In pea plants, height is controlled by a single gene and the tall allele (T) is dominant to the short allele (t). You find a tall pea plant in your yard and cross it with a short pea plant. It gives rise to 43 tall offspring and 35 short offspring. What is the genotype of the tall parent plant?

Question

In pea plants, height is controlled by a single gene and the tall allele (T) is dominant to the short allele (t). You find a tall pea plant in your yard and cross it with a short pea plant. It gives rise to 43 tall offspring and 35 short offspring. What is the genotype of the tall parent plant?

TT
Tt
tt

Answer 1

Since height is controlled by a single gene and the tall allele (T) is dominant to the short allele (t), the tall parent plant could either be homozygous dominant (TT) or heterozygous (Tt).

From the ratio of the offspring (43 tall and 35 short), we can infer that the tall parent plant must have been heterozygous (Tt) because if it were homozygous dominant (TT), all the offspring would be tall.

Therefore, the genotype of the tall parent plant is Tt.