In man,albinism is due to the non-synthesis of melanin in the absence of:

Assertion: Persons suffering from haemophilia fail to produce blood clotting factor $VIII$.
Reason: Prothrombin producing platelets in such persons are found in very low concentration.

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:

$A$ color-blind man marries a woman with normal vision,whose family has no history of color blindness. What is the probability that their daughter's children (grandsons and granddaughters) will be color-blind?

$A$ color-blind girl is rarely born. This occurs only when:

Which one is a sex-linked disease?