Question

if pinkys sister is able to taste ptc and we know that both of her parents are heterozygous for this characteristic, what must her genotype be?
tt or tt
tt or tt

Explanation:

Step1: Define alleles

Let T be the dominant allele for tasting PTC and t be the recessive allele.

Step2: Set up Punnett - square

Parents are Tt x Tt. The possible gametes from each parent are T and t. The Punnett - square has the following combinations: TT, Tt, Tt, tt.

Step3: Determine phenotype - genotype relationship

The ability to taste PTC is a dominant - trait. So, individuals with genotypes TT or Tt can taste PTC.

Answer:

B. TT or Tt