Question

You are examining a population of fruit flies. You cross 2 True Breeding lines, a Wildtype Male and a Female with Orange eyes and a Purple body in your P generation to produce an F1 generation. All of your F1 flies are Wildtype – assume you see the same results in your Reciprocal cross. Next, you cross two F1 flies to produce an F2 generation. You observe the following results among the offspring in your F2 generation: Purple body 472 Wild type 1403 Orange eyes 459 Orange eyes and Purple body 147 a) Based on these results, what were the Genotypes of the P generation flies you originally crossed?

Answer 1

Answer:

Each parent should be homozygous for each gene. The male has homozygous dominant alleles for both eyes and body phenotypes; and the female has homozygous recessive alleles for both eyes and body phenotypes.

Explanation:

The phenotypic ratio obtained in the F2 generation in the question corresponds to 9:3:3:1, which is characteristic of Mendel’s law of independent assortment after a dihybrid cross. This law states that different genes will be sorted and separated independently of one and other; and the predicted result of F2 phenotype after the genes are randomly sorted is the ratio mentioned above.