Question

If haemophilic female survives and marries a normal male, the theoretical ratio of their offspring regarding haemophilia will be.

• A. All offspring haemophilic
• B. All girls haemophilic
• C. All sons haemophilic
• D. $50\%$ of sons and $50\%$ daughters haemophilic

Answer 1

The correct option is C All sons haemophilic

Haemophilic female will have both the X chromosomes mutated. Hence, if a normal male mates with haemophilic female, then for a son to be born, the Y chromosome from male would combine with X chromosome of female, thus leading to (X'Y) where X chromosome will be the mutated one. All sons are haemophilic because this disease is caused by X-linked mutant gene.

So, the correct answer is 'All sons haemophilic'.