O-LevelBiologyRespiration5090/12 · May/June 2021 · Q171 Mark

The graph shows the concentration of substance X in a person's blood, before, during and after exercise. [Figure 17.1] What is substance X?

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Aalcohol

Bglycogen

Clactic acid

Durea

✓ Correct answer

C: lactic acid

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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 2, question 17.

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