Q. A woman with two genes (one on each X-chromosome) for haemophilia and one gene for colour blindness on the X-chromosomes marries a normal man. How will the progeny be?
Solution:
Haemophillia 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.
Results:
(a) sons are colourblind and haemophilic.
(b) sons are haemophilic only.
(c) daughters are carrier for colour blindness and haemophilia.
(d) daughters are carrier for haemophilia only.
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