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NEETZoologyNeural Control and Coordination

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Nerve fibres of the autonomous neural system do not possess nodes of Ranvier. Reason (R): Nerve fibres of the autonomous neural system are devoid of Schwann cells. In the light of the above statements, choose the most appropriate answer from the options given below:

Options

  1. ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
  2. BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
  3. C(A) is correct but (R) is not correct
  4. D(A) is not correct but (R) is correct

Correct answer

C. (A) is correct but (R) is not correct

Step-by-step solution

Assertion (A) is correct: The autonomous neural system is composed of unmyelinated nerve fibres. Nodes of Ranvier are defined as the gaps between adjacent myelin sheaths. Since unmyelinated fibres lack a myelin sheath, they do not possess nodes of Ranvier. Reason (R) is incorrect: According to NCERT, an unmyelinated nerve fibre is enclosed by a Schwann cell that does not form a myelin sheath around the axon. Therefore, these nerve fibres are not devoid of Schwann cells. Hence, (A) is correct but (R) is not correct.

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