If several pea plants with the genotype t tyy are crossed with pea plants with the genotype ttyy, what percentage of the offspring will be expected to have the t tyy allele combination?

To determine the results, lets make a punnet square to check for the probabilities.

           Ty          Ty          t y           t y

TY     TTYy        TTYy      TtYy      TtYy

Ty      TTyy         TTyy      Ttyy       Ttyy

TY      TTYy        TTYy      TtYy      TtYy

Ty       TTyy         TTyy      Ttyy       Ttyy

4 out of 16 pea plants will have the probability of having the genotype TTYy. There will be a 25% chance that the offsprings will have the genotype TTYy.