NEETZoologyPrinciples of Inheritance and Variation
A woman who is a carrier for both colour blindness and sickle cell anaemia marries a man who has normal vision but is a carrier for sickle cell anaemia. What is the probability that they will have a son who is both colour blind and afflicted with sickle cell anaemia?
Options
- A1 8
- B3 16
- C1 16
- D1 4
Correct answer
C. 1 16
Step-by-step solution
Colour blindness is an X-linked recessive trait, and sickle cell anaemia is an autosomal recessive trait. These traits assort independently. The mother is a carrier for both, so her genotype is X^ C X^ c Hb^ A Hb^ S . The father has normal vision and is a carrier for sickle cell anaemia, so his genotype is X^ C Y Hb^ A Hb^ S . For colour blindness: The cross X^ C X^ c X^ C Y yields X^ C X^ C , X^ C X^ c , X^ C Y , and X^ c Y . The probability of having a colour blind son ( X^ c Y ) out of all possible children is 1