AP BIOLOGY

Detailed explanation-1: -Females are XX, and males are XY. Sex-linked traits are only found on the X chromosome, therefore the letters are placed as superscripts (above) the X chromosome. Therefore the genotype for the female fly is XrXr and the male is XRY.

Detailed explanation-2: -When a white eye Drosophila male(XrY) is crossed to a red eye female (XRXR), in the F2 generation all the females are red eyed and 50% males are white eyed.

Detailed explanation-3: -There are two different genotypes that code for the red-eyed phenotype (XRXR, XRXr) in females. Males have one genotype that codes for red eyes, XRY. Thus, the Red-eyed Male’s genotype can be determined from its phenotype. However, this is not possible in females.

Detailed explanation-4: -In a criss cross test, when a white eyed female(XrXr) is crossed to a red eye male(XRY), the F1 generation off spring had white eyed males while the female offspring had red eyes.