CAIE A Level Biology 9700 · Control and coordination
In a laboratory, the conduction velocities of two sensory neurones from a frog were compared. Neurone A had a myelin sheath, while neurone B did not. The results showed that the action potential in neurone A travelled significantly faster than in neurone B.
Explain how the structure of a myelinated neurone allows saltatory conduction to increase the speed of impulse transmission.
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.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.