Question

In fruit flies, the grey body colour is dominant to the black, and long wings are dominant to short. On the crossing of a grey, short-winged fly and a black, long-winged fly, produces 25 percent grey, long wing, 25 percent grey, short wing, 25 percent black, short wing, and 25 percent black, long wing, the genotypes of the parental flies is

• A. Ggll and GgLl
• B. Ggll and ggLl
• C. GGll and ggLl
• D. GGll and GgLl
• E. Ggll and ggLL

Answer 1

The correct option is B Ggll and ggLl

According to the question, parents are gray, short-winged fly and a black, long-winged fly. Since gray body color is dominant over black and long wings are dominant over short, the parents are homozygous for these recessive traits. The genotype of a parent with gray, short-wing is Ggll and that of black, the long-winged fly is ggLl. The ratio of black and gray progeny is 1:1 (25 percent gray, long wing and 25 percent gray, short wing: 25 percent black, short wing; and 25 percent black, long wing). Likewise, the ratio of progeny with short and long wings is also 1:1. A cross between heterozygous dominant and homozygous recessive gives 1 dominant: 1 recessive progeny. This means the parent fly with gray, short-wings is heterozygous for the body color and the parent fly with black, long-wings is heterozygous for wing length. Therefore, the genotype of the parent with gray, short-wing is Ggll and that of black, the long-winged fly is ggLl. Thus, the correct answer is option B.