O-LevelBiologyEcology & Environment5090/11 · May/June 2025 · Q401 Mark

DDT is an insecticide that is harmful to living organisms. It builds up in the cells of living organisms as it is not excreted. The diagram shows the path taken by DDT when it enters a lake. Which organisms would the DDT harm the most?

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Aaquatic plants

Bcarnivorous fish

Cherbivorous fish

Dfish-eating birds

✓ Correct answer

D: fish-eating birds

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Topic: Ecology & Environment, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, May/June 2025 Paper 1 Variant 1, question 40.

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