Principles of Inheritance and Variation Question 144
144. A colour blind man marries a woman with normal sight who has no history of colour blindness in her family.
What is the probability of their grandson being colour blind?
[2015 RS]
145. An abnormal human baby with ’ $X X X$ ’ sex chromosomes was born due to :
[2015 RS]
Show Answer
Answer : c
Hints & Solution
(c) $XX \times X^{Y}$ Normal woman Colourblind man
| $(0^{\circ})$ | $X^{c}$ | $Y$ |
|---|---|---|
| $X$ | $XX^{c}$ | $XY$ |
| $X$ | $XX^{c}$ | $XY$ |
| The daughters of this couple will have normal eye sight but would be carrier. If one of the carrier daughter marries with normal eyed man, | ||
| {$XX^{c}$ Normal woman} |
{f86002e98-2173-43a0-a48a-0bffd842c68d}XY Normal man |
|
| :—: | :—: | :—: |
| (9) ${ }^{(0^{7})}$ | X | Y |
| $X$ | $XX$ | XY |
| $X^{c}$ | $XX^{c}$ | $X^{c} Y$ |
| Only $25 %$ grandson will show colourblindness. |
