[Campbell Biology P.333] In Figure 14.15b, two parents who can taste PTC genotypes Tt have a... | Practice Question

In Figure 14.15b, two parents who can taste PTC genotypes Tt have a daughter who cannot genotype tt . This pattern, where an offspring exhibits a trait not shown by the parents, is a key indicator for what?

  • A: That the trait is caused by a dominant allele.
  • B: That the trait is caused by a recessive allele.
  • C: That the trait is polygenic.
  • D: That the parents are homozygous dominant.

Explanation

The tip for pedigree analysis in Figure 14.15b explains this exact scenario. When two parents who lack a trait have an offspring who expresses it, it demonstrates that the trait must be recessive. The parents are heterozygous carriers of the recessive allele.