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

(ii) Anish is having colour blindness and married to Sheela, who is not colourblind. What is the chance that their son will have the disease?

A) 100%                           

B) 50%

C) 25%                 

D) 0%

Correct Answer: D

Solution :

[d] If Sheela is normal then chances of their son being colourblind are 0%. It can be represented as follows Case II Thus, there are 0% chances of their son being colourblind.