Answer:
The genotype of a fly can be determined gray bodied is dominant over black body flies. The possible genotype of a fly is either YY or Yy.
Step-by-step explanation:
The genotype of a gray bodied fly can be determined with the help of punnett square. The gray bodied fly is crossed with black bodied fly, the original genotype of the fly can be determined. This type of cross is known as test cross.
If the cross results in the formation of all gray bodied progeny, the fly is homozygous dominant with the genotype YY. The cross results in the mixture of progeny with gray and black body , then the genotype of a fly is heterozygous dominant Yy.
Thus, the genotype of a fly can be determined by the test cross. The fly may have genotype either YY or Yy.