Final answer:
The most probable genotype of each parent would be Gg for the gray-seeded parent and gg for the white-seeded parent. The genotypic ratio in the progeny would be 1 GG : 2 Gg : 1 gg, and the phenotypic ratio would be 3 gray : 1 white.
Step-by-step explanation:
In this case, we are told that gray seed color is dominant to white in peas. When Mendel crossed plants with gray seeds, he obtained 250 gray and 80 white progeny. From this information, we can determine the most probable genotypes of the parents.
If gray is dominant, then the gray seeds could be represented by the genotype GG or Gg. Since the gray parent produced both gray and white offspring, it must be heterozygous (Gg), because a homozygous gray parent (GG) would only produce gray offspring.
Therefore, the most probable genotype of each parent would be Gg for the gray-seeded parent and gg for the white-seeded parent.
In terms of genotypic and phenotypic ratios in the progeny of such a cross, we can consider the possible combinations of alleles from the parents.
The genotype of the gray-seeded parent (Gg) can produce two types of gametes: G and g. The genotype of the white-seeded parent (gg) can only produce one type of gamete: g.
When we combine the gametes from the parents, we can create four possible genotypes in the progeny: GG, Gg, Gg, and gg. However, since gray (G) is dominant, only the genotypes GG, Gg, and Gg will express the gray seed color phenotype.
Using the Punnett square method, we can calculate the expected genotypic and phenotypic ratios in the progeny:
Genotypic ratio: 1 GG : 2 Gg : 1 gg
Phenotypic ratio: 3 gray : 1 white