Q. A colour-blind man marries a woman who is carrier for haemophilia. Which of the following is true for their progenies?
NTA AbhyasNTA Abhyas 2022
Solution:
Genotype of Male is $X_{c}Y$ and Genotype of Female is $X_{h}X$ .
The genotypes of their children will be
$X_{c}$ $Y$ $X_{h}$ $X_{c}X_{h}$ $X_{h}Y$ $X$ $X_{c}X$ $XY$
Their children $X_{c}X$ (daughter carrier for colourblindness),
$X_{c}X_{h}$ (daughter carrier for colourblindness and haemophilia), XY (normal son), $X_{h}Y$ (haemophiliac son)
Thus, 25% of their children will carry the genes for both haemophilia and colour-blindness $X_{c}X_{h,}$ 25% of their children will carry the gene only for haemophilia $X_{h}Y and \, $ 25% of the progenies carry only the gene for colour-blindness $X_{c}X$
| $X_{c}$ | $Y$ | |
| $X_{h}$ | $X_{c}X_{h}$ | $X_{h}Y$ |
| $X$ | $X_{c}X$ | $XY$ |