| Direction Read the following and answer the questions from given below |
| Colour blindness is a sex-linked recessive disorder, which results in defect in either red or green cone of eye. It does not mean not seeing any colour at all, infact it leads to the failure in discrimination between red and green colour. The gene for colour blindness is present on X-chromosome. It is present mostly in males \[({{X}^{C}}Y)\] because of the presence of only one X-chromosome as compared to two chromosomes in females. A heterozygous female has normal vision, but is a carrier and passes on the disorder to some of her sons. A woman has an X-linked condition on one of her X-chromosomes. This chromosome can be inherited by |
| (v) Assertion [A] When a colourblind woman marries a normal man all her sons show colour blindness and all her daughters have normal vision. |
| Reason [R] When these daughters marry a colourblind man, 75% of their sons as well as daughters are colourblind. |
A) Both A and R are true and R is the correct explanation of A
B) Both A and R are true, but R is not the correct explanation of A
C) A is true, but R is false
D) A is false, but R is true
Correct Answer: C
Solution :
[c] A is true, but R is false. When colourblind woman marries a normal man, all her sons show colour blindness and all her daughters have normal vision. But when these daughters marry a colourblind man, 50% of their sons as well as daughters are colourblind.
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