Which one of the following is a dominant trait?

Assertion: Phenylketonuria is a recessive hereditary disease caused by the body's failure to oxidize the amino acid phenylalanine to tyrosine due to a defective enzyme.
Reason: It results in the presence of phenylalanine acid in urine.

The given chart shows a pedigree analysis. What does it represent?

Choose the incorrect statement for haemophilia.

The gene for haemophilia is located on the $X$ chromosome. Hence,it is normally impossible for a:

$A$ person whose father is colourblind marries a lady whose mother is the daughter of a colourblind man. Their children will be: