O-LevelBiologyEcology & Environment5090/11 · May/June 2012 · Q71 Mark

Two aquarium tanks are set up as shown. [Figure 7.1] After a week, all the animals in tank Y show signs of distress. This is because the animals have run out of

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Acarbon dioxide.

Bfood.

Cnitrate.

Doxygen.

✓ Correct answer

B: food.

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Topic: Ecology & Environment, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, May/June 2012 Paper 1 Variant 1, question 7.

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