A-LevelBiologyGas exchangeMay/June 2023Paper 1 Q371 Mark
The average thicknesses for some structures in the human respiratory system are shown. [Figure 37.1] A molecule of oxygen is in the alveolar air space next to the wall of the alveolus. What is the shortest distance that the molecule needs to diffuse from its current position to the haemoglobin that completely fills a red blood cell in the nearest capillary? (Assume that the red blood cells touch the walls of a capillary.)
A595 nm
B600 nm
C605 nm
D610 nm
✓ Correct Answer
The correct answer is C: 605 nm
📋 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...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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