Question

Imagine you are performing a cross involving seed color in garden pea plants. What F₁ offspring would you expect if you cross true-breeding parents with green seeds and yellow seeds? Yellow seed color is dominant over green.

a) All green seeds
b) All yellow seeds
c) 50% green, 50% yellow seeds
d) 75% green, 25% yellow seeds

Answer 1

When crossing true-breeding green-seeded plants with true-breeding yellow-seeded plants, all F1 offspring will have yellow seeds because yellow is the dominant trait. Each F1 plant will have the genotype 'Yy', corresponding to a yellow phenotype.

Step-by-step explanation:

When performing a cross involving seed color in garden pea plants with one parent having true-breeding green seeds (recessive) and the other parent having true-breeding yellow seeds (dominant), the F1 generation will all have yellow seeds. The reason is that yellow seed color is a dominant trait over green. Using a Punnett square, we can visualize this cross by assigning 'Y' to represent the dominant yellow allele and 'y' to represent the recessive green allele. The parent with yellow seeds has the genotype 'YY' and the parent with green seeds has the genotype 'yy'. The result is that all of the F1 offspring will have the genotype 'Yy', expressing the yellow phenotype because the presence of a single 'Y' allele is sufficient to express the dominant trait.

The correct answer to what F1 offspring we would expect is b) 100 percent yellow seeds. There would be no green seeds in the first filial generation because the yellow trait is dominant and thus masks the expression of the green trait in the heterozygous F1 plants.