Apunnett square is drawn for parents, one of whom has phenylketonuria, a recessive genetic disorder, and the other who is a carrier of the disease. what are the odds of their children having phenylketonuria?

a.) 0%
b.) 25%
c.) 50%
d.) 75%
e.)100%

The correct answer would be option C. 50%

Explanation:

Phenylketonuria is an autosomal recessive genetic disorder. Phenylketonuria occurs if a person has two recessive alleles (p) for for PAH (phenylalanine hydroxylase) gene.

If the person has the heterozygous condition (Pp) for PAH gene, than he will be considered as a carrier for the disorder but if he has two dominant alleles (PP) of the disorder, he will be normal.

The child of parents, one with phenylketonuria (pp) and other who is carrier (Pp) is most likely to have 50% chances to having phenylketonuria.