CAIE A Level Biology 9700 · Gas exchange
A student examines slides of a transverse section of the trachea and a transverse section of a bronchiole. She notes clear differences in the distribution of cartilage and smooth muscle.
Explain how the structure of the trachea differs from that of a bronchiole in terms of cartilage and smooth muscle, and how each difference relates to the function of the respective airway.
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.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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