Recessive characters are expressed
Only when they are present on $X$ chromosomes of male
Only when they are present on $X$ chromosomes of female
On any autosome
On both the chromosomes of female
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 ?
Colour blindness in man is
Phenylketonuria is a genetic disorder due to a defect in metabolism of the following.
A woman with two genes for haemophillia and one gene for colourblindness on one of the $X$ chromosomes marries a normal man. How will the progeny be
Persons who are colour blind cannot distinguish