A firefighter completes a vigorous stair-climbing exercise and then rests. The firefighter continues to breathe deeply for several minutes after stopping.
Which statement describes the point at which the oxygen debt has been repaid?
All the lactic acid has been carried from the muscles to the liver
The breathing rate has started to fall but is still above the resting rate
The muscles have started to respire glucose aerobically again
All the lactic acid has reacted with oxygen and been removed
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.