Question

Yellow-bodied, white-eyed females in Drosophila have the following genotype

• A. yyww
• B. y⁺yw⁺w
• C. y⁺y⁺w⁺w⁺
• D. ${\mathrm{yyw}}^{+}{w}^{+}$

Answer 1

The correct option is A yyww

In Drosophila, the genes controlling body colour and eye colour are located on the X chromosome. This was experimentally discovered by T. H. Morgan.

Mutant phenotypes are recessive traits and hence are denoted with small letters. The wild types (normal phenotype) are dominant and denoted with the same alphabet used for mutants but with a (+) sign used as the superscript.

The allele responsible for red eye colour (wild type/dominant phenotype) is $w^{+}$ and the allele responsible for white eye colour (mutant/recessive phenotype) is represented by w.
The allele responsible for brown body colour (wild type/ normal phenotype) is represented by $y^{+}$ and that responsible for yellow body colour (mutant/recessive phenotype) is represented by y.

Since the yellow colour of the body and the white colour of the eyes are recessive phenotypes, these are expressed only in homozygous conditions.

Therefore, the genotype of yellow-bodied, white-eyed females in Drosophila is yyww.