There is a 75% chance that the offspring will have tall stems and a 25% chance that the offspring will have short stems.
It shows the parental phenotype, alleles, genotype, and possible gametes for heterozygous tall stems in pea plants.
The parental phenotype is tall stems, which is dominant.
The alleles for stem length are T for tall and t for short.
The parental genotype is Tt, which means that the parent plant has one copy of the T allele and one copy of the t allele.
The possible gametes for the parent plant are T and t.
When the parent plants produce gametes, the alleles for stem length segregate, meaning that each gamete receives one allele from each parent.
This results in two possible gametes for each parent plant: T and t.
When the gametes from the two parent plants fuse during fertilization, the offspring can inherit any combination of alleles.
This results in four possible genotypes for the offspring: TT, Tt, Tt, and tt.
Only the offspring with the TT genotype will have tall stems, because the T allele is dominant.
The offspring with the Tt genotype will also have tall stems, but they will be carriers for the short-stem allele.
The offspring with the tt genotype will have short stems.
Here is a Punnett square showing the possible genotypes and phenotypes of the offspring from a cross between two heterozygous tall-stemmed pea plants:
T t
T TT (tall) Tt (tall)
t Tt (tall) tt (short) .