Two true-breeding populations of fruit flies, one with red, oval eyes and the other with white, round eyes, were crossed. All F1 offspring exhibited red, oval eyes. If 1,000 F2 offspring were produced from the mating, how many would you expect to exhibit red, round eyes?

The question indicates that two true-breeding populations of fruit flies, one with red, oval eyes (which we can denote as RR OO for the sake of argument, with "R" indicating the dominant red eye color allele and "O" for the dominant oval eye shape allele) and the other with white, round eyes (which we can denote as rr oo, with "r" for the recessive white eye color allele and "o" for the recessive round eye shape allele), were crossed.

Since the F1 offspring all have red, oval eyes, it means that the red eye color (R) and the oval eye shape (O) are dominant traits over white eye color (r) and round eye shape (o) respectively.

The F1 generation, therefore, will all be heterozygous for both traits (Rr Oo).

To find the phenotype of the F2 offspring when the F1 generation is crossed amongst themselves, you use a Punnett square to determine the genotypic ratios.

A two-trait Punnett square (dihybrid cross) with heterozygous parents for both traits (Rr Oo x Rr Oo) will result in the following genotype ratios for the offspring:

- 9/16 will have the dominant traits for both (red, oval), - 3/16 will have the dominant trait for the first gene and the recessive trait for the second (red, round), - 3/16 will have the recessive trait for the first gene and the dominant trait for the second (white, oval), - 1/16 will have the recessive traits for both (white, round).

We are interested in the red, round eyes phenotype, which occurs with a 3/16 probability. So, to know how many out of 1,000 would exhibit red, round eyes, you multiply 1,000 by this probability:

1,000 F2 offspring * 3/16 = 187.5

Since you can't have half a fruit fly, you would expect approximately 188 F2 offspring to have red, round eyes.