During recovery after a difficult climb, a blood sample from a vessel entering a mountaineer's liver contains lactic acid. A student claims that this shows the lactic acid was produced by liver cells. Which evaluation is best?
The claim is supported, because the lactic acid may have been released by liver cells into the blood entering the liver
The claim is not supported, because the lactic acid may have been converted into glucose by the muscles instead of the liver
The claim is supported, because the lactic acid may have been produced by aerobic respiration in the liver cells
The claim is not supported, because the lactic acid may have been transported from the working muscles to the liver
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.