CAIE A Level Biology 9700 · Transport in mammals
A marathon runner's leg muscle is actively contracting. Samples are taken from the blood in the femoral vein leaving the leg and from the tissue fluid surrounding the muscle cells.
Compare the composition of these two fluid samples. Using your knowledge of the properties of water, explain how blood helps to maintain a stable body temperature during the marathon run.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Compare means: Give similarities or differences between two things, and say which side each point belongs to. Write each point as a pair, for example: A is X, whereas B is Y. Two separate descriptions rarely earn the marks.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.