Global challenges

OCR

GCSE

This topic necessitates a critical evaluation of the scientific principles underpinning sustainable development and the management of Earth's finite resources. Candidates must analyse methods for producing potable water, distinguishing between pure and potable water, and evaluate the processes of desalination, waste-water treatment, and phytomining. The study extends to Life Cycle Assessments (LCAs) to quantify environmental footprints from cradle to grave, alongside a rigorous examination of atmospheric chemistry, specifically the greenhouse effect, climate change correlations, and the impact of pollutants like sulfur dioxide and particulates.

Objectives

Exam Tips

Pitfalls

Key Terms

Mark Points

Subtopics in this area

Global challenges

What You Need to Demonstrate

Key skills and knowledge for this topic

Award 1 mark for specifying the use of a 'random number generator' to determine quadrat coordinates to avoid bias
Credit responses that link 'selective breeding' to the selection of parents with desired characteristics repeated over many generations
Award 1 mark for distinguishing between 'communicable' (pathogen-caused) and 'non-communicable' (lifestyle/genetic) diseases
Credit evaluation of GM crops that contrasts increased yield/resistance with potential reduction in biodiversity or gene transfer to wild relatives
Award marks for explaining that vaccination stimulates white blood cells to produce specific antibodies and memory cells
Award 1 mark for explicitly stating that short wavelength radiation passes through the atmosphere while long wavelength (thermal) radiation is absorbed by greenhouse gases.
Credit responses that distinguish between 'potable water' (safe to drink) and 'pure water' (no dissolved substances) using specific chemical tests.
Award marks in Life Cycle Assessments (LCAs) only when specific environmental impacts are linked to stages (e.g., 'mining raw materials causes habitat destruction' rather than just 'it is bad for the environment').

Example Examiner Feedback

Real feedback patterns examiners use when marking

"You identified the correct sampling method, but didn't explain *how* to ensure it was random (e.g., random number generator)"
"Be careful not to confuse antibiotics (kill bacteria) with antibodies (produced by white blood cells)"
"When evaluating GM crops, make sure to give a conclusion based on the evidence provided in the question"
"You mentioned breeding the 'best' animals, but to get the marks you must specify that this process is repeated over 'many generations'"
"You have identified the correct gas, but you must explain *how* it interacts with infrared radiation to get the explanation mark."
"Avoid generic terms like 'pollution'; specify whether you mean CO2 emissions, toxic runoff, or landfill waste."
"Good use of the graph, but you need to distinguish between correlation and causation when discussing these climate trends."
"For the water treatment question, make sure you separate the removal of solids (filtration) from the killing of bacteria (chlorination/sterilisation)."

Marking Points

Key points examiners look for in your answers

Award 1 mark for specifying the use of a 'random number generator' to determine quadrat coordinates to avoid bias
Credit responses that link 'selective breeding' to the selection of parents with desired characteristics repeated over many generations
Award 1 mark for distinguishing between 'communicable' (pathogen-caused) and 'non-communicable' (lifestyle/genetic) diseases
Credit evaluation of GM crops that contrasts increased yield/resistance with potential reduction in biodiversity or gene transfer to wild relatives
Award marks for explaining that vaccination stimulates white blood cells to produce specific antibodies and memory cells
Award 1 mark for explicitly stating that short wavelength radiation passes through the atmosphere while long wavelength (thermal) radiation is absorbed by greenhouse gases.
Credit responses that distinguish between 'potable water' (safe to drink) and 'pure water' (no dissolved substances) using specific chemical tests.
Award marks in Life Cycle Assessments (LCAs) only when specific environmental impacts are linked to stages (e.g., 'mining raw materials causes habitat destruction' rather than just 'it is bad for the environment').
Candidates must link selective breeding or genetic modification directly to specific desired traits (e.g., disease resistance, increased yield) to gain credit.

Examiner Tips

Expert advice for maximising your marks

💡When asked to describe a sampling method, always include the instruction to 'repeat and calculate a mean' to ensure validity
💡In questions about disease, explicitly name the type of pathogen (bacteria, virus, fungus, protist) rather than using generic terms like 'germs'
💡For 'evaluate' questions on food security, structure your answer with evidence for and against before stating a justified conclusion
💡Use the term 'resistant' not 'immune' when describing bacteria that survive antibiotic treatment
💡In 6-mark Level of Response questions regarding LCAs, ensure you compare both products across all four life stages to access Level 3.
💡When describing climate change trends, explicitly quote data points from provided graphs to support your description; general trends often fail to secure full marks.
💡Memorise the specific tests for water purity (boiling point at exactly 100°C) as this is a frequent discriminator against 'clean' water.

Common Mistakes

Pitfalls to avoid in your exam answers

Stating that antibiotics kill viruses; examiners reject this as a fundamental error as antibiotics only affect bacteria
Describing sampling as 'throwing' quadrats randomly rather than placing them at coordinates generated by a random number generator
Confusing the mechanism of vaccination (producing memory cells for future immunity) with the immediate curative action of antibiotics
Failing to reference 'alleles' or 'genes' when explaining the process of selective breeding or genetic modification
Conflating ozone layer depletion with the greenhouse effect; examiners reject answers suggesting CFCs or ozone holes cause global warming.
Stating that greenhouse gases 'reflect' radiation; the correct term is 'absorb' and 're-emit' thermal radiation.
Providing vague answers for LCAs such as 'less pollution' without specifying the type (e.g., CO2 emissions, landfill waste, toxicity).
Confusing the processes of 'filtration' (removing solids) and 'sterilisation' (killing microbes) in water treatment descriptions.

Key Terminology

Essential terms to know

Potable water production and treatment processes

Life Cycle Assessments (LCAs) and material sustainability

The Greenhouse Effect and Global Climate Change mechanisms

Atmospheric pollutants: origins and environmental impacts

Alternative methods of metal extraction (Phytomining/Bioleaching)

Composition and evolution of the Earth's atmosphere

The greenhouse effect and climate change mechanisms

Potable water production and waste water treatment

Life Cycle Assessments (LCAs) and sustainable resource use

Atmospheric pollutants and their environmental impact

Likely Command Words

How questions on this topic are typically asked

Describe

Explain

Calculate

Evaluate

Suggest

Compare

Practical Links

Related required practicals

•{"code":"PAG B3","title":"Sampling techniques","relevance":"Use of quadrats and transects to measure abundance and distribution of organisms"}
•{"code":"PAG C8","title":"Analysis and purification of water samples","relevance":"Testing for dissolved solids and distillation techniques"}

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