Question

In fruit flies, red eyes are dominant to sepia eyes. A researcher crosses two flies that are heterozygous for red eyes. They produce 734 offspring: 182 with sepia eyes and 552 with red eyes. About how many flies were heterozygous for red eyes?

A) 92
B) 270
C) 366
D) 552

Answer 1

To determine the number of flies heterozygous for red eyes, subtract the number of flies with the RR genotype from the total number of red-eyed flies. Hence, option (D) 552 is correct.

Step-by-step explanation:

To determine the number of flies heterozygous for red eyes, we need to calculate the number of flies with the genotype Rr. From the given data, we know that 182 flies have sepia eyes (rr genotype) and 552 flies have red eyes (RR or Rr genotype). Therefore, the number of flies with the genotype Rr can be calculated as:

Number of flies heterozygous for red eyes = Total number of red-eyed flies - Number of flies with the RR genotype

Number of flies heterozygous for red eyes = 552 - 0 (since all flies with red eyes can either have RR or Rr genotype)

Number of flies heterozygous for red eyes = 552