KCET 2015 Biology Solved Paper

Phenylketonuria is an inborn error of metabolism. It is an autosomal recessive disorder in which the homozygous recessive individual lacks the enzyme phenylalanine hydroxylase needed to change phenylalanine (amino acid) to tyrosine (amino acid) in the liver. Lack of the enzyme is due to abnormal autosomal recessive gene on chromosome 12. The defective gene influences many characters, so it is an example of pleiotropic gene.