Q1. [1] § 6.1.2 Human Brain
Assertion (A) : In our actions of writing or talking, our nervous system communicates with the muscles.
Reason (R) : Cranial nerves and spinal nerves form the peripheral nervous system.
- (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
- (C) Assertion (A) is true, but Reason (R) is false.
- (D) Assertion (A) is false, but Reason (R) is true.
Previously asked in CBSE board exam
2025 31/3/1 Q18
Generated by claude-sonnet-4-6 · 2026-06-15 06:48 · grounding rag
Model Answer
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). The brain sends messages to muscles via the nervous system for voluntary actions; the PNS definition is a separate fact.
Explanation
- A is true: The textbook states that for actions like writing and talking, "the brain also has to send messages to muscles" — this is the second way the nervous system communicates with muscles.
- R is true: The textbook explicitly states "the peripheral nervous system consisting of cranial nerves arising from the brain and spinal nerves arising from the spinal cord."
- R does NOT explain A: The PNS definition (R) merely names the components; it does not explain why or how the nervous system communicates with muscles during voluntary actions. Hence option (B).
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