Question

If father is normal while mother is carrier of haemophilia.

• A. All female offspring will be carriers
• B. A male offspring has $50\%$ chance of active disease
• C. A female offspring has $50\%$ chance of active disease
• D. All female offspring will be normal

Answer 1

The correct option is B A male offspring has $50\%$ chance of active disease

Let us say Xh represents haemphilic affected chromosome. A normal father would have XY chromosome whereas a carrier mother will have XhX chromosomes. Hence, their male offspring will have either XhY or XY chromosomes make-up and their female offspring will have either XX (non-hemophilic daughter) chromosomes or XhX chromosomes (carrier daughter).

Hence, a male offspring has a 50% chance of active disease whereas a female offspring will either be normal or will be the carrier.

So, the correct answer is 'A male offspring has 50% chance of active disease'.