Question

Pea plants are tall if they have the genotype TT or Tt, and they are short if they have genotype tt. A tall plant is mated with a short plant. Which outcome below would indicate that the tall parent plant was heterozygous?

Answer 1

1:1 phenotypic ratio of tall : short plants

Step-by-step explanation:

If the tall parent is homozygous (TT), on mating with a short plant:

TT X tt :

T T

t Tt Tt

t Tt Tt

All plants in next progeny will be tall

If the tall parent is heterozygous (Tt), on mating with a short plant:

Tt X tt :

T t

t Tt tt

t Tt tt

Half of the plants in next progeny will be tall (Tt), other half will be short (tt) .

Hence, 1:1 phenotypic ratio of tall : short plants would indicate that the tall parent plant was heterozygous.