Question

If nondisjunction of X-chromosomes occurs at a rate of 2% in a certain population of Drosophila, approximately how many white-eyed males would you expect to see from 1000 fertilized eggs resulting from breeding a true breeding red-eyed female with a white- eyed male?

Answer 1

In a cross between a white-eyed male and a female heterozygous for red eye color, approximately 50% of the offspring would have red eyes and approximately 50% would have white eyes.

Step-by-step explanation:

In a cross between a white-eyed male and a female heterozygous for red eye color, the offspring ratio would depend on the genotype of the female. In this case, the female is heterozygous for red eye color, which means she has one dominant allele (red eye) and one recessive allele (white eye). The genotype of the female can be represented as XW X". The genotype of the white-eyed male is XY, as in Drosophila, males have one X chromosome and one Y chromosome.

When crossing the white-eyed male with the heterozygous red-eyed female, the possible genotypes for the offspring are XW XW, XW X", X" X", and XY. The red-eye allele is dominant (XW), while the white-eye allele is recessive (X").

The ratio of offspring can be determined by using a Punnett square. There are four possible combinations in the F1 generation: XW XW, XW X", X" X", and XY. From these combinations, you can determine that approximately 50% of the offspring will have red eyes (XW XW or XW X") and approximately 50% will have white eyes (X" X" or XY).