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4.2 Respiration

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Question 16

A scientist divides an aerobic bacterial culture into two samples containing the same number of cells. Sample X is kept at 25 °C for 10 minutes. Sample Y is heated to 65 °C for 10 minutes. Both samples are then placed at 25 °C with sufficient glucose and oxygen. The rate of oxygen uptake is measured immediately and again after 30 minutes.

Which result best supports the conclusion that heating sample Y permanently denatured enzymes controlling respiration?

[1]
A

Sample Y has a much lower rate of oxygen uptake than sample X both immediately and after 30 minutes.

B

Sample Y has a much higher rate of oxygen uptake than sample X both immediately and after 30 minutes.

C

Samples X and Y have the same rate of oxygen uptake both immediately and after 30 minutes.

D

Sample Y has a lower rate of oxygen uptake at first but the same rate as sample X after 30 minutes.

Markscheme

4.2 Respiration Questions

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

92 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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