question_answer

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.

(i) A woman has an X-linked condition on one of her X-chromosomes. This chromosome can be inherited by

A) Only grand children

B) Only sons

C) Only daughters     

D) Sons and daughter

Correct Answer: D

Solution :

[d] In the given problem, the woman has an X-linked condition and she can transmit the carrier allele to both her son and daughter. Out of the 4 offspring possible 25% of sons are diseased and 25% are normal. Similarly, 25% daughters normal and 25% are carriers.