Which disease is caused by the deficiency of factor $VIII$?

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:

$A$ normal woman,whose father was colorblind,marries a normal man. What will be the status of their sons?

If a father and son are both defective in red-green colour vision,is it likely that the son inherited the trait from his father? Comment.

The most common type of haemophilia results from the congenital absence of

Select the incorrect match regarding the symbols used in Pedigree analysis: