O-LevelBiologyRespiration5090/11 · May/June 2017 · Q271 Mark

The diagram shows a simple apparatus that could be used to produce alcohol. What is the role of the U-shaped tube containing water?

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Ato keep bacteria in and oxygen in

Bto keep bacteria in and oxygen out

Cto keep bacteria out and oxygen in

Dto keep bacteria out and oxygen out

✓ Correct answer

D: to keep bacteria out and oxygen out

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Topic: Respiration, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, May/June 2017 Paper 1 Variant 1, question 27.

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