet with correct arrow directions.
- Use field-line spacing to compare magnetic field strength at different points.
Magnetic fields
The force between a magnet and a magnetic material is always one of attraction.
- Identify iron, steel, cobalt and nickel as magnetic materials.
- Explain why a magnet always attracts a magnetic material.
- Distinguish between the behaviour of a magnetic material and that of a second permanent magnet.
Magnetic fields
The region around a magnet where a force acts on another magnet or on a magnetic material (iron, steel, cobalt and nickel) is called the magnetic field.
- Define the magnetic field as the region where a magnetic force can act.
- Identify iron, steel, cobalt and nickel as magnetic materials.
- Describe how field lines and a plotting compass represent the direction and relative strength of a magnetic field.
Magnetic fields
The strength of the magnetic field depends on the distance from the magnet. The field is strongest at the poles of the magnet.
- Describe how magnetic field strength changes with distance from a magnet.
- Identify the poles as the strongest parts of the magnetic field.
- Use field-line spacing and a plotting compass to compare field strength at different points.
Mains electricity
earth wire – green and yellow stripes.
- Identify the earth wire from its green and yellow striped insulation.
- Describe how the earth wire and a fuse or circuit breaker protect a user during a fault.
- Explain why double-insulated appliances do not need an earth connection.
Mains electricity
live wire – brown
- Identify the live wire as the brown-insulated conductor.
- Describe the path of the live wire through a three-pin plug.
- Explain why the live wire presents a shock hazard.
Mains electricity
Most electrical appliances are connected to the mains using three- core cable.
- Identify the live, neutral and earth wires in a three-core cable and state the function of each.
- Explain how the earth wire and a fuse or circuit breaker protect a user when a fault occurs.
- Recognise that double-insulated appliances do not require an earth connection.
Mains electricity
neutral wire – blue
- Identify the neutral wire from its blue insulation.
- Describe the role of the neutral wire in completing a mains circuit.
- Explain why correct identification of the neutral conductor matters for safe wiring.
Mains electricity
Students should be able to explain:
- Link each named mains component to a stated safety consequence.
- Describe the role of the live, neutral and earth wires in a mains circuit.
- Explain how a fuse and earthing together protect a user during a fault.
Mains electricity
that a live wire may be dangerous even when a switch in the mains circuit is open
- Explain why an open switch does not make the live wire safe to touch.
- Describe how a current can pass through a person who touches a live wire.
- Justify placing a switch in the live wire rather than the neutral wire.
Mains electricity
the dangers of providing any connection between the live wire and earth.
- Describe how a connection between the live wire and earth can cause a large current to flow.
- Explain how that current can harm a person or cause a fire.
- Explain how earthing, fuses, circuit breakers or double insulation reduce the danger.
Mains electricity
The insulation covering each wire is colour coded for easy identification:
- State that the insulation on each mains wire is colour coded.
- Match each insulation colour to the correct wire name (live is brown, neutral is blue, earth is green and yellow stripes).
- Explain how colour coding helps to identify wires safely.
Mains electricity
The live wire carries the alternating potential difference from the supply. The neutral wire completes the circuit. The earth wire is a safety wire to stop the appliance becoming live.
- Identify the live, neutral and earth wires in a three-core mains cable and state the colour of each.
- Describe the function of the live wire, the neutral wire and the earth wire in an appliance circuit.
- Explain how the earth wire and a fuse or circuit breaker protect a user when a fault makes a metal case live.
Mains electricity
The potential difference between the live wire and earth (0 V) is about 230 V. The neutral wire is at, or close to, earth potential (0 V). The earth wire is at 0 V, it only carries a current if there is a fault.
- State the approximate potential difference between the live wire and earth and the potential difference of the neutral and earth wires.
- Explain why the neutral wire is at or close to earth potential while still carrying current in a working circuit.
- Describe the condition under which the earth wire carries a current and relate this to electrical safety.
Maintaining biodiversity
breeding programmes for endangered species
- Describe how a breeding programme for an endangered species is carried out.
- Explain how breeding programmes help maintain biodiversity.
- Evaluate the conditions needed for a breeding programme to succeed.
Maintaining biodiversity
protection and regeneration of rare habitats
- State what is meant by a rare habitat and give one example.
- Distinguish protection from regeneration and describe one method of each.
- Explain how protecting or regenerating a rare habitat can increase biodiversity.
Maintaining biodiversity
recycling resources rather than dumping waste in landfill.
- Describe how recycling reduces waste sent to landfill and conserves raw materials.
- Explain how recycling can lower energy use, carbon dioxide emissions and pollution.
- Evaluate the benefits and limitations of recycling compared with dumping waste in landfill.
Maintaining biodiversity
reduction of deforestation and carbon dioxide emissions by some governments
- Describe how deforestation affects atmospheric carbon dioxide concentrations.
- Explain how reducing deforestation can lower carbon dioxide emissions and protect biodiversity.
- Evaluate ways in which governments can reduce deforestation and carbon dioxide emissions.
Maintaining biodiversity
reintroduction of field margins and hedgerows in agricultural areas where farmers grow only one type of crop
- Define monoculture and explain why it reduces biodiversity.
- Describe how field margins and hedgerows provide habitat and corridors for wildlife.
- Explain how reintroducing these features can increase biodiversity in arable farmland.
Maintaining biodiversity
Scientists and concerned citizens have put in place programmes to reduce the negative effects of humans on ecosystems and biodiversity.
- Describe a programme that reduces human negative effects on ecosystems and biodiversity.
- Explain how scientists and concerned citizens contribute to such a programme.
- Explain how monitoring data can show whether a conservation programme is reducing harm.
Maintaining biodiversity
Students should be able to describe both positive and negative human interactions in an ecosystem and explain their impact on biodiversity.
- Describe one positive and one negative human interaction with an ecosystem.
- Explain how a named interaction changes biodiversity through habitat and niche availability.
- Apply the terms biodiversity, habitat, species and population accurately to a familiar example.
Maintaining biodiversity
These include:
- State what biodiversity means and why maintaining it is important.
- Identify several named strategies used to maintain biodiversity.
- Explain how a chosen strategy increases or protects biodiversity.
Mass changes when a reactant or product is a gas
Some reactions may appear to involve a change in mass but this can usually be explained because a reactant or product is a gas and its mass has not been taken into account. For example: when a metal reacts with oxygen the mass of the oxide produced is greater than the mass of the metal or in thermal decompositions of metal carbonates carbon dioxide is produced and escapes into the atmosphere leaving the metal oxide as the only solid product.
- Describe how the measured mass can increase when a metal reacts with oxygen in an open system.
- Describe how the measured mass can decrease when a metal carbonate thermally decomposes in an open system.
- Use a balanced symbol equation to identify the gas responsible for an observed mass change.
Mass changes when a reactant or product is a gas
Students should be able to explain any observed changes in mass in non-enclosed systems during a chemical reaction given the balanced symbol equation for the reaction and explain these changes in terms of the particle model.
- Interpret a balanced symbol equation to identify gaseous reactants and products.
- Explain an observed mass change in a non-enclosed system using the particle model.
- Predict whether the measured mass will increase or decrease for a given reaction and justify the prediction.
Mass number, atomic number and isotopes
All atoms of a particular element have the same number of protons. The number of protons in an atom of an element is called its atomic number.
- Define atomic number as the number of protons in an atom.
- Explain why all atoms of an element have the same atomic number.
- Use atomic number to identify an element and distinguish it from its isotopes.
Mass number, atomic number and isotopes
Atoms can be represented as shown in this example:
- Interpret nuclide notation to identify the number of protons and neutrons in an atom.
- Write nuclide notation correctly for a given atom or isotope.
- Explain how isotopes of the same element differ in mass number but not atomic number.
Mass number, atomic number and isotopes
Atoms of the same element can have different numbers of neutrons; these atoms are called isotopes of that element.
- Define isotopes as atoms of the same element with different numbers of neutrons.
- Determine the number of protons, neutrons and electrons in a given isotope from its notation.
- Explain why isotopes of an element have the same chemical properties but can differ in physical properties.
Mass number, atomic number and isotopes
Atoms turn into positive ions if they lose one or more outer electron(s).
- Describe how a neutral atom becomes a positive ion by losing one or more outer electrons.
- Determine the charge of a positive ion from its proton and electron counts.
- Write the symbol of a positive ion with the charge shown as a superscript.
Mass number, atomic number and isotopes
In an atom the number of electrons is equal to the number of protons in the nucleus. Atoms have no overall electrical charge.
- State the relative charges of protons and electrons.
- Explain why an atom has no overall electrical charge.
- Identify whether a given particle is a neutral atom or an ion from its proton and electron numbers.
Mass number, atomic number and isotopes
Students should be able to relate differences between isotopes to differences in conventional representations of their identities, charges and masses.
- Identify the number of protons, neutrons and electrons in a given isotope or ion from its conventional representation.
- Explain how differences in neutron number lead to different mass numbers for isotopes of the same element.
- Interpret and write conventional representations that show element identity, mass number and charge for atoms and ions.
Mass number, atomic number and isotopes
The total number of protons and neutrons in an atom is called its mass number.
- State that mass number is the total number of protons and neutrons in an atom.
- Calculate the number of neutrons in an atom from its mass number and atomic number.
- Represent a nuclide using the correct notation with mass number as a superscript and atomic number as a subscript.
Meiosis
all gametes are genetically different from each other.
- Describe how meiosis produces gametes with half the normal chromosome number.
- Explain how the random distribution of chromosomes leads to genetic variation in gametes.
- Apply the concept of genetic variation in gametes to examples such as human sperm and egg cells.
Meiosis
Cells in reproductive organs divide by meiosis to form gametes.
- Identify the reproductive organs where meiosis takes place.
- State that cells in reproductive organs divide by meiosis to form gametes.
- Recognise examples of gametes in animals and plants.
Meiosis
copies of the genetic information are made
- State that genetic information is copied before meiosis.
- Describe the structure of a replicated chromosome as having two identical copies of DNA.
- Explain why copying is necessary for four gametes to each receive a single set of chromosomes.
Meiosis
Gametes join at fertilisation to restore the normal number of chromosomes. The new cell divides by mitosis. The number of cells increases. As the embryo develops cells differentiate.
- Describe how fertilisation restores the normal chromosome number in the zygote.
- Explain how mitosis increases the number of cells during embryo development.
- Describe how cells differentiate as the embryo develops to become specialised.
Meiosis
Students should be able to explain how meiosis halves the number of chromosomes in gametes and fertilisation restores the full number of chromosomes.
- Describe how meiosis halves the chromosome number to form haploid gametes.
- Explain how fertilisation restores the diploid chromosome number in the zygote.
- Relate haploid and diploid numbers to human cells and explain why chromosome number stays constant across generations.
Meiosis
the cell divides twice to form four gametes, each with a single set of chromosomes
- Describe that a cell divides twice during meiosis to form four gametes.
- State that each gamete contains a single set of chromosomes.
- Explain that all gametes produced by meiosis are genetically different.
Meiosis
When a cell divides to form gametes:
- State that copies of genetic information are made before cell division in meiosis.
- Describe how the cell divides twice to form four gametes with a single set of chromosomes.
- Explain that all gametes produced by meiosis are genetically different.
Metabolism
All of these aspects are covered in more detail in the relevant specification section but are linked together here.
- Identify the separate processes that are linked in the metabolism topic.
- Construct a flow diagram connecting digestion, the liver, the blood and the kidneys.
- Explain how one metabolic process affects another using a named example.
Metabolism
breakdown of excess proteins to form urea for excretion.
- State that excess amino acids are broken down in the liver to form urea.
- Describe the route of urea from the liver to excretion in urine.
- Explain why urea must be excreted and how this links to kidney function.
Metabolism
conversion of glucose to starch, glycogen and cellulose
- State that glucose is converted into starch, glycogen and cellulose.
- Describe each conversion as a condensation reaction that releases water.
- Relate the properties of starch, glycogen and cellulose to their functions in plants and animals.
Metabolism
Metabolism includes:
- Identify examples of synthesis reactions included in metabolism.
- Identify examples of breakdown reactions included in metabolism.
- Describe metabolism as the sum of enzyme controlled reactions in a cell or body.
Metabolism
Metabolism is the sum of all the reactions in a cell or the body.
- State that metabolism is the sum of all reactions in a cell or the body.
- Give examples of synthesis and breakdown reactions that contribute to metabolism.
- Explain that respiration is part of metabolism because it supplies energy for other reactions.
Metabolism
respiration
- Describe the process of aerobic respiration and its products.
- Compare aerobic and anaerobic respiration in terms of oxygen requirement and energy release.
- Explain how the energy released by respiration is used in cells.
Metabolism
Students should be able to explain the importance of sugars, amino acids, fatty acids and glycerol in the synthesis and breakdown of carbohydrates, proteins and lipids.
- Identify sugars, amino acids, fatty acids and glycerol as the small molecules used to synthesise carbohydrates, proteins and lipids.
- Describe synthesis as condensation and breakdown as hydrolysis for carbohydrates, proteins and lipids.
- Apply the roles of these molecules to examples such as glycogen formation or protein synthesis.
Metabolism
The energy transferred by respiration in cells is used by the organism for the continual enzyme controlled processes of metabolism that synthesise new molecules.
- State that energy transferred by respiration is used for metabolism.
- Describe metabolism as the sum of enzyme controlled reactions that synthesise new molecules.
- Explain why metabolic synthesis is continual in a living organism.
Metabolism
the formation of lipid molecules from a molecule of glycerol and three molecules of fatty acids
- State the reactants and products when a lipid is formed from glycerol and fatty acids.
- Describe lipid formation as a condensation reaction that releases water and forms ester bonds.
- Relate the structure of lipids to their functions in organisms.
Metabolism
the use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins
- State that glucose and nitrate ions are used to form amino acids.
- Describe how amino acids are joined to synthesise proteins.
- Explain the effect of nitrate ion deficiency on protein synthesis and plant growth.
Metal oxides
Metals react with oxygen to produce metal oxides. The reactions are oxidation reactions because the metals gain oxygen.
- Describe the reaction of a metal with oxygen to produce a metal oxide.
- Explain why the reaction of a metal with oxygen is an oxidation reaction in terms of the metal gaining oxygen.
- Write word equations and balanced symbol equations for the formation of metal oxides.
Metal oxides
Students should be able to explain reduction and oxidation in terms of loss or gain of oxygen.
- Define oxidation as gain of oxygen and reduction as loss of oxygen.
- Identify which reactant is oxidised and which is reduced in a given metal–oxygen reaction.
- Use a balanced equation to justify an explanation of oxidation and reduction in terms of oxygen.
Metallic bonding
Metals consist of giant structures of atoms arranged in a regular pattern.
- Describe the giant regular structure of a metal.
- Explain the role of delocalised electrons in metallic bonding.
- Link the structure of a metal to at least one of its physical properties.
Metallic bonding
The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure. The sharing of delocalised electrons gives rise to strong metallic bonds. The bonding in metals may be represented in the following form:
- Describe the arrangement of positive metal ions and delocalised electrons in a giant metallic structure.
- Explain how the sharing of delocalised electrons gives rise to strong metallic bonds.
- Relate the mobility of delocalised electrons to the electrical and thermal conductivity of metals.
Metals and non-metals
Elements that do not form positive ions are non-metals.
- State that elements which do not form positive ions are non-metals.
- Describe how metals form positive ions by losing electrons and how non-metals form negative ions by gaining electrons.
- Classify an element as a metal or non-metal using its ion formation and position in the periodic table.
Metals and non-metals
Elements that react to form positive ions are metals.
- State that metals are elements that react to form positive ions.
- Describe electron loss from a metal atom using a named example and its ion symbol.
- Classify an element as a metal or non-metal from its position in the periodic table or the charge on its ion.
Metals and non-metals
explain how the atomic structure of metals and non-metals relates to their position in the periodic table
- Identify the group and period of an element from its electron configuration.
- Explain how the number of outer electrons determines whether an element behaves as a metal or a non-metal.
- Relate the atomic structure of Group 0 elements to their position and unreactive nature.
Metals and non-metals
explain how the reactions of elements are related to the arrangement of electrons in their atoms and hence to their atomic number.
- Describe how the outer-shell electron arrangement of an element determines whether it gains, loses or shares electrons.
- Explain how atomic number determines electron arrangement and therefore the position of an element in the periodic table.
- Relate the reactions of elements in the same group to their similar outer-shell electron arrangements.
Metals and non-metals
explain the differences between metals and non-metals on the basis of their characteristic physical and chemical properties. This links to Group 0 (page 74), Group 1 (page 74), Group 7 (page 75) and Bonding, structure and the properties of matter (page 75)
- Explain the physical differences between metals and non-metals using structure and bonding.
- Explain how electron loss or gain relates to the chemical properties of metals and non-metals.
- Use examples from Groups 0, 1 and 7 to illustrate differences in reactivity.
Metals and non-metals
The majority of elements are metals. Metals are found to the left and towards the bottom of the periodic table. Non-metals are found towards the right and top of the periodic table.
- Label the metal and non-metal regions on a blank periodic table.
- Classify given elements as metals or non-metals using their position.
- Explain how the stepped line separates metals from non-metals.
Metals as conductors
Metals are good conductors of electricity because the delocalised electrons in the metal carry electrical charge through the metal. Metals are good conductors of thermal energy because energy is transferred by the delocalised electrons.
- Describe the structure of a metal in terms of positive ions and delocalised electrons.
- Explain how delocalised electrons enable metals to conduct electricity.
- Explain how delocalised electrons enable metals to conduct thermal energy.
Microscopy
An electron microscope has much higher magnification and resolving power than a light microscope. This means that it can be used to study cells in much finer detail. This has enabled biologists to see and understand many more sub-cellular structures.
- Define magnification and resolving power and distinguish between them.
- Explain why an electron microscope has greater resolving power than a light microscope, referring to wavelength.
- Describe how electron microscopy has increased understanding of sub-cellular structures, using named examples.
Microscopy
explain how electron microscopy has increased understanding of sub-cellular structures.
- Describe how the wavelength of the radiation used limits the resolution of a microscope.
- Explain how the shorter wavelength of electrons allows smaller sub-cellular structures to be resolved and studied.
- Apply the ideas of magnification and resolution to a named organelle to show how electron microscopy increased understanding.
Microscopy
magnification = size of image size of real object
- State and rearrange the relationship magnification = image size ÷ real size.
- Calculate magnification, image size or real size from given measurements after converting units.
- Use a scale bar on a micrograph to determine magnification or real size.
Microscopy
Students should be able to carry out calculations involving magnification, real size and image size using the formula:
- State and rearrange the equation magnification = image size ÷ real size.
- Carry out calculations of magnification, image size and real size with consistent units.
- Interpret calculated sizes in the context of cells and sub-cellular structures.
Microscopy
Students should be able to express answers in standard form if appropriate.
- Convert numbers between ordinary form and standard form using A × 10ⁿ.
- Use standard form correctly when recording or calculating cell sizes and magnifications.
- Check that a standard form answer has a coefficient between 1 and 10 and an appropriate index.
Microscopy
understand how microscopy techniques have developed over time
- Describe how light microscopes and electron microscopes differ in the radiation used, magnification and resolution.
- Explain how the TEM and SEM produce different views of a specimen.
- Link improvements in microscopy to the discovery of new biological structures.
Mitosis and the cell cycle
Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome.
- Describe the events of interphase, including cell growth and DNA replication.
- Explain why ribosomes and mitochondria must increase in number before mitosis.
- State that DNA replication produces two identical copies of each chromosome without changing the chromosome number.
Mitosis and the cell cycle
Cell division by mitosis is important in the growth and development of multicellular organisms.
- State that mitosis produces two genetically identical diploid daughter cells from one parent cell.
- Explain how mitosis contributes to growth by increasing cell number in multicellular organisms.
- Describe how mitosis supports development by producing cells that form tissues and organs.
- Identify named locations, such as root tips and shoot tips, where mitosis occurs for growth.
Mitosis and the cell cycle
Cells divide in a series of stages called the cell cycle. Students should be able to describe the stages of the cell cycle, including mitosis.
- State the three main stages of the cell cycle in the correct order.
- Describe the key events of cell growth and DNA replication.
- Explain how mitosis produces two genetically identical daughter cells.
Mitosis and the cell cycle
During the cell cycle the genetic material is doubled and then divided into two identical cells.
- Describe how genetic material is doubled during interphase.
- Explain how mitosis divides the genetic material into two identical cells.
- State that the daughter cells have the same chromosome number as the parent cell.
Mitosis and the cell cycle
Finally the cytoplasm and cell membranes divide to form two identical cells.
- Describe the final stage of the cell cycle in which the cytoplasm and cell membranes divide.
- Explain why the two daughter cells formed are genetically identical to each other and to the parent cell.
- Relate the outcome of the cell cycle to growth, repair or asexual reproduction in a named organism.
Mitosis and the cell cycle
In mitosis one set of chromosomes is pulled to each end of the cell and the nucleus divides.
- Describe how one set of chromosomes is pulled to each end of the cell during mitosis.
- Explain that mitosis results in the formation of two genetically identical nuclei.
- Relate mitosis to growth, repair and asexual reproduction in multicellular organisms.
Mitosis and the cell cycle
Students need to understand the three overall stages of the cell cycle but do not need to know the different phases of the mitosis stage.
- Outline the three overall stages of the cell cycle in the correct order.
- Explain the importance of DNA replication before nuclear division.
- Describe the outcome of the cell cycle as two genetically identical daughter cells without naming individual phases of mitosis.
Mitosis and the cell cycle
Students should be able to recognise and describe situations in given contexts where mitosis is occurring.
- Identify situations involving growth, repair or replacement as contexts where mitosis occurs.
- Describe what is happening in a given context using the outcome of mitosis, including genetically identical diploid daughter cells.
- Distinguish between contexts involving mitosis and contexts involving meiosis, such as gamete formation.
Mixtures
A mixture consists of two or more elements or compounds not chemically combined together. The chemical properties of each substance in the mixture are unchanged.
- Define a mixture as two or more elements or compounds not chemically combined.
- Explain why each substance in a mixture keeps its chemical properties.
- Select a suitable physical separation method for a given mixture.
Mixtures
describe, explain and give examples of the specified processes of separation
- Describe the apparatus and steps for filtration, crystallisation, simple distillation, fractional distillation and chromatography.
- Explain each separation in terms of a physical property such as solubility, boiling point or state.
- Give a suitable named example of a mixture separated by each specified process.
Mixtures
Mixtures can be separated by physical processes such as filtration, crystallisation, simple distillation, fractional distillation and chromatography. These physical processes do not involve chemical reactions and no new substances are made.
- Identify filtration, crystallisation, simple distillation, fractional distillation and chromatography as physical separation processes.
- Describe how each named process separates a given mixture, referring to a property such as solubility or boiling point.
- Explain why these separation processes are physical and do not produce new substances.
Mixtures
suggest suitable separation and purification techniques for mixtures when given appropriate information.
- Choose a suitable separation technique from information about solubility, state and boiling point.
- Explain why the chosen technique works for the mixture described.
- Describe how purity can be assessed using melting point or boiling point data.
Moles (HT only)
Chemical amounts are measured in moles. The symbol for the unit mole is mol.
- State that chemical amounts are measured in moles and that the unit symbol is mol.
- Describe one mole as containing 6.02 × 10²³ particles.
- Use mole ratios from a balanced equation to compare amounts of reactants and products.
Moles (HT only)
One mole of a substance contains the same number of the stated particles, atoms, molecules or ions as one mole of any other substance.
- State that one mole of any substance contains the same number of stated particles.
- Identify the particle type, atom, molecule or ion, in a given amount of substance.
- Convert between mass, moles and number of particles using molar mass and the Avogadro constant.
Moles (HT only)
Students should be able to use the relative formula mass of a substance to calculate the number of moles in a given mass of that substance and vice versa.
- Calculate the relative formula mass of a substance from its formula.
- Convert a given mass of a substance into an amount in moles.
- Convert a given amount in moles of a substance into its mass in grams.
Moles (HT only)
Students should understand that the measurement of amounts in moles can apply to atoms, molecules, ions, electrons, formulae and equations, for example that in one mole of carbon (C) the number of atoms is the same as the number of molecules in one mole of carbon dioxide (CO₂).
- State the number of entities in one mole of a specified substance.
- Identify the entity being counted in a given chemical context.
- Use a balanced equation to determine mole ratios between substances.
Moles (HT only)
The mass of one mole of a substance in grams is numerically equal to its relative formula mass.
- Calculate the relative formula mass of a substance from its formula and relative atomic masses.
- State that the mass of one mole in grams is numerically equal to the relative formula mass.
- Convert between mass in grams and amount in moles using molar mass.
Moles (HT only)
The number of atoms, molecules or ions in a mole of a given substance is the Avogadro constant. The value of the Avogadro constant is 6.02 x 10²³ per mole.
- State the value of the Avogadro constant as 6.02 × 10²³ per mole.
- Calculate the number of particles in a given number of moles.
- Calculate the number of moles from a given number of particles.
Momentum is a property of moving objects
mass, m, in kilograms, kg
- Identify m as the mass term in the momentum relationship.
- Convert a stated mass to kilograms before calculating momentum.
- Substitute mass in kilograms into p = mv with the correct unit.
Momentum is a property of moving objects
momentum = mass × velocity
- Recall and use the equation momentum = mass × velocity to calculate momentum in kg m/s.
- Convert mass to kilograms and velocity to metres per second before substituting into p = m v.
- Describe momentum as a vector quantity and interpret positive and negative values in one-dimensional motion.
Momentum is a property of moving objects
Momentum is defined by the equation:
- State and use the equation p = mv to calculate the momentum of a moving object (HT only).
- Explain why momentum is a vector and how direction affects its value (HT only).
- Compare the momentum of different objects based on their mass and velocity (HT only).
Momentum is a property of moving objects
momentum, p, in kilograms metre per second, kg m/s
- Identify p as the symbol for momentum.
- State kilograms metre per second (kg m/s) as the unit of momentum.
- Calculate momentum and report the result with the correct kg m/s unit.
Momentum is a property of moving objects
p = m v
- Use the equation p = mv to calculate momentum, mass or velocity when the other two quantities are known (HT only).
- Apply correct units kg, m/s and kg m/s consistently in calculations (HT only).
- Interpret momentum as a vector and use signs to represent direction in one-dimensional problems (HT only).
Momentum is a property of moving objects
velocity, v, in metres per second, m/s
- Identify v as the velocity term in the momentum relationship.
- Use metres per second (m/s) as the unit of velocity.
- Apply a signed velocity consistently when calculating momentum in one dimension.
National and global energy resources
A renewable energy resource is one that is being (or can be) replenished as it is used.
- Define a renewable energy resource in terms of replenishment as it is used.
- Classify named energy resources as renewable or non-renewable and justify each choice.
- Explain why a renewable resource can still be unreliable even though it is replenished.
National and global energy resources
compare ways that different energy resources are used, the uses to include transport, electricity generation and heating
- Describe how transport, electricity generation and heating each use different energy resources.
- Compare two or more resources for a given use by weighing advantages against drawbacks.
- Justify a resource choice for a specified use using criteria such as portability, reliability and environmental impact.
National and global energy resources
consider the environmental issues that may arise from the use of different energy resources
- Describe at least three environmental issues arising from different energy resources.
- Classify given environmental issues as local, national or global in scale.
- Compare two energy resources by weighing their environmental impacts in a structured table.
National and global energy resources
describe the environmental impact arising from the use of different energy resources
- Identify the main pollutant or waste produced by named energy resources.
- Explain how a named impact arises, linking the resource to its environmental effect.
- Compare the environmental impacts of two resources across their life cycles.
National and global energy resources
describe the main energy sources available
- Name the main energy sources used nationally and globally.
- Classify each named source as renewable or non-renewable.
- Describe how named sources are used to generate electricity or provide transport energy.
National and global energy resources
distinguish between energy resources that are renewable and energy resources that are non-renewable
- Define renewable and non-renewable energy resources using the idea of replenishment rate.
- Classify a range of named energy resources as renewable or non-renewable with a reason for each.
- Apply the distinction to a real energy supply context and justify the classification given.
National and global energy resources
explain patterns and trends in the use of energy resources. WS 3.5
- Interpret a graph or table to identify a trend in energy resource use.
- Explain a trend by linking it to at least one cause such as cost, policy or technology.
- Compare patterns in energy use between different resources or countries using data.
National and global energy resources
show that science has the ability to identify environmental issues arising from the use of energy resources but not always the power to deal with the issues because of political, social, ethical or economic considerations.
- Explain how scientific evidence identifies environmental issues from energy use.
- Describe political, social, ethical and economic factors that can prevent action on those issues.
- Apply the science-versus-society idea to a named energy resource in a written argument.
National and global energy resources
The main energy resources available for use on Earth include: fossil fuels (coal, oil and gas), nuclear fuel, bio-fuel, wind, hydro- electricity, geothermal, the tides, the Sun and water waves.
- Name the main energy resources available on Earth and classify each as renewable or non-renewable.
- Describe the energy transfer involved for a named energy resource.
- Compare energy resources using at least two criteria such as reliability, cost or environmental impact.
National and global energy resources
The uses of energy resources include: transport, electricity generation and heating.
- State the three main uses of energy resources: transport, electricity generation and heating.
- Match named energy resources to appropriate uses and explain the match.
- Evaluate the suitability of a resource for a particular use using given information.
National and global energy resources
understand why some energy resources are more reliable than others
- Define reliability as the ability to supply energy whenever demand arises.
- Compare named energy resources and explain how far their output can be controlled or predicted.
- Justify a judgement about which of two resources is more reliable using evidence about supply conditions.
Neutralisation of acids and salt production
Acids are neutralised by alkalis (eg soluble metal hydroxides) and bases (eg insoluble metal hydroxides and metal oxides) to produce salts and water, and by metal carbonates to produce salts, water and carbon dioxide.
- State the products of reactions between acids and alkalis or bases, and between acids and metal carbonates.
- Classify substances as alkalis, bases or metal carbonates and predict the salt formed in each reaction.
- Write word equations and balanced symbol equations, including state symbols, for neutralisation reactions.
Neutralisation of acids and salt production
predict products from given reactants
- Classify given reactants as acids, metal oxides, metal hydroxides, carbonates or ammonia.
- Predict the salt, water and any carbon dioxide formed from a stated acid-base or acid-carbonate reaction, noting ammonia forms only a salt.
- Construct word and balanced symbol equations for the predicted products using correct formulae and state symbols.
Neutralisation of acids and salt production
the acid used (hydrochloric acid produces chlorides, nitric acid produces nitrates, sulfuric acid produces sulfates)
- Identify the negative ion supplied by hydrochloric, nitric and sulfuric acids.
- Construct the correct salt name from a named acid and a named base, alkali or carbonate.
- Apply the naming rule accurately to salts containing variable-charge positive ions.
Neutralisation of acids and salt production
The particular salt produced in any reaction between an acid and a base or alkali depends on:
- Identify the anion contributed by a given acid and the metal or ammonium ion contributed by a given base or alkali.
- Name the salt produced from a specified acid and base or alkali, including salts of variable-charge metals.
- Write correct formulae for salts by balancing the charges on the cation and anion.
Neutralisation of acids and salt production
the positive ions in the base, alkali or carbonate.
- Identify the positive ion in a given base, alkali or carbonate.
- Use the positive ion to name the salt formed when it reacts with a named acid.
- Deduce the formula of a salt by balancing the charges of its positive and negative ions.
Neutralisation of acids and salt production
use the formulae of common ions to deduce the formulae of salts.
- State the formulae and charges of common cations and anions accurately.
- Combine a named cation and anion to produce a correctly balanced salt formula.
- Apply brackets correctly when a polyatomic ion appears more than once in a formula.
Newton's First Law
(HT only) The tendency of objects to continue in their state of rest or of uniform motion is called inertia.
- Define inertia in terms of an object’s state of rest or uniform motion.
- Explain how mass affects inertia and the resultant force needed to change motion.
- Apply the concept of inertia to everyday situations involving sudden changes in motion.
Newton's First Law
If the resultant force acting on an object is zero and:
- Describe the motion of a stationary object when the resultant force is zero.
- Describe the motion of a moving object when the resultant force is zero.
- Explain why a non-zero resultant force is needed to change an object’s motion.
Newton's First Law
Newton’s First Law:
- State Newton’s First Law in terms of resultant force and motion.
- Describe the motion of stationary and moving objects when the resultant force is zero.
- Apply Newton’s First Law to explain a familiar situation involving balanced forces.
Newton's First Law
So, the velocity (speed and/or direction) of an object will only change if a resultant force is acting on the object.
- Define velocity as speed in a given direction.
- Explain that a resultant force is required to change an object's speed or direction.
- Apply Newton's First Law to examples including acceleration, braking and turning.
Newton's First Law
So, when a vehicle travels at a steady speed the resistive forces balance the driving force.
- Describe the forces acting on a vehicle travelling at steady speed.
- Explain why the resultant force is zero when speed is constant.
- Calculate an unknown driving or resistive force given that the vehicle travels at steady speed.
Newton's First Law
Students should be able to apply Newton’s First Law to explain the motion of objects moving with a uniform velocity and objects where the speed and/or direction changes.
- Identify when the resultant force on an object is zero from a description of its motion.
- Explain how a non-zero resultant force changes an object’s speed, direction or both.
- Apply Newton’s First Law to unfamiliar examples involving uniform velocity or changing motion.
Newton's First Law
the object is moving, the object continues to move at the same speed and in the same direction. So the object continues to move at the same velocity.
- State that a moving object continues at the same speed and in the same direction when the resultant force is zero.
- Explain that constant speed in a straight line means constant velocity.
- Apply Newton's First Law to a moving object using balanced forces in a named example.
Newton's First Law
the object is stationary, the object remains stationary
- State that a stationary object remains stationary when the resultant force on it is zero.
- Identify balanced forces acting on a stationary object in a given example.
- Explain that zero resultant force means no change in velocity, so a stationary object stays at rest.
Newton's Second Law
acceleration, a, in metres per second squared, m/s²
- State that acceleration is measured in m/s² and define it as the rate of change of velocity.
- Calculate acceleration using a = F ÷ m with force in newtons and mass in kilograms.
- Explain how acceleration changes when resultant force or mass is altered.
Newton's Second Law
As an equation:
- State the word and symbol equations linking resultant force, mass and acceleration.
- Use the equation F = m × a to calculate resultant force, mass or acceleration.
- Apply correct SI units and convert values where necessary before substitution.
Newton's Second Law
F = m a
- State the equation F = m a and identify what each symbol represents, with its unit.
- Rearrange F = m a to find force, mass or acceleration and substitute values correctly.
- Apply the equation to a described situation and interpret the result in terms of the motion.
Newton's Second Law
force, F, in newtons, N
- Define force and state that it is measured in newtons, N.
- Explain the meaning of the newton in terms of mass and acceleration.
- Determine the resultant force on an object from the forces acting along the line of motion.
Newton's Second Law
inertial mass is a measure of how difficult it is to change the velocity of an object
- Define inertial mass as a measure of resistance to a change in velocity.
- Explain how inertial mass affects acceleration for a given resultant force.
- Use F = m a to calculate or compare inertial mass, force and acceleration.
Newton's Second Law
inertial mass is defined as the ratio of force over acceleration.
- State the definition of inertial mass as the ratio of force over acceleration.
- Apply m = F ÷ a to calculate mass, force or acceleration from given data.
- Explain how inertial mass affects the acceleration produced by a resultant force.
Newton's Second Law
mass, m, in kilograms, kg
- State that mass is measured in kilograms and identify the symbol m.
- Convert masses between grams and kilograms accurately before calculation.
- Apply m = F ÷ a to calculate mass from resultant force and acceleration.
Newton's Second Law
Newton’s Second Law:
- Describe how acceleration depends on resultant force and mass.
- Apply F = m × a to calculate force, mass or acceleration.
- Use correct units and convert mass to kilograms before substitution.
Newton's Second Law
Required practical activity 19: investigate the effect of varying the force on the acceleration of an object of constant mass, and the effect of varying the mass of an object on the acceleration produced by a constant force.
- Plan and carry out a practical to measure how acceleration depends on force at constant mass and on mass at constant force.
- Plot and interpret graphs of acceleration against force and acceleration against 1 ÷ mass to identify direct and inverse proportionality.
- Evaluate the method by identifying sources of error and suggesting realistic improvements.
Newton's Second Law
resultant force = mass × acceleration
- Use the word equation resultant force = mass × acceleration to perform calculations.
- Describe the relationship between resultant force, mass and acceleration.
- Rearrange the equation to find mass or acceleration and apply correct units.
Newton's Second Law
Students should be able to estimate the speed, accelerations and forces involved in large accelerations for everyday road transport.
- Estimate realistic speeds, accelerations and forces for everyday road transport.
- Calculate acceleration from a speed change and time, and force from mass and acceleration.
- Justify estimated values using sensible assumptions and appropriate units.
Newton's Second Law
Students should recognise and be able to use the symbol that indicates an approximate value or approximate answer, ̴
- State that ̴ means 'is approximately equal to' and identify it in a written expression.
- Select correctly between = and ̴ when writing the result of a calculation or a measurement.
- Write a rounded or estimated value from a Newton's Second Law calculation using ̴ in the correct position.
Newton's Second Law
The acceleration of an object is proportional to the resultant force acting on the object, and inversely proportional to the mass of the object.
- Explain the proportional and inverse proportional relationships in Newton’s Second Law.
- Use a = F ÷ m to solve numerical problems involving resultant force, mass and acceleration.
- Interpret changes in resultant force or mass and predict the effect on acceleration.
Newton's Third Law
Newton’s Third Law:
- State that when two objects interact, the forces they exert on each other are equal in size and opposite in direction.
- Identify the two objects in an interaction and name the force each exerts on the other.
- Explain why a pair of Newton’s Third Law forces does not cancel out when considering the motion of one object.
Newton's Third Law
Students should be able to apply Newton’s Third Law to examples of equilibrium situations.
- Identify the two interacting objects and the paired forces in a simple equilibrium situation.
- Explain why equal and opposite Third Law forces do not cancel because they act on different objects.
- Use the idea of zero resultant force to describe why an object in equilibrium stays at rest or moves at constant velocity.
Newton's Third Law
Whenever two objects interact, the forces they exert on each other are equal and opposite.
- State Newton’s Third Law for two interacting objects.
- Describe a named interaction using a correctly identified pair of equal and opposite forces.
- Distinguish between a Newton’s Third Law force pair and a pair of balanced forces acting on one object.
Nuclear equations
and a beta particle by the symbol:
- Write the symbol for a beta particle as ⁰₋₁e or ⁰₋₁β in a nuclear equation.
- Explain why the mass number of a beta particle is 0 and its atomic number is −1.
- Balance a nuclear equation for beta decay by conserving mass number and atomic number.
Nuclear equations
In a nuclear equation an alpha particle may be represented by the symbol:
- State the symbol used to represent an alpha particle in a nuclear equation.
- Explain the meaning of the mass number and atomic number in the symbol ⁴₂He or ⁴₂α.
- Use the alpha particle symbol correctly when writing a balanced nuclear equation for alpha decay.
Nuclear equations
Nuclear equations are used to represent radioactive decay.
- Write a balanced nuclear equation for a given alpha or beta decay.
- Identify the daughter nuclide produced when a named parent nuclide undergoes alpha or beta decay.
- Check that mass numbers and atomic numbers are conserved on both sides of a nuclear equation.
Nuclear equations
So alpha decay causes both the mass and charge of the nucleus to decrease.
- State that an alpha particle is a helium nucleus with mass number 4 and charge 2⁺.
- Explain why alpha decay decreases the mass number by 4 and the proton number by 2.
- Balance a nuclear equation for alpha decay using mass numbers and proton numbers.
Nuclear equations
So beta decay does not cause the mass of the nucleus to change but does cause the charge of the nucleus to increase.
- State that beta decay converts a neutron into a proton and an electron.
- Explain why beta decay leaves the mass number unchanged but increases the proton number by 1.
- Balance a nuclear equation for beta decay using mass numbers and proton numbers.
Nuclear equations
Students should be able to use the names and symbols of common nuclei and particles to write balanced equations that show single alpha (α) and beta (β) decay. This is limited to balancing the atomic numbers and mass numbers. The identification of daughter elements from such decays is not required.
- Use standard symbols to represent common nuclei, alpha particles and beta particles in nuclear equations.
- Write balanced equations for single alpha and beta decay by conserving mass number and atomic number.
- Deduce the missing nucleus in a decay equation without needing to identify the daughter element by name.
Nuclear equations
The emission of a gamma ray does not cause the mass or the charge of the nucleus to change.
- Describe gamma emission as the loss of energy from an excited nucleus without loss of particles.
- Write and balance nuclear equations for gamma emission, keeping mass number and atomic number unchanged.
- Distinguish gamma emission from alpha and beta emission in terms of changes to the nucleus.
Nuclear equations
The emission of the different types of nuclear radiation may cause a change in the mass and /or the charge of the nucleus. For example:
- Describe how alpha, beta and gamma emission each affect the mass number and atomic number of a nucleus.
- Write and balance nuclear equations for alpha and beta decay.
- Use conservation of mass number and atomic number to identify the products of a nuclear change.
Osmosis
calculate percentage gain and loss of mass of plant tissue.
- Calculate percentage gain or loss of mass from original and final masses of plant tissue.
- Interpret positive and negative mass changes in terms of water movement into or out of cells.
- Apply the percentage change method accurately to experimental osmosis data.
Osmosis
Required practical activity 2: investigate the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue.
- Carry out the practical safely to obtain valid measurements of mass change in plant tissue.
- Calculate and compare changes in mass across a range of salt or sugar concentrations.
- Explain the results in terms of water movement by osmosis and identify the approximate isotonic concentration.
Osmosis
Students should be able to plot, draw and interpret appropriate graphs.
- Plot a graph of change in mass against concentration with correctly labelled axes and a suitable scale.
- Draw an appropriate line or curve of best fit through plotted points.
- Interpret the graph to identify the isotonic point and describe how mass change varies with concentration.
Osmosis
use percentages
- Calculate a percentage change in mass using the original mass as the denominator.
- Distinguish between percentage gain and percentage loss when interpreting osmosis data.
- Apply percentage calculations to compare results from plant tissue experiments.
Osmosis
use simple compound measures of rate of water uptake
- Calculate rate of water uptake from change in mass or volume and time, using correct compound units.
- Compare rates of water uptake between different concentrations and relate differences to concentration gradients.
- Interpret tabulated or graphical osmosis data to determine change in mass, time and rate.
Osmosis
Water may move across cell membranes via osmosis. Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.
- Define osmosis as the diffusion of water through a partially permeable membrane.
- Explain how water moves from a dilute solution to a concentrated solution.
- Describe the effects of osmosis on plant and animal cells.
Oxidation and reduction in terms of electrons (HT only)
identify in a given reaction, symbol equation or half equation which species are oxidised and which are reduced.
- Define oxidation and reduction in terms of electron loss and gain.
- Determine which species is oxidised and which is reduced from a given symbol equation or half equation.
- Apply changes in ionic charge to justify the identification of oxidised and reduced species.
Oxidation and reduction in terms of electrons (HT only)
Oxidation is the loss of electrons and reduction is the gain of electrons.
- Define oxidation and reduction in terms of electron loss and gain.
- Identify which species is oxidised or reduced in a given ionic equation.
- Write and interpret half-equations showing electron transfer.
Oxidation and reduction in terms of electrons (HT only)
write ionic equations for displacement reactions
- Convert a full displacement equation into an ionic equation by removing spectator ions.
- Balance ionic equations for atoms and charge.
- Explain why spectator ions are omitted from ionic equations.
Particle motion in gases
Changing the temperature of a gas, held at constant volume, changes the pressure exerted by the gas.
- Describe how heating or cooling a gas at constant volume changes the pressure it exerts.
- Explain the pressure change in terms of particle speed, collision frequency and collision force.
- Apply the direct proportionality between pressure and absolute temperature to a fixed mass of gas at constant volume.
Particle motion in gases
explain how the motion of the molecules in a gas is related to both its temperature and its pressure
- Describe how gas molecules move and how their motion produces pressure on the container walls.
- Explain that temperature measures the average kinetic energy of gas molecules and that heating increases their average speed.
- Link increased molecular speed at constant volume to more frequent, more forceful wall collisions and therefore higher pressure.
Particle motion in gases
explain qualitatively the relation between the temperature of a gas and its pressure at constant volume.
- State qualitatively how the pressure of a fixed mass of gas at constant volume changes when its temperature changes.
- Explain the change in pressure in terms of molecular speed, collision frequency and force on the container walls.
- Apply the qualitative relationship to everyday contexts such as a sealed container being heated or cooled.
Particle motion in gases
The molecules of a gas are in constant random motion. The temperature of the gas is related to the average kinetic energy of the molecules.
- Describe the random motion and elastic collisions of gas molecules.
- Explain how temperature is related to the average kinetic energy of gas molecules.
- Use kinetic theory to explain how heating a fixed volume of gas increases its pressure.
Photosynthetic reaction
carbon dioxide + water
- State the word equation for photosynthesis, naming carbon dioxide and water as reactants.
- Explain how light energy absorbed by chlorophyll is transferred to chemical stores in glucose.
- Link the reactants and products to the balanced symbol equation 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.
Photosynthetic reaction
light glucose + oxygen
- Identify light, glucose and oxygen in the photosynthesis equation.
- Explain why light is shown above the arrow rather than as a reactant.
- Describe the fate of glucose and oxygen produced in photosynthesis.
Photosynthetic reaction
Photosynthesis is represented by the equation:
- Write the word equation for photosynthesis.
- Write and balance the symbol equation for photosynthesis.
- Describe the role of light energy and chlorophyll in the reaction.
Photosynthetic reaction
Students should be able to describe photosynthesis as an endothermic reaction in which energy is transferred from the environment to the chloroplasts by light.
- Describe photosynthesis as an endothermic reaction using the correct word and balanced symbol equation.
- Explain that light energy is transferred from the environment to the chloroplasts by light absorbed by chlorophyll.
- Compare photosynthesis with respiration in terms of the direction of energy transfer.
Photosynthetic reaction
Students should recognise the chemical symbols: CO₂, H₂O, O₂ and C₆H₁₂O₆.
- Name the substances represented by CO₂, H₂O, O₂ and C₆H₁₂O₆.
- Use these formulas correctly in the balanced photosynthesis equation.
- Count atoms from subscripts and coefficients to confirm the equation balances.
Plant organ system
extract and interpret information from graphs, charts and tables.
- Read and quote accurate values from graphs, charts and tables, including units.
- Describe trends and compare data sets using evidence from the resource.
- Explain patterns by linking them to relevant biological processes such as transpiration.
Plant organ system
Phloem is composed of tubes of elongated cells. Cell sap can move from one phloem cell to the next through pores in the end walls.
- Describe phloem as tubes of elongated cells with pores in their end walls.
- State that cell sap moves from one phloem cell to the next through the pores.
- Relate the structure of phloem to the transport of dissolved sugars around a plant.
Plant organ system
Phloem tissue transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage. The movement of food molecules through phloem tissue is called translocation.
- State that phloem transports dissolved sugars and define translocation.
- Identify sources and sinks in a given plant transport example.
- Distinguish phloem from xylem in terms of tissue, cargo and direction of movement.
Plant organ system
plot and draw appropriate graphs, selecting appropriate scales for axes
- Select an appropriate scale for each axis so that data fills the grid.
- Label axes correctly with quantity and unit and plot points accurately.
- Draw a suitable line or curve of best fit to represent the trend in the data.
Plant organ system
Root hair cells are adapted for the efficient uptake of water by osmosis, and mineral ions by active transport.
- Describe how the shape of a root hair cell increases the surface area for uptake.
- Explain why water enters root hair cells by osmosis.
- Explain why mineral ions are taken up by active transport and why this requires energy from respiration.
Plant organ system
Students should be able to describe the process of transpiration and translocation, including the structure and function of the stomata.
- Describe the process of transpiration and the role of stomata in water loss.
- Describe translocation as the movement of sugars through the phloem from source to sink.
- Explain how the structure of stomata and guard cells relates to their function in gas exchange and water control.
Plant organ system
Students should be able to explain how the structure of root hair cells, xylem and phloem are adapted to their functions.
- Describe how root hair cells are adapted for absorbing water and mineral ions.
- Explain how xylem structure allows efficient water transport and support.
- Explain how phloem structure allows translocation of dissolved sugars.
Plant organ system
Students should be able to explain the effect of changing temperature, humidity, air movement and light intensity on the rate of transpiration.
- State the direction in which temperature, humidity, air movement and light intensity each change the rate of transpiration.
- Link each factor to the water vapour concentration gradient or to stomatal opening.
- Apply the factors to unfamiliar data, such as a graph of transpiration rate against time or humidity.
Plant organ system
Students should be able to understand and use simple compound measures such as the rate of transpiration.
- Calculate the rate of transpiration from a volume of water lost and a time taken.
- Use the correct compound unit for a rate of transpiration.
- Interpret and compare rates from experimental data or a graph.
Plant organ system
The role of stomata and guard cells are to control gas exchange and water loss.
- Identify stomata and guard cells in a leaf diagram or micrograph.
- Explain how turgid and flaccid guard cells open and close a stoma.
- Relate stomatal opening to gas exchange for photosynthesis and to transpiration.
Plant organ system
The roots, stem and leaves form a plant organ system for transport of substances around the plant.
- Name the roots, stem and leaves as parts of a plant organ system.
- Describe the role of each organ in the transport of water, mineral ions and sugars.
- Explain how the organs work together to move substances around the plant.
Plant organ system
translate information between graphical and numerical form
- Read numerical values accurately from graphs of plant transport data.
- Plot tabulated data correctly with labelled axes and appropriate scales.
- Describe the relationship between environmental factors and transpiration rate using data.
Plant organ system
Xylem tissue transports water and mineral ions from the roots to the stems and leaves. It is composed of hollow tubes strengthened by lignin adapted for the transport of water in the transpiration stream.
- Describe the role of xylem in transporting water and mineral ions from roots to leaves.
- Relate the hollow structure and lignin strengthening of xylem to its function.
- Explain how the transpiration stream moves water through xylem.
Plant tissues
epidermal tissues
- Describe the structure and location of epidermal tissue in leaves, stems and roots.
- Explain how the waxy cuticle, stomata and guard cells control water loss and gas exchange.
- Relate root hair cells to the absorption function of root epidermal tissue.
Plant tissues
meristem tissue found at the growing tips of shoots and roots.
- State where meristem tissue is found in a plant.
- Describe the role of meristem tissue in plant growth.
- Explain how cells produced by meristems become specialised plant tissues.
Plant tissues
palisade mesophyll
- Identify palisade mesophyll in a diagram or micrograph of a leaf section.
- Describe how the features of palisade cells adapt them for photosynthesis.
- Explain how the position and arrangement of palisade mesophyll affect light absorption and gas exchange.
Plant tissues
Plant tissues include:
- Identify the main plant tissues, including epidermal, palisade mesophyll, spongy mesophyll, xylem, phloem and meristem.
- Describe the function of each named plant tissue.
- Explain how the structure of a named plant tissue is adapted to its function.
Plant tissues
spongy mesophyll
- Identify spongy mesophyll in a diagram or micrograph of a leaf section.
- Describe how air spaces in spongy mesophyll allow carbon dioxide and oxygen to diffuse.
- Compare the arrangement and function of spongy mesophyll with palisade mesophyll.
Plant tissues
Students should be able to explain how the structures of plant tissues are related to their functions.
- Name the main plant tissues and state their functions.
- Relate structural features of each tissue, such as chloroplasts, air spaces or lignin, to its role.
- Explain how xylem, phloem and meristem tissues support transport and growth in plants.
Plant tissues
The leaf is a plant organ. Knowledge limited to epidermis, palisade and spongy mesophyll, xylem and phloem, and guard cells surrounding stomata.
- Label a leaf cross-section with epidermis, palisade mesophyll, spongy mesophyll, xylem, phloem, guard cells and stomata.
- Relate each named leaf tissue to its function in photosynthesis, gas exchange or transport.
- Explain how guard cells open and close stomata to balance gas exchange with water loss.
Plant tissues
xylem and phloem
- State the substance transported by xylem and the substance transported by phloem.
- Describe the direction of transport in xylem and in phloem.
- Relate the structure of xylem and phloem cells to their functions.
Poles of a magnet
A permanent magnet produces its own magnetic field. An induced magnet is a material that becomes a magnet when it is placed in a magnetic field. Induced magnetism always causes a force of attraction. When removed from the magnetic field an induced magnet loses most/all of its magnetism quickly.
- State that a permanent magnet produces its own magnetic field.
- Define an induced magnet and explain why induced magnetism always causes attraction.
- Describe how an induced magnet loses most or all of its magnetism quickly when removed from a magnetic field.
Poles of a magnet
Students should be able to describe:
- Describe the attraction and repulsion between unlike and like magnetic poles.
- Describe the difference between permanent magnets and induced magnets.
- Explain that induced magnetism always causes a force of attraction and is temporary.
Poles of a magnet
the attraction and repulsion between unlike and like poles for permanent magnets
- State the rule for attraction and repulsion between magnetic poles.
- Apply the rule to predict the force between two named poles.
- Describe a practical observation that demonstrates attraction and repulsion.
Poles of a magnet
the difference between permanent and induced magnets.
- State that a permanent magnet keeps its magnetism and an induced magnet only becomes magnetic in a magnetic field.
- Describe induced magnetism in iron or steel as always producing attraction towards the magnet.
- Use repulsion as evidence that an object is a permanent magnet rather than an induced one.
Poles of a magnet
The poles of a magnet are the places where the magnetic forces are strongest. When two magnets are brought close together they exert a force on each other. Two like poles repel each other. Two unlike poles attract each other. Attraction and repulsion between two magnetic poles are examples of non-contact force.
- Identify the poles of a magnet as the places where the magnetic force is strongest.
- Describe the forces between two magnets in terms of like poles repelling and unlike poles attracting.
- Classify attraction and repulsion between magnetic poles as non-contact forces.
Polymers
Polymers have very large molecules. The atoms in the polymer molecules are linked to other atoms by strong covalent bonds. The intermolecular forces between polymer molecules are relatively strong and so these substances are solids at room temperature.
- Describe polymers as very large molecules in which atoms are linked by strong covalent bonds.
- Explain why relatively strong intermolecular forces between polymer molecules make polymers solids at room temperature.
- Distinguish between covalent bonds within polymer chains and intermolecular forces between polymer chains when explaining melting behaviour.
Polymers
Students should be able to recognise polymers from diagrams showing their bonding and structure.
- Identify a polymer from a diagram showing a repeating unit or long chain.
- Describe the strong covalent bonding within polymer chains and the relatively strong intermolecular forces between them.
- Distinguish polymers from small molecules and giant covalent structures using diagrams.
Potable water
choosing an appropriate source of fresh water
- Identify rivers, lakes, reservoirs and aquifers as sources of fresh water and state that fresh water has low dissolved salt content.
- Compare two or more fresh water sources using criteria such as availability, contamination and treatment cost.
- Justify the selection of a fresh water source for a described local situation, referring to water quality and supply.
Potable water
describe the differences in treatment of ground water and salty water
- Describe the stages used to treat ground water to make it potable.
- Describe distillation and reverse osmosis as methods of desalination.
- Explain why salty water requires different treatment from ground water.
Potable water
distinguish between potable water and pure water
- Define potable water as water that is safe to drink and pure water as containing only H₂O molecules.
- Compare potable and pure water using boiling point, conductivity and evaporation residue.
- Apply a suitable practical test to classify a water sample as potable or pure.
Potable water
give reasons for the steps used to produce potable water.
- Describe the steps used to produce potable water from fresh water and from salty water.
- Explain why each step is needed by linking it to the impurity it removes.
- Compare filtration, chlorination and desalination in terms of the impurities they remove and their energy demands.
Potable water
If supplies of fresh water are limited, desalination of salty water or sea water may be required. Desalination can be done by distillation or by processes that use membranes such as reverse osmosis. These processes require large amounts of energy.
- State that desalination is used when fresh water supplies are limited.
- Describe how distillation and reverse osmosis separate water from dissolved salts.
- Explain why desalination processes require large amounts of energy and why this matters.
Potable water
In the United Kingdom (UK), rain provides water with low levels of dissolved substances (fresh water) that collects in the ground and in lakes and rivers, and most potable water is produced by:
- Describe how rain provides fresh water that collects in the ground, lakes and rivers in the UK.
- Describe the filtration and sterilisation steps used to produce most UK potable water.
- Explain the purpose of each treatment step in producing potable water.
Potable water
passing the water through filter beds
- Describe how water is passed through filter beds made of sand and gravel to remove insoluble particles.
- Explain why filtration produces clearer water but does not remove dissolved salts or all microorganisms.
- Place the filter bed stage correctly within the sequence of potable water treatment and link it to the need for sterilisation.
Potable water
Required practical activity 13: analysis and purification of water samples from different sources, including pH, dissolved solids and distillation.
- Carry out tests for pH and dissolved solids on water samples from different sources.
- Purify a water sample by distillation and collect the distillate safely.
- Compare the results before and after distillation to evaluate how effectively dissolved solids have been removed.
Potable water
Sterilising agents used for potable water include chlorine, ozone or ultraviolet light.
- Name chlorine, ozone and ultraviolet light as sterilising agents for potable water.
- Describe how each sterilising agent kills or inactivates microorganisms.
- Compare the advantages of chlorine, ozone and ultraviolet light as sterilising agents.
Potable water
sterilising.
- State that sterilising kills microorganisms in water.
- Describe the position of sterilising in the potable water treatment sequence.
- Explain why sterilising alone does not make water chemically pure.
Potable water
The methods used to produce potable water depend on available supplies of water and local conditions.
- Define potable water and distinguish it from pure water.
- Describe how the choice of water treatment method depends on the available supply.
- Explain how local conditions influence the method used to produce potable water.
Potable water
Water of appropriate quality is essential for life. For humans, drinking water should have sufficiently low levels of dissolved salts and microbes. Water that is safe to drink is called potable water. Potable water is not pure water in the chemical sense because it contains dissolved substances.
- Define potable water and explain why it is not pure water in the chemical sense.
- Describe how fresh water is treated to make it potable, including filtration and sterilisation.
- Describe desalination by distillation or reverse osmosis and recognise its energy demand.
Power
An energy transfer of 1 joule per second is equal to a power of 1 watt.
- Define the watt as one joule per second.
- Calculate power, energy transferred or time using P = E ÷ t.
- Convert between watts and kilowatts and between seconds and minutes in power problems.
Power
current, I, in amperes, A (amp is acceptable for ampere)
- Define electric current as the rate of flow of charge and state its unit, the ampere (A).
- Apply I = Q ÷ t and P = V I to calculate current, charge, time, power or potential difference.
- Explain how an ammeter is connected and interpret current values in series and parallel circuits.
Power
energy transferred, E, in joules, J
- Define energy transferred, E, and state its unit as the joule, J.
- Calculate energy transferred using E = P × t with consistent SI units.
- Convert energy values between joules, kilojoules and megajoules accurately.
Power
P = E / t
- Recall and apply the equation P = E / t to calculate power, energy or time.
- Convert between units of time and energy correctly before substitution.
- Explain that a higher power means the same energy is transferred in less time.
Power
P = I² R
- Apply P = I² R to calculate power, current or resistance in electrical circuits.
- Derive P = I² R from P = VI and V = IR.
- Interpret how current and resistance affect the rate of energy transfer in a component.
Power
P = V I
- Match each symbol in P = V I to its quantity and unit.
- Use P = V I to calculate power, potential difference or current from the other two quantities.
- Interpret a calculated power value as the rate of energy transfer in joules per second.
Power
P = W / t
- Recall and use the equation P = W / t to calculate power, work done or time.
- Convert between units of time and energy correctly before substitution.
- Explain that a watt is one joule per second and interpret power as a rate.
Power
potential difference, V, in volts, V
- Define potential difference as energy transferred per unit charge and state its unit, the volt (V).
- Apply V = W ÷ Q and P = V I to calculate potential difference, energy transferred, charge or power.
- Explain how a voltmeter is connected and interpret potential difference values in series and parallel circuits.
Power
power = current ² × resistance
- Select and apply power = current² × resistance to calculate power in a circuit.
- Rearrange the equation to determine current or resistance from power and one other quantity.
- Explain the effect of changing current on power dissipated at constant resistance.
Power
power = energy transferred / time
- Use power = energy transferred ÷ time to calculate power in watts.
- Convert time to seconds and energy to joules before substituting into the equation.
- Rearrange the equation to calculate energy transferred or time from the other two quantities.
Power
power = potential difference × current
- State the equation power = potential difference × current and identify the unit of each quantity.
- Calculate power from given values of potential difference and current, including after converting units.
- Rearrange the equation to determine an unknown potential difference or current from power and the other quantity.
Power
power = work done / time
- Apply power = work done / time to calculate power, work done or time.
- Calculate work done from force and distance and then use it in the power equation.
- Explain the difference between work done in joules and power in watts.
Power
Power is defined as the rate at which energy is transferred or the rate at which work is done.
- Define power as the rate of energy transfer or the rate of doing work.
- State that the watt is the unit of power and relate 1 W to 1 J/s.
- Compare the power of two devices that transfer different amounts of energy in different times.
Power
power, P, in watts, W
- Recall that power is measured in watts and that 1 W = 1 J/s.
- Convert between watts, kilowatts and megawatts accurately.
- Use the watt correctly when calculating power in mechanical and electrical contexts.
Power
resistance, R, in ohms, Ω
- Recall and apply the equation P = I²R.
- Rearrange the power equation to solve for resistance or current.
- Explain the heating effect of current in a resistor using the power equation.
Power
Students should be able to explain how the power transfer in any circuit device is related to the potential difference across it and the current through it, and to the energy changes over time:
- State and use the equation P = V I to calculate power in a circuit device.
- Explain how P = V I relates to energy transfer per second and how E = P t gives energy transferred over time.
- Use P = I² R to explain how power transfer in a resistor depends on current and resistance.
Power
Students should be able to give examples that illustrate the definition of power eg comparing two electric motors that both lift the same weight through the same height but one does it faster than the other.
- Define power as the rate of energy transfer or the rate of doing work.
- Calculate power using P = E ÷ t with consistent units.
- Explain, using a worked example, why the faster of two motors lifting the same load has the greater power.
Power
time, t, in seconds, s
- Define time, t, and state its unit as the second, s.
- Convert times from minutes and hours into seconds accurately.
- Calculate time taken using t = E ÷ P with consistent SI units.
Power
work done, W, in joules, J
- Calculate work done using W = F s with correct units.
- Convert distances and masses into SI units before substitution.
- Explain why work done equals energy transferred and how it links to power.
Principles of organisation
A tissue is a group of cells with a similar structure and function.
- Define a tissue as a group of cells with a similar structure and function.
- Give named examples of animal and plant tissues and state their functions.
- Explain how tissues fit into the hierarchy from cells to organ systems.
Principles of organisation
Cells are the basic building blocks of all living organisms.
- State that cells are the basic building blocks of all living organisms.
- Give examples of unicellular and multicellular organisms.
- Describe how cells relate to tissues, organs and organ systems in multicellular organisms.
Principles of organisation
Organs are aggregations of tissues performing specific functions.
- Define an organ as an aggregation of tissues performing specific functions.
- Identify at least two tissues within a named organ and state the function of each.
- Explain how the tissues of an organ cooperate to carry out the organ's overall function.
Principles of organisation
Organs are organised into organ systems, which work together to form organisms.
- Define an organ system as a group of organs working together.
- Give a named organ system with at least two organs and describe how they cooperate.
- Explain how organ systems interact to form a functioning organism.
Properties and effects of atmospheric pollutants
Carbon monoxide is a toxic gas. It is colourless and odourless and so is not easily detected.
- Describe the properties of carbon monoxide, including that it is toxic, colourless and odourless.
- Explain how carbon monoxide affects the body by reducing the oxygen carried by the blood.
- Relate the properties of carbon monoxide to the need for detectors and ventilation in homes and workplaces.
Properties and effects of atmospheric pollutants
Particulates cause global dimming and health problems for humans.
- State what particulates are and give a common source.
- Describe how particulates harm human health.
- Explain how particulates cause global dimming.
Properties and effects of atmospheric pollutants
Students should be able to describe and explain the problems caused by increased amounts of these pollutants in the air.
- Describe the effects of increased carbon monoxide, sulfur dioxide, nitrogen oxides and particulates on health and the environment.
- Explain how the properties of each pollutant lead to the problems it causes.
- Link combustion sources of pollutants to specific environmental or health consequences.
Properties and effects of atmospheric pollutants
Sulfur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain.
- State the sources of sulfur dioxide and oxides of nitrogen.
- Describe how these gases affect human respiratory health.
- Explain how these gases lead to acid rain and describe its environmental effects.
Properties of electromagnetic waves 1
(HT only) Different substances may absorb, transmit, refract or reflect electromagnetic waves in ways that vary with wavelength.
- State the four possible effects when electromagnetic waves meet a substance: absorption, transmission, refraction and reflection.
- Describe how the effect of a substance on electromagnetic waves can vary with wavelength, using a named example.
- Compare the behaviour of two different wavelengths in the same substance, or the same wavelength in two substances, using correct terminology.
Properties of electromagnetic waves 1
(HT only) Some effects, for example refraction, are due to the difference in velocity of the waves in different substances.
- Explain that refraction is caused by a change in the velocity of a wave when it passes between substances.
- Predict the direction of bending from whether a wave speeds up or slows down at a boundary.
- Use wave-speed changes to explain refraction at a boundary without claiming that frequency changes.
Properties of electromagnetic waves 1
(HT only) Students should be able to use wave front diagrams to explain refraction in terms of the change of speed that happens when a wave travels from one medium to a different medium.
- Describe how wave fronts behave when a wave crosses a boundary between two media.
- Explain refraction in terms of the change in wave speed and the pivoting of wave fronts.
- Relate the spacing of wave fronts to wavelength and wave speed in each medium.
Regulatory & Verification Details
- Qualification Number (QN)
- 601/8758/X
- Regulated Status
- Available to learners
- Awarding Body
- AQA
- Qualification Type
- GCSE (9 to 1)
- Operational Start
- Sept 2016