GS PrelimsScience and TechnologyInheritance and Evolution2009

In the context of genetic disorders, consider the following: A woman suffers from colour blindness while her husband does not suffer from it. They have a son and a daughter. In this context, which one of the following statements is most probably correct ?

A

Both children suffer from colour blindness.

B

Daughter suffers from colour blindness while son does not suffer from it.

C

Both children do not suffer from colour blindness.

D

Son suffers from colour blindness while daughter does not suffer from it.

Correct Answer: Option D

Explanation

1. Colour blindness is typically an X-linked recessive genetic disorder. 2. A woman suffers from colour blindness only if she has two copies of the recessive allele (XcXc). 3. Her husband does not suffer, meaning his genotype is XY. 4. Their son will inherit the Y chromosome from his father and one X chromosome from his mother. Since the mother is XcXc, the son must inherit an Xc chromosome, making his genotype XcY. Therefore, the son suffers from colour blindness. 5. Their daughter will inherit one X chromosome from her father (X) and one X chromosome from her mother (Xc). Her genotype will be XXc. Since the allele is recessive, she will be a carrier but does not suffer from colour blindness.

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