NEET2005ZoologyPrinciples of Inheritance and VariationActual
A woman with normal vision, but whose father was colour blind, marries a colour blind man. Suppose that the fourth child of this couple was a boy. This boy:
Options
- Amay be colourblind or may be of normal vision
- Bmust be colour blind
- Cmust have normal colour vision
- Dwill be partially colour blind since he is heterozygous for the colourblind mutant allele.
Correct answer
A. may be colourblind or may be of normal vision
Step-by-step solution
The woman has normal vision but her father was colour blind so she should be the carrier to the disease as Colour blindness is an X-Linked recessive disorder. The genotype of the woman would be: 22 AA + XX ^ C The genotype of man to be colour blind should be: 22 AA + X ^ C Y The probability of Male child to be colour blind will 50 % and the ratio of diseased to a normal male child is 1: 1 .