Final answer:
When a TT plant is crossed with a Tt plant, the F2 generation offspring have a 3:1 phenotypic ratio for dominant to recessive traits, with 1/4 being homozygous recessive (tt) and thus expressing the recessive trait.
Step-by-step explanation:
If one of the plants used in the F1 cross had TT alleles and was combined with a plant with Tt alleles, the trait controlled by the recessive allele would potentially be produced in the resulting F2 generation. The combination of these genotypes in the parent plants suggests Mendelian inheritance patterns and a Punnett square analysis can reveal the possible genotypic and phenotypic outcomes for the F2 generation. Since we are dealing with T (tall) as the dominant trait and t (short) as the recessive trait, any offspring with at least one T allele will display the tall phenotype. Only offspring with tt genotype will display the short phenotype characteristic of the recessive allele.
According to Mendelian genetics, when a TT plant is crossed with a Tt plant, the F1 generation will all be phenotypically tall since both genotypes express the tall trait (TT and Tt). However, the genotypic makeup of the F2 generation resulting from self-crossing the F1 offspring will exhibit a 3:1 ratio of dominant to recessive. Specifically, the genotypic ratio for the F2 generation is expected to be 1 TT: 2 Tt: 1 tt, meaning that the trait for the recessive allele (shortness) would be expressed phenotypically in the tt plants which would represent 1/4 of the offspring, confirming that the recessive trait was indeed passed down from the original parents.