This exam focus covers Exam Focus within Decomposition for GCSE Biology. Topic 4: Decomposition It is section 9 of 11 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Topic position
Section 9 of 11
Practice
15 questions
Recall
20 flashcards
🎯 Exam Focus
Frequently ExaminedDecomposition is examined regularly on AQA Paper 2, often in the context of the Required Practical (RPA6/RPA10 — investigating factors affecting decomposition rate). Questions frequently link decomposition to the carbon cycle and nutrient recycling. Key patterns:
- Factor explanation questions (2–3 marks): "Explain how temperature affects the rate of decomposition" — always link to enzyme activity, state the optimum, and explain denaturation at high temperatures.
- Required Practical questions (3–4 marks): "Describe how you would investigate the effect of moisture on the rate of decomposition" — state the independent variable, dependent variable, control variables, and how you would measure the rate.
- Comparison questions (2–3 marks): "Explain why decomposition is slower in peat bogs than in garden soil" — link to anaerobic conditions, low pH, and reduced enzyme activity.
- Biogas questions (2–3 marks): State conditions needed for biogas production and explain why anaerobic conditions are necessary.
Common mark-losing errors: Saying "bacteria eat dead material" rather than secreting enzymes externally; saying high temperature always speeds decomposition (ignoring denaturation); forgetting fungi as major decomposers; confusing decomposers with detritivores.