Two pea plants are mated that are heterozygous for height where the tall (T )trait is dominant to short plants (t),and flower color where white flower color ( p)is recessive to purple flower color (P).What is the ratio that one would expect in their offspring?
A) 3:1
B) 1:1
C) 1:1:1:1
D) 9:3:3:1

Question

Quizplus · Accepted Answer

For each trait, we can use Punnett squares to determine the possible genotypes and phenotypes of the offspring.

For height:

|    | T  | t  |
|----|---|---|
| T  | TT | Tt |
| t  | Tt | tt |

There are 3 possible genotypes: TT, Tt, and tt. However, since T is dominant, the TT and Tt genotypes will result in tall plants, while only the tt genotype will result in a short plant. Therefore, the phenotype ratio is 3:1 tall:short.

For flower color:

|    | P  | p  |
|----|---|---|
| P  | PP | Pp |
| p  | Pp | pp |

There are 3 possible genotypes: PP, Pp, and pp. However, since P is dominant, only the PP and Pp genotypes will result in purple flowers, while the pp genotype will result in white flowers. Therefore, the phenotype ratio is 3:1 purple:white.

To determine the ratio of both traits together, we can multiply the ratios:

3 (Tall) : 1 (Short) x 3 (Purple) : 1 (White)

Simplifying this ratio gives us a 9:3:3:1 ratio of TTPP, TTPp, TTpp/TtPP, TtPp, Ttpp, ttPP/ttPp, ttpp. This means that we would expect 9 plants that are tall and have purple flowers, 3 that are tall and have white flowers, 3 that are short and have purple flowers, and 1 that is short and has white flowers.

Two Pea Plants Are Mated That Are Heterozygous for Height