Question

The gene of haemophilia is present on X chromosome. If a hemophilic male marries a normal female, the probability of their son being hemophilic is

• A. Nil
• B. 25%
• C. 50%
• D. 100%

Answer 1

The correct option is A Nil

• The mother is normal having the genotype X${}^H$X${}^H$. The father is affected having the genotype X${}^h$Y.
• The child receives one set of chromosomes from the mother and one set from the father.
• The child for being a male should receive the X${}^H$ chromosome from mother and Y chromosome from the father which will result the genotype of X${}^H$Y.
• So, there are no chances that the child will be hemophilic.
• Thus, the correct answer is option A.