CAIE A Level Biology 9700 · Transport in mammals
An athlete is running a long-distance race. In the leg muscles, there is an increased demand for oxygen and glucose, and a need to remove carbon dioxide and lactic acid. Describe, using named examples of vessels, how the structure of the blood vessels in the leg muscles facilitates this exchange and how tissue fluid is formed to support the muscle cells.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
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