Question

A woman with two genes (one on each X-chromosome) for haemophilia and one gene for colour blindness on the X-chromosome marries a normal man. How will the progeny be?

• A. All sons and daughters are haemophilic and colorblind
• B. Haemophilic and colorblind daughters
• C. 50% haemophilic, colorblind sons and 50% haemophilic sons
• D. 50% haemophilic daughters and 50% colorblind daughters

Answer 1

The correct option is C 50% haemophilic, colorblind sons and 50% haemophilic sons

Haemophilia and colour blindness both are recessive X-linked traits. They express in males when present in single copy (heterozygous) but in females, they express only when present in homozygous condition.