A-LevelBiologyGas exchangeOct/Nov 2009Paper 1 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?
A2
B3
C4
D5
✓ Correct Answer
The correct answer is D. This question tests the candidate's understanding of gas exchange within the Biologysyllabus. The examiner's mark scheme requires...
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
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