A-LevelBiologyGas exchange9700/12 · Oct/Nov 2020 · Q331 Mark

The partial pressure of oxygen in air inside alveoli is 14 kPa. The partial pressure of oxygen in pulmonary capillaries is 6 kPa. What will be the effect of these partial pressures on diffusion?

ACarbon dioxide will not diffuse in any direction.

BOxygen will diffuse from alveoli into capillaries.

COxygen will diffuse from capillaries into alveoli.

DOxygen will diffuse equally in both directions.

✓ Correct answer

B: Oxygen will diffuse from alveoli into capillaries.

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Topic: Gas exchange, A-Level Biology (syllabus 9700). Multiple choice, 1 mark.
Source: A-Level Biology, Oct/Nov 2020 Paper 1 Variant 2, question 33.

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