A volunteer squeezes a handgrip repeatedly until the forearm muscles are fatigued. Two minutes after the squeezing stops, a blood sample is found to contain lactic acid. The volunteer concludes from this result that anaerobic respiration is still going on in the forearm muscles at the moment of sampling. Which is the best evaluation of the conclusion?
Not justified, as lactic acid made during the squeezing may not yet have been removed from the blood
Justified, as lactic acid is made when extra oxygen is used to repay the oxygen debt
Not justified, as the lactic acid is made in the liver and then carried to the forearm
Justified, as lactic acid is also made by aerobic respiration in muscles during recovery
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.