a normal vission female whose father is colour blind marries a normal vision male.what would be the probability of her son's and daughters to be colour blind?
(A)-25% son's colour blind and all daughter with phenotypically normal vision ,(B)- 50% son's colour blind and 50% daughter colour blind,,(C)- 50% sons colour blind and 50%daughter colour blind,,(C)-all son's normal and 50% colour blind daughter
Answers
The correct answer is (A).It has been explained below using a genetic representation.
Colour blindness is a X-linked recessive trait and hence a female(having two X-chromosomes) can either be a carrier or an affected one,on the other hand since males have only one X-chromosome they can either be a normal male or a colour blind one.
A normal vision female having a colour blind father itself means that she is a carrier of the trait since she gets one X-chromosome from her father and one from her mother.When this female marries a normal vision male, she alone passes on the trait to the next generation.Since her husband is of normal vision, none of the daughters will be colour blind but the sons who get the affected X-chromosome from their mother will be colour blind.However, the sons who get the unaffected X-chromosome will be normal again.
