Question

Assertion: Phenylketonuria is a recessive hereditary disease caused by the body’s failure to oxidise an amino acid phenylalanine to tyrosine, because of a defective enzyme.
Reason: It results in the presence of phenylpyruvate in the urine.

• A. Both the assertion and reason are true and the reason is the correct explanation for assertion.
• B. Both the assertion and reason are true and the reason is not the correct explanation for assertion.
• C. Assertion is true but the reason is false.
• D. Both the reason and assertion are false.

Answer 1

The correct option is A Both the assertion and reason are true and the reason is the correct explanation for assertion.

Phenylketonuria (PKU) is caused by decreased activity of phenylalanine hydroxylase (PAH), an enzyme that converts the amino acid phenylalanine to tyrosine, a precursor of several important hormones and skin, hair, and eye pigments. Levels of phenylpyruvate are normally very low in blood or urine. High levels of phenylpyruvic acid can be found in the urine of individuals with phenylketonuria