In Drosophila, the allele for normal grey body colour (G) is dominant to the ebony body (g). The following table summarises the results of several crosses: Cross Result Strain 1 × gg All Grey type Strain 2 × gg 1 Grey: 1 ebony Strain 3 × gg All ebony type Strain 4 × Gg 3 Grey: 1 ebony Which strains have the genotype Gg ?

Question

In Drosophila, the allele for normal grey body colour (G) is dominant to the ebony body (g). The following table summarises the results of several crosses: Cross Result Strain 1 × gg All Grey type Strain 2 × gg 1 Grey: 1 ebony Strain 3 × gg All ebony type Strain 4 × Gg 3 Grey: 1 ebony Which strains have the genotype Gg ? (A) 1 and 3 (B) 1 and 4 (C) 2 and 3 (D) 2 and 4

Tardigrade Admin · Accepted Answer

Strain 2 and 4 have the genotype Gg where grey body colour (G) is dominant to the ebony body colour (g). (Strain 2 × gg = Gg : gg = 1:1, and Strain 4 × Gg = GG : Gg : gg = 1:2:1).
Strain 1 will have genotype GG and Strain 3 will have genotype gg.

Cross	Result
Strain 1 × gg	All Grey type
Strain 2 × gg	1 Grey : 1 ebony
Strain 3 × gg	All ebony type
Strain 4 × Gg	3 Grey : 1 ebony

1 and 3

1 and 4

2 and 3

2 and 4

Strain 2 and 4 have the genotype Gg where grey body colour (G) is dominant to the ebony body colour (g). (Strain 2 × gg = Gg : gg = 1:1, and Strain 4 × Gg = GG : Gg : gg = 1:2:1). Strain 1 will have genotype GG and Strain 3 will have genotype gg.

Strain 2 and 4 have the genotype Gg where grey body colour (G) is dominant to the ebony body colour (g). (Strain 2 × gg = Gg : gg = 1:1, and Strain 4 × Gg = GG : Gg : gg = 1:2:1).
Strain 1 will have genotype GG and Strain 3 will have genotype gg.