Question

How can a female be haemophilic?

(a) Mother is haemophilic and father is normal

(b) Mother is a carrier and father is haemophilic

(c) Both mother and father are carriers

(d) Both mother and father are haemophilic

I have been asked this question in a national level competition.

My question is from Inheritance and Variation Principles topic in section Principles of Inheritance and Variation of Biology – Class 12

Answer 1

Correct choice is (b) Mother is a carrier and father is haemophilic

The best explanation: A female can only be haemophilic if her mother is at least a carrier of this disease and her father is haemophilic. But the possibility of a female becoming haemophilic is extremely rare because being haemophilic for the parents at the later stage of life is unviable.