Question 1
Paper 2Medium16 marksAn electrical impulse was initiated at a point on the axon of a neuron. Detectors recorded the time at which the impulse reached different distances along the same axon. Figure 1 shows the results. Times and distances were recorded to the nearest 0.1 ms and 0.1 cm, respectively.
State what forms the cell body of a neuron, and give two differences between an axon and dendrites.
Use Figure 1 for parts (i) and (ii).
Describe the relationship between distance from the stimulation point and time of detection shown in Figure 1.
Determine the average speed of the impulse along the axon. Give your answer in m s⁻¹.
Use the best-fit line in Figure 1 to estimate the time at which the impulse would be detected 7.0 cm from the stimulation point.
Explain how the arrangement of a neuron’s fibres can enable it to conduct impulses over long distances and along multiple branches.
A student concludes that Figure 1 proves that all neurons conduct electrical impulses at the same speed. Evaluate this conclusion using Figure 1.