Two tall plants were crossed and all the F1 plants were tall. when the F1 plants were selfed, some of the F2 plants were tall while others were short what are the possible genotypes of the original plants ?
The possible genotypes of the original plants could be TT and Tt.
In this scenario, we are crossing two tall plants, which means they both have the allele for tall height (T). When these two plants are crossed, their offspring in the F1 generation will all be tall because they inherit a copy of the tall allele from each parent (Tt).
Now, when the F1 plants are selfed, meaning they are allowed to reproduce with each other, the resulting F2 generation shows a mixture of tall and short plants. This indicates that there is a presence of a recessive allele for short height (t).
To have a mixture of tall and short plants in the F2 generation, the original plants must have been heterozygous for the height trait. This means that one parent carried two copies of the tall allele (TT), while the other parent carried one copy of the tall allele and one copy of the short allele (Tt). When these plants are crossed, there is a 25% chance of producing offspring with the genotype TT (tall), a 50% chance of producing offspring with the genotype Tt (tall), and a 25% chance of producing offspring with the genotype tt (short).
Therefore, the possible genotypes of the original plants are TT and Tt, where TT represents a homozygous tall genotype and Tt represents a heterozygous tall genotype.