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4.2 Respiration

4.2 Respiration

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Question 12
H

Scientists measured the concentration of lactic acid in the blood of a trained athlete and of an untrained person while each of them exercised at increasing intensity. The figure shows the results.

Figure: The concentration of lactic acid in the blood of a trained athlete and an untrained person at increasing exercise intensity

image

a.

Determine the exercise intensity at which the blood lactic acid concentration of the untrained person reached 4.0 mmol/dm3 .

[1]
b.

Explain why the concentration of lactic acid in the blood rises as the exercise intensity increases.

[3]
c.

The lactic acid concentration of the trained athlete stays low until a higher exercise intensity than that of the untrained person. Suggest two reasons for this difference.

[2]
Markscheme

4.2 Respiration Questions

  1. GCSE
  2. /Biology
  3. /4.2 Respiration

51 exam-style questions on AQA GCSE Biology 4.2 Respiration, covering 4.2.1 Aerobic and anaerobic respiration, 4.2.2 Response to exercise, and 4.2.3 Metabolism. Each one has a worked solution and a mark scheme showing where the marks go.

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