CAIE A Level Biology 9700 · Control and coordination
A student investigates the effect of myelination on the speed of impulse conduction. They compare two nerve fibres: fibre A is a myelinated neurone from a frog, fibre B is a non-myelinated neurone from an earthworm. They stimulate each at one end and measure the time taken for the impulse to reach the other end. They find that conduction is much faster in fibre A.
Compare the mechanisms of impulse conduction in fibre A and fibre B.
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.
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.