During a short burst of climbing, oxygen reaches a mountain goat's leg muscles more slowly than the muscle cells use it, and the cells form lactic acid.
Which statement explains why less of the chemical energy in each glucose molecule is transferred to ATP than when the oxygen supply is sufficient?
Oxygen contains the chemical energy transferred to ATP, so a smaller oxygen supply gives a smaller yield.
Much of the chemical energy remains in the lactic acid because the glucose is broken down incompletely.
Glucose is broken down completely to lactic acid, but forming the lactic acid uses some of the ATP produced.
Lactic acid replaces glucose as the substance broken down to supply ATP, but transfers less chemical energy.
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.