Question

Marriage between colour blind man and normal woman shall result in.

• A. Colour blind female progeny
• B. Colour blind male progeny
• C. Normal visioned female progeny
• D. Normal visioned male and female progeny

Answer 1

The correct option is D Normal visioned male and female progeny

Colour blindness is an X-linked recessive disorder. A colour blind man has a defective gene on X chromosome i.e X'Y and a normal woman has no defective gene i.e XY. (X'- defective gene, X-normal gene)Marriage between the colour blind and normal woman. If a child is male he inherits one normal X chromosome from mother and Y chromosome from father i.e XY. The male is with normal vision as X chromosome has no defective gene. If a child is female she inherits one normal X chromosome from mother and a defective X' chromosome from father i.e XX'.As a female progeny has defective gene only on one X chromosome its acts like carrier but she is not colour blind. A female must possess defective genes on both the X chromosomes to b colour blind.

So, the correct answer is 'option D'.