Topic: Sex-linked inheritance, Mendelian and chromosomal disorders· Genetics and Evolution

If a colour-blind man marries a woman who is homozygous for normal colour vision, the probability of their son being colour-blind is

1. 0·5

2. 0·75

3. 1

4. 0

Doubtly Asked 30 Oct 2026 NEET UG 2016 Phase 2 Practice test neet Save WhatsApp Report

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Answer: 4. 0

Colour blindness is X-linked recessive. Let the normal allele be X and the defective allele X^c.

Father: X^cY. Mother (homozygous normal): XX.

Sons receive the Y chromosome from the father and an X from the mother, so all sons are XY with a normal X. Probability of a colour-blind son = 0. (All daughters would be carriers.)

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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If a colour-blind man marries a woman who is homozygous for normal colour vision, the probability of their son being colour-blind is

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