O-LevelBiologyEcology & Environment5090/11 · Oct/Nov 2010 · Q281 Mark

Nitrates in the soil can be absorbed by plants. Nitrates can also be removed from the soil by the action of

Abacteria in the root nodules of legumes.

Bdenitrifying bacteria in poorly aerated conditions.

Cnitrogen-fixing bacteria on ammonium compounds.

Dnitrogen-fixing bacteria on decaying plants.

✓ Correct answer

B: denitrifying bacteria in poorly aerated conditions.

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Topic: Ecology & Environment, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, Oct/Nov 2010 Paper 1 Variant 1, question 28.

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