Question

In pea plants, yellow seeds (y) are dominant and green seeds (y) are recessive. a pea plant with yellow seeds is crossed with a pea plant with green seeds. the resulting offspring have about equal numbers of yellow and green seeded plants. what are the genotypes of the parents?

Answer 1

The parental genotypes for the pea plants are Yy for the yellow-seeded parent and yy for the green-seeded parent, which explains the equal numbers of yellow and green seeded offspring.

Step-by-step explanation:

Understanding Parental Genotypes in Pea Plants

In pea plants, yellow seeds are dominant (Y) and green seeds are recessive (y). Given that a cross between a pea plant with yellow seeds and one with green seeds yields offspring with about an equal number of yellow and green seeds, we can deduce the genotypes of the parents. The parent with yellow seeds must be heterozygous (Yy) because they contribute both the dominant and recessive alleles. The green-seeded parent is homozygous recessive (yy) because green is the recessive trait and can only be expressed phenotypically when two recessive alleles are present.

To predict the genotypes and phenotypes of the offspring, a Punnett square analysis can be employed. In this scenario, the Punnett square would show 50% of the offspring having yellow seeds (Yy) and 50% with green seeds (yy), supporting the observation of equal numbers of yellow and green seeded plants among the offspring.

Answer 2

To get the result of having 50% of recessive phenotype (green seeds), it is necessary to have a homozygous recessive parent (yy) crossed with a heterozygous parent (Yy) in order to achieve the 50% Yy (yellow, dominant) and 50% (yy, green, recessive).

The Punnett square below illustrates the above result:
y y
Y Yy Yy
y yy yy

So we get 50% Yy(heterogous, yellow dominant) and 50% yy (homozygous recessive, green).