Case study·Standard multi-step (3/5)·No calculator
Difficulty guide
The label describes the problem, not your ability.
1/5 - Foundational
Warm-up setup; checks one basic idea.
2/5 - Routine exam skill
Normal syllabus skill; usually one main rule or interpretation.
3/5 - Standard multi-step
Exam-style problem with multiple steps or a common trap.
4/5 - Hard exam skill
High-end exam problem; combines methods carefully.
5/5 - Challenge
Stretch problem beyond normal exam pressure.
Question
The figure shows concentration of a persistent pesticide in a pond food chain.
Total: 5 marks
(a) Which organism has the lowest pesticide concentration? (1 mark)
(b) Calculate how many times higher the concentration is in the bird than in the large fish. (1 mark)
(c) Name the process shown. (1 mark)
(d) Why does this process threaten top consumers? (2 marks)
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