O-LevelBiologyRespiration5090/11 · May/June 2021 · Q181 Mark

Why does oxygen enter the blood in the lungs?

AAerobic respiration takes place in the lungs.

BCarbon dioxide diffuses out of the blood into the alveoli.

CThe air in alveoli contains a higher concentration of oxygen than the blood in the lung capillaries.

DThe air in alveoli contains a lower concentration of oxygen than the blood in the lung capillaries.

✓ Correct answer

C: The air in alveoli contains a higher concentration of oxygen than the blood in the lung capillaries.

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Topic: Respiration, O-Level Biology (syllabus 5090). Multiple choice, 1 mark.
Source: O-Level Biology, May/June 2021 Paper 1 Variant 1, question 18.

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