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WAEC Biology 1995 Question 20

Question 20

Nervous Coordination

Which of the following is the correct route of transmission of impulses along a reflex arc?

  1. A.Receptor → sensory neurone → synapse → intermediate neurone → synapse → motor neurone → effector
  2. B.Receptor → motor neutron → synapse → intermediate neurone → synapse → sensory neurone→ effector
  3. C.Receptor → synapse → sensory neurone → intermediate neurone → synapse → effector → motor neurone
  4. D.Effector → motor neurone → synapse → sensory neurone → synapse → intermediate neurone → receptor
  5. E.Effector → intermediate neurone → synapse → motor neurone → synapse → sensory neurone → receptor
Show the answer and explanation

Answer: A (Receptor → sensory neurone → synapse → intermediate neurone → synapse → motor neurone → effector)

Explanation

The impulse goes receptor → sensory neurone → relay neurone → motor neurone → effector, crossing synapses between neurones.