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Edexcel IGCSE Biology 2.88 nerve impulse speed

Edexcel IGCSE Biology 2.88 nerve impulse speed
Edexcel IGCSE Biology syllabusBiology 4BI1First assessment 2019

Practise interpreting neurone data, impulse speeds and response timing from graphs, calculations and method evaluations.

How this is tested

  • calculate impulse time from neurone length and speed, including unit conversion and standard form
  • interpret graphs comparing neurone diameter, myelin sheath and impulse speed
  • evaluate reaction-time methods by separating nerve impulse travel from brain decision time

Question 6(b)(i)

[Maximum number: 1]

Neurones transmit nerve impulses.
The diagram shows a neurone.

Figure for Question 6(b)(i) — Edexcel IGCSE Biology

Some neurones do not have a myelin sheath.

A scientist investigates the impulse speed for neurones with different diameters. She does this for neurones with a myelin sheath and neurones without a myelin sheath.

The graph shows the scientist's results.

Impulse speed in m per s

Figure for Question 6(b)(i) — Edexcel IGCSE Biology

Which conclusion is supported by the graph?

A

impulses are always faster in neurones with a myelin sheath

B

neurones always have a myelin sheath

C

wider neurones have a myelin sheath

D

wider neurones have faster impulses