CAIE A Level Biology 9700 · Gas exchange
Describe one structural feature of each of the following parts of the human gas exchange system that is adapted to its function:
(a) cartilage in the trachea (b) smooth muscle in bronchioles (c) ciliated epithelium in the bronchi (d) squamous epithelium of the alveoli
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.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.