Question

In peas, the trait for tall plants is dominant (T) and the trait for short plants is recessive (t). The trait for yellow seeds is dominant (Y) and the trait for green seeds is recessive (y). A cross between two plants results in 292 tall yellow plants and 103 short green plants.

a. What are the most likely genotypes of the parents? (Hint, think of the genotypes for plant height and seed color separately, then combine the results)

Answer 1

both are heterozygous (TtYy)

Step-by-step explanation:

The two parents are most likely heteozygous for both trait with genotypes TtYy respectively.

According to Mendelian cross involving two heterozygous individuals in a dominant/recessive trait, the alleles will segregate and randomly unite to give a phenotypic ratio of 3:1 dominant to recessive trait.

292:103 can be considered to be roughly equivalent to a ratio of 3:1.

Assuming this is true for the for the plant's height:

Tt x Tt: TT (tall), 2 Tt (tall), tt (short).

The ratio of tall to short = 3:1

Assuming it is also true for seed color:

Yy x Yy: YY (yellow), 2 Yy (yellow), yy (green)

Ratio of yellow to green = 3:1

It thus means that the parents are heterozygous for both traits with genotype TtYy.