You do a cross between two true-breeding strains of zucchini. One has green fruit end the other has yellow fruit. The Fl plants are ell green, but when these are crossed, the F2 plants consist of 9 green : 7 yellow. Explain this result. What a. were the genotypes of the two parental strains? b. Indicate the phenotypes, with frequencies, of the progeny of a testcross of the Fl plant.

a) GG and gg

b) GG: Gg: gg

1: 2: 1

Phenotype ration

Green : yellow

3:1

Explanation:

As mentioned the two true breeding strains of zucchini were crossed.

True breeding means they must be homozygous for their genotype structure.

Let green fruit allele be represented by "G" and yellow fruit allele be represented by "g"

In first cross all green offspring were produced, thus it is clear that green fruit allele is dominant over yellow color fruit.

a) Genotype of the parents is

GG and gg

GG * gg

Gg, Gg, Gg, Gg

b) F1 cross will be between Gg * Gg

Offspring produced - GG, Gg, Gg, gg

Hence

Genotype ratio

GG: Gg: gg

1: 2: 1

Phenotype ration

Green : yellow

3:1