A delivery worker repeatedly carries heavy parcels upstairs. After the worker stops, the heart rate remains above the resting rate for several minutes.
Why does the worker's heart rate stay high after the activity has stopped?
Blood must carry lactic acid to the liver and supply the oxygen needed to remove it.
Blood must carry lactic acid to the kidneys so that it can be removed in the urine.
Blood must carry glucose to the muscles so that they can keep respiring anaerobically.
Blood must carry lactic acid to the lungs so that it can be breathed out as a gas.
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.