Alkaptonuria is caused due to

$A$ woman has a haemophilic son and three normal children. Her genotype and that of her husband with respect to this gene would be

$A$ normal woman,whose father was colour-blind,is married to a normal man. The sons would be

$A$ 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?

Which of the following is ineffective against antibiotics?

Which one of the following disorders is caused by the substitution of Glutamic acid (Glu) by Valine (Val) at the sixth position of the beta globin chain of the haemoglobin molecule?