O-LevelBiologyEcology & Environment5090/11 · May/June 2014 · Q321 Mark

The list shows some changes that may occur in a lake that is polluted with nitrogen-containing fertiliser. 1 Concentration of oxygen decreases. 2 Decomposers feed on plants. 3 Green microorganisms grow and cover the surface. 4 Plants die. In which order do these changes occur?

A1→2→3→4

B2→1→4→3

C3→4→2→1

D4→3→1→2

✓ Correct answer

C: 3→4→2→1

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Topic: Ecology & Environment, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, May/June 2014 Paper 1 Variant 1, question 32.

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