A-LevelBiologyGas exchange9700/12 · Oct/Nov 2009 · Q311 Mark

An oxygen molecule diffuses directly from the air in an alveolus to haemoglobin in a red blood cell. What is the minimum number of cell surface membranes through which this molecule must pass?

✓ Correct answer

D: 5

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Topic: Gas exchange, A-Level Biology (syllabus 9700). Multiple choice, 1 mark.
Source: A-Level Biology, Oct/Nov 2009 Paper 1 Variant 2, question 31.

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