Q157 / 180 · AIIMS 2019 (25 May) · Zoology

Assertion : Phenylketonuria, haemophilia and sickle cell anaemia are genetic disorders. Reason : In phenylketonuria, the person lacks an enzyme for the conversion of phenylalanine into tyrosine.

  • A
    If both assertion and reason are true and reason is the correct explanation of assertion.
  • Correct answer
    B
    If both assertion and reason are true but reason is not the correct explanation of assertion.
  • C
    If assertion is true but reason is false.
  • D
    If both assertion and reason are false.

Solution

Phenylketonuria is inborn error of metabolism inherited as the autosomal recessive trait. The affected individual lacks an enzyme that converts the amino acid phenylalanine into tyrosine. As a result of this phenylalanine is accumulated and converted into phenylpyruvic acid and other derivatives. Accumulation of these in brain results in mental retardation. These are also excreted through urine because of its poor absorption by kidney.

Hence, the correct answer is option: 'B'.

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