[Campbell Biology P.334] Why are individuals who are heterozygous Aa for a recessively inher... | Practice Question

Why are individuals who are heterozygous Aa for a recessively inherited disorder typically phenotypically normal?

  • A: Because the recessive allele is masked by the process of epistasis.
  • B: Because one copy of the normal allele produces a sufficient amount of the specific protein.
  • C: Because they cannot pass the recessive allele to their offspring.
  • D: Because the environment prevents the expression of the recessive allele.

Explanation

The text explicitly states that in recessive disorders, 'heterozygotes Aa typically have the normal phenotype because one copy of the normal allele A produces a sufficient amount of the specific protein.' The presence of one functional allele is enough to prevent the disease phenotype from showing.