CAIE A Level Biology 9700 · Control and coordination
A person eats a food containing chemicals that are detected by taste bud chemoreceptors on the tongue. Explain the sequence of events that leads from the detection of a chemical stimulus by a taste bud chemoreceptor to the generation of an action potential in a sensory neurone.
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.
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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