Principles of Inheritance and Variation Question 174
174. A normal woman, whose father was colourblind is married to a normal man. The sons would be
[2004]
(a) $75 \%$ colour-blind
(b) $50 \%$ color-blind
(c) all normal
(d) all colour-blind
Show Answer
Answer : b
Hints & Solution
(b) Normal woman with colour blind father would be a carrier.
| Woman $(\mathbf{X}^{c} \mathbf{X})$ | $X$ | Normal man (XY) | ||
|---|---|---|---|---|
| Progeny | $\underset{\substack{\text{ normal } \\ \text{ but carrier } \\ \text{ daughter }}}{X^{c} X}$ | $\underset{\substack{\text{ normal } \\ \text{ daughter }}}{XX}$ | $\underset{\substack{\text{ colour blind } \\ \text{ son }}}{X^{C} Y}$ | $\underset{\substack{\text{ normal } \\ \text{ son }}}{X Y}$ |
$50 \%$ of the sons would be colour blind.
