A-LevelBiologyGas exchangeFeb/Mar 2023Paper 1 Q361 Mark

Two of the requirements of an efficient gas exchange system are a large surface area and a short diffusion distance. Which row correctly describes how alveoli are adapted to meet these requirements?

Q: What topic does this question test?

This question tests Gas exchange in A-Level Biology (syllabus code 9700). It is worth 1 mark.

Aelastin fibres prevent the alveolus wall from collapsing; an extracellular layer inside the alveolus wall contains blood capillaries

Bgases dissolve in a layer of liquid to speed up diffusion; alveolar walls are next to capillaries

Calveoli are folded and interconnected; walls of alveoli are only one cell thick

Dwalls of alveoli are formed of squamous epithelial cells; red blood cells are very close to capillary walls

✓ Correct Answer

The correct answer is C: alveoli are folded and interconnected; walls of alveoli are only one cell thick

📋 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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About This A-Level Biology Question

Topic

This multiple-choice question tests Gas exchange in A-Level Biology (syllabus code 9700). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Biology Feb/Mar 2023 examination, Paper 1 Variant 2.

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