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WAEC Biology 2018 Question 16

Question 16

Nervous Coordination

Which of the following statements about the response of neurones to stimulus is correct?

  1. A.Neurones respond to stimulus of any strength
  2. B.Neurones respond to all stimuli applied in rapid succession
  3. C.Neurones respond more rapidly during the absolute refractory period
  4. D.Intensity of stimulus must reach a threshold value before the neurones can be excited
Show the answer and explanation

Answer: D (Intensity of stimulus must reach a threshold value before the neurones can be excited)

Explanation

A neurone fires only when the stimulus reaches a minimum strength, the threshold. Weaker stimuli give no impulse, and during the refractory period it cannot fire at all.