Biology A (Salters-Nuffield)

    Pearson Edexcel
    A-Level

    Specification: 9BN0

    The PEARSON-EDEXCEL A-Level Biology A (Salters-Nuffield) specification covers 9 topics with 479 learning objectives (9BN0). Use the topic browser below to explore subtopics, exam tips, common mistakes, and key terminology for each area of the course.

    Starting Pearson Edexcel A-Level Biology A (Salters-Nuffield) this term? The whole specification is below, unit by unit.

    This subject will help you develop key knowledge and skills required for exam success.

    9

    Topics

    479

    Objectives

    508

    Exam Tips

    516

    Pitfalls

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    Official Specification

    Download the Pearson Edexcel A-Level Biology A (Salters-Nuffield) specification PDF

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    Key Features

    • Master key concepts
    • Develop exam technique
    • Apply knowledge effectively

    About Pearson Edexcel A-Level Biology A (Salters-Nuffield)

    The Pearson Edexcel A-Level Biology A (Salters-Nuffield) course is a context-led approach that explores biology through real-world applications and contemporary issues. You will study topics such as lifestyle, health, and risk; genes and health; voice of the genome; biodiversity and natural resources; and on the wild side, among others. The specification is structured into four themes: The Nature of Life, Genes and Health, Voice of the Genome, and Biodiversity and Natural Resources, each divided into topics that build on core concepts.

    This course emphasises the development of practical skills and scientific understanding through a series of core practicals and a practical endorsement. It encourages you to think critically about ethical, social, and environmental issues in biology. The Salters-Nuffield approach is designed to make biology relevant and engaging, linking theory to real-life contexts and current scientific research.

    Assessment Structure

    The Pearson Edexcel A-Level Biology A (Salters-Nuffield) is assessed through three written exams and a separate practical endorsement. Paper 1: The Natural Environment and Species Survival (2 hours, 100 marks, 33.3% of A-Level) covers topics 1-6. Paper 2: Energy, Exercise and Coordination (2 hours, 100 marks, 33.3% of A-Level) covers topics 7-10. Paper 3: General and Practical Applications in Biology (2 hours, 100 marks, 33.3% of A-Level) covers all topics and includes a pre-released scientific article. The practical endorsement is assessed separately and reported as pass/fail; it does not contribute to the A-Level grade but is required for the practical skills endorsement.

    Why Choose Pearson Edexcel?

    • The Salters-Nuffield course is context-led, meaning you learn biological concepts through engaging, real-world scenarios, which can make the material more memorable and relevant to everyday life.
    • It has a strong focus on practical skills and scientific investigation, with a dedicated practical endorsement that can be advantageous for university applications in biological sciences.
    • The specification includes a pre-released scientific article for Paper 3, which develops your ability to critically analyse and interpret scientific information, a skill highly valued by universities and employers.

    Frequently Asked Questions

    Common Exam Mistakes

    Pitfalls to avoid in your exams

    • •Thinking that all mutations are harmful; correction: mutations can be neutral, beneficial or harmful depending on their effect on the protein and the organism.
    • •Stating that a substitution always changes the amino acid sequence; correction: the genetic code is degenerate, so a substitution may not change the amino acid (silent mutation).
    • •Confusing the effect of a three-nucleotide deletion with a frameshift; correction: deletion of three nucleotides removes one amino acid without shifting the reading frame, whereas deletion of one or two nucleotides causes a frameshift.
    • •Believing that cystic fibrosis is caused by a single mutation; correction: many different mutations in the CFTR gene can cause the disease, and different patients may have different mutations.
    • •Writing that RNA contains thymine; correct this by stating RNA contains uracil instead of thymine.
    • •Saying that condensation joins nucleotides by hydrogen bonds; correct this by stating condensation forms phosphodiester bonds and releases water.
    • •Mixing up the base pair rules; correct this by pairing adenine with thymine (or uracil in RNA) and cytosine with guanine.
    • •Confusing MRI with fMRI: MRI shows structure, while fMRI shows function by detecting blood oxygenation changes; correct by linking MRI to anatomy and fMRI to activity mapping.

    Top Examiner Tips

    Expert advice for exam success

    • •When describing a mutation, state the type of change (substitution, insertion, deletion), the effect on the codon and the consequence for the polypeptide.
    • •For cystic fibrosis, name the gene (CFTR), describe the protein (chloride ion channel) and explain how a specific mutation such as F508del affects protein folding and function.
    • •Use the terms missense, nonsense and frameshift accurately, and link them to the effect on the primary, secondary and tertiary structure of the protein.
    • •Practise explaining how a change in DNA sequence can lead to a change in the phenotype, using the CFTR example to connect genotype to protein function and symptoms.
    • •When drawing a nucleotide, label the phosphate, pentose sugar and base, and state whether the sugar is deoxyribose or ribose.
    • •For DNA structure, mention complementary base pairing, hydrogen bonding between strands and the antiparallel double helix.
    • •Use the condensation reaction description to explain how a dinucleotide forms and identify the water molecule released.
    • •For comparison questions, organise answers by technique and include the physical principle, what is measured, a diagnostic use and one limitation.

    Specification Topics

    9 topics

    Topic 2: Genes and Health

    Errors during DNA replication, such as base substitution, insertion or deletion, can change the nucleotide sequence. A substitution may alter one codon and hence one amino acid, while insertions or deletions can shift the reading frame, altering many amino acids and often producing a non-functional protein. Cystic fibrosis results from mutations in the CFTR gene, which encodes a chloride ion channel. Many different mutations can cause the disease, including the common deletion of three nucleotides that removes phenylalanine at position 508 (F508del). This misfolds the protein, so it is degraded before reaching the membrane, reducing chloride transport and leading to thick mucus in the lungs and pancreas.

    2.12 i) Understand how errors in DNA replication can give rise to mutations. ii) Understand how cystic fibrosis results from one of a number of possible gene mutations., 2.5 i) Know the basic structure of mononucleotides (deoxyribose or ribose linked to a phosphate and a base, including thymine, uracil, cytosine, adenine or guanine) and the structures of DNA and RNA (polynucleotides composed of mononucleotides linked through condensation reactions). ii) Know how complementary base pairing and the hydrogen bonding between two complementary strands are involved in the formation of the DNA double helix., 2.1 i) Know the properties of gas exchange surfaces in living organisms (large surface area to volume ratio, thickness of surface, difference in concentration). ii) Understand how the rate of diffusion is dependent on these properties and can be calculated using Fick’s Law of Diffusion. iii) Understand how the structure of the mammalian lung is adapted for rapid gaseous exchange. +15 more

    55 objectives58 tips60 pitfalls18 subtopics

    Topic 8: Grey Matter

    MRI uses strong magnetic fields and radio waves to align hydrogen nuclei; emitted signals build high-resolution images of soft tissue, so it reveals brain structure such as tumours, lesions and atrophy without ionising radiation. fMRI detects changes in blood oxygenation as a proxy for neural activity, mapping active brain regions during tasks and so investigating function. PET uses a radioactive tracer, often fluorodeoxyglucose labelled with fluorine-18, which emits positrons; annihilation produces gamma rays detected to show metabolic activity, useful for tumours and functional mapping. CT uses multiple X-ray projections from different angles to construct cross-sectional images; it is fast and excellent for bone and acute bleeding but uses ionising radiation. Together these techniques support diagnosis and investigation of brain structure and function.

    8.9 Understand how magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), positron emission tomography (PET) and computed tomography (CT) scans are used in medical diagnosis and the investigation of brain structure and function., 8.17 Know how drugs can be produced using genetically modified organisms (plants, animals and microorganisms)., 8.2 i) Understand how the nervous systems of organisms can cause effectors to respond to a stimulus. ii) Understand how the pupil dilates and contracts. +17 more

    60 objectives62 tips62 pitfalls20 subtopics

    Topic 5: On the Wild Side

    Ecology uses nested terms. A habitat is the place where an organism lives, defined by its physical features, such as a rocky shore or a hedgerow. A population is all the organisms of one species in a habitat at one time. A community is all the populations of different species living and interacting in the same habitat. An ecosystem is the community plus the non-living surroundings it interacts with, so energy flow and nutrient cycling are included. For example, in a pond, the habitat is the water and mud; the population could be all the great crested newts; the community includes newts, pondweed and water fleas; the ecosystem adds light, temperature, oxygen and minerals.

    5.1 Understand the terms ecosystem, community, population and habitat., CORE PRACTICAL 13: Investigate the effects of temperature on the development of organisms (such as seedling growth rate, brine shrimp hatch rates)., 5.20 Understand the way in which scientific conclusions about controversial issues, such as what actions should be taken to reduce climate change or the degree to which humans are affecting climate change, can sometimes depend on who is reaching the conclusions. +23 more

    78 objectives86 tips86 pitfalls26 subtopics

    Topic 1: Lifestyle, Health and Risk

    Epidemiological studies link exposures, such as saturated fat intake or smoking, to health outcomes. To evaluate design, judge whether the sample was selected without bias and was large enough, then whether the resulting data are valid and reliable. A cohort followed for years gives incidence; a case-control study compares past exposures of people with and without heart disease. Ask who was recruited, how, and who was left out: a survey of one gym may under-represent the elderly or low-income groups, so findings cannot be generalised. Small samples give wide confidence intervals and unstable estimates, so a risk ratio from 30 people is weak evidence. Valid data measure what they claim: a food-frequency questionnaire may misreport portion size, whereas measured blood cholesterol is more objective. Reliable data give consistent results on repeat testing or in other populations.

    1.9 Be able to evaluate the design of studies used to determine health risk factors, including sample selection and sample size used to collect data that is both valid and reliable., 1.5 Understand the course of events that leads to atherosclerosis (endothelial dysfunction, inflammatory response, plaque formation, raised blood pressure)., 1.15 i) Be able to analyse and interpret data on the possible significance for health of blood cholesterol levels and levels of high-density lipoproteins (HDLs) and low-density lipoproteins (LDLs). ii) Know the evidence for a causal relationship between blood cholesterol levels (total cholesterol and LDL cholesterol) and cardiovascular disease (CVD). +17 more

    60 objectives65 tips66 pitfalls20 subtopics

    Topic 4: Biodiversity and Natural Resources

    In this core practical you prepare a stained transverse section of a herbaceous stem and use a light microscope to locate three tissues. Sclerenchyma fibres form caps outside the phloem, with thick lignified walls and small lumens. Phloem sieve tubes sit in the outer vascular bundle, with sieve plates and companion cells. Xylem vessels lie towards the stem interior, wide and lignified, carrying water and mineral ions. Scan at low power to find a vascular bundle, then increase magnification to identify each tissue by wall thickness, lumen size and position. Draw a labelled plan and a high-power detail, recording magnification.

    CORE PRACTICAL 6: Identify sclerenchyma fibres, phloem sieve tubes and xylem vessels and their location within stems through a light microscope., 4.9 Understand the structure and function of the polysaccharides starch and cellulose, including the role of hydrogen bonds between β -glucose molecules in the formation of cellulose microfibrils., 4.15 Understand how the uses of plant fibres and starch may contribute to sustainability, including plant-based products to replace oil-based plastics. +17 more

    60 objectives64 tips66 pitfalls20 subtopics

    Topic 3: Voice of the Genome

    The cell is the basic unit of every living organism, from a bacterium to a blue whale. All cells are bounded by a plasma membrane, a phospholipid bilayer that controls what enters and leaves. Inside is cytoplasm, where metabolism occurs, and genetic material in the form of DNA, which stores the instructions for proteins. Ribosomes are present in every cell and assemble polypeptides. These shared features define life and allow organisms to be grouped. For example, a human liver cell and a wheat root cell both have a membrane, cytoplasm, DNA and ribosomes, yet differ in size and internal detail. Recognising the common core lets you compare prokaryotic and eukaryotic cells and explain why viruses, which lack these features, are not classed as living organisms.

    3.1 Know that all living organisms are made of cells, sharing some common features., 3.13 Understand how the cells of multicellular organisms are organised into tissues, tissues into organs and organs into systems., 3.8 i) Know that a locus (plural = loci) is the location of genes on a chromosome. ii) Understand the linkage of genes on a chromosome and sex linkage. +13 more

    50 objectives50 tips51 pitfalls16 subtopics

    Topic 6: Immunity, Infection and Forensics

    A gene is a DNA sequence that is transcribed to produce pre-mRNA, which is then processed into mature mRNA. Post-transcriptional changes to mRNA allow one gene to produce multiple proteins. These changes include alternative splicing, where different combinations of exons are joined and introns removed, producing different mRNA variants from the same pre-mRNA. Alternative polyadenylation can produce mRNAs with different 3′ ends, affecting stability or localisation. RNA editing can alter nucleotides, changing codons. These mRNA variants are translated into proteins with different amino acid sequences. For example, the human calcitonin gene produces calcitonin in thyroid C cells and calcitonin gene-related peptide (CGRP) in neurones via alternative splicing and polyadenylation. Thus, one gene can give rise to more than one protein through post-transcriptional changes to mRNA.

    6.10 Understand how one gene can give rise to more than one protein through post- transcriptional changes to messenger RNA (mRNA)., 6.1 Understand how to determine the time of death of a mammal by examining the extent of decomposition, stage of succession, forensic entomology, body temperature and degree of muscle contraction., 6.15 Know how an understanding of the contributory causes of hospital acquired infections have led to codes of practice regarding antibiotic prescription and hospital practice that relate to infection prevention and control. +14 more

    51 objectives55 tips55 pitfalls17 subtopics

    Topic 7: Run for your Life

    Movement results from interaction between muscles, tendons, skeleton and ligaments. Muscles contract to generate force; tendons attach muscle to bone and transmit force; bones act as levers; ligaments connect bone to bone and stabilise joints. Antagonistic pairs work opposite each other: as one contracts (agonist), the other relaxes (antagonist), enabling controlled movement. Extensors increase joint angle (e.g., triceps brachii at elbow), flexors decrease joint angle (e.g., biceps brachii). Example: elbow flexion involves biceps contracting and triceps relaxing; extension reverses this.

    7.1 Know the way in which muscles, tendons, the skeleton and ligaments interact to enable movement, including antagonistic muscle pairs, extensors and flexors., 7.7 Understand what happens to lactate after a period of anaerobic respiration in animals., 7.13 Understand the analysis and interpretation of data relating to possible disadvantages of exercising too much (wear and tear on joints, suppression of the immune system) and exercising too little (increased risk of obesity, cardiovascular disease (CVD) and diabetes), recognising correlation and causal relationships. +15 more

    54 objectives58 tips58 pitfalls18 subtopics

    Assessment Objectives

    AO3 is the assessment objective that rewards thinking with scientific material rather than recalling it. You must analyse information by breaking it into parts and identifying relationships, interpret it by explaining what the data or evidence means in biological terms, and evaluate it by weighing strengths, weaknesses and reliability. When the material concerns an issue, such as a medical, environmental or ethical application, you must reason about it and reach a supported judgement or conclusion. AO3 also covers practical work: you develop a design by identifying variables and controls, and refine procedures by proposing specific improvements justified by evidence. For example, given a table of enzyme rates, identify the trend, explain it using collision theory, judge whether the evidence supports the claim, and suggest a controlled improvement.

    AO3: Analyse, interpret and evaluate scientific information, ideas and evidence, including in relation to issues, to: make judgements and reach conclusions; develop and refine practical design and procedures, AO2: Apply knowledge and understanding of scientific ideas, processes, techniques and procedures: in a theoretical context; in a practical context; when handling qualitative data; when handling quantitative data, AO1: Demonstrate knowledge and understanding of scientific ideas, processes, techniques and procedures

    11 objectives10 tips12 pitfalls3 subtopics

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