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Science — CBSE Class 10 board question

Q1. [1]
Assertion (A) : Genes inherited from the parents decide the sex of a child. Reason (R) : X chromosome in a male child is inherited from his father.
  1. (a) Both (A) and (R) are true and (R) is the correct explanation of (A).
  2. (b) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
  3. (c) (A) is true, but (R) is false.
  4. (d) (A) is false, but (R) is true.
Previously asked in CBSE board exam
2023 31/1/1 Q18
Generated by claude-sonnet-4-6 · 2026-06-15 06:54 · grounding rag
Model Answer

(c) (A) is true, but (R) is false.

Assertion is correct — sex is genetically determined by chromosomes inherited from parents. But the Reason is false — a male child inherits his X chromosome from his mother, not his father; he inherits the Y chromosome from his father.

Explanation

The key fact: men are XY, women are XX. Every child gets X from the mother. The father contributes either X (girl) or Y (boy). So the X in a son comes from the mother, making (R) false. Assertion (A) is true as the textbook clearly states sex is determined by genes (chromosomes) inherited from parents.

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