Polydactyly in humans is caused by a/an:

$A$ girl of normal vision whose father was colourblind marries a man of normal vision whose father was also colourblind. What percentage of their sons would be colourblind?

In the $\beta$-globin chain of haemoglobin of an individual,if the sixth amino acid,Glutamic acid (Glu),is replaced by Valine (Val),then the individual will be suffering from:

If an albino man marries a normal woman and $50$ offspring are albino and $50$ are normal,the woman is:

Given that $X^h$ is the chromosome with the gene for haemophilia and $X$ is the chromosome with the normal gene. Which of the following individuals will act as a carrier for haemophilia?

$A$ woman with normal vision, whose father was colorblind, marries a colorblind man. If the fourth child of this couple is a boy, then he will be: