Question

r= red eyes; r= white eyes - parents are a homozygous white eyed female and a red eyed male
in fruit flies, the color of the eyes is sex linked (on the x chromosome). a cross of the flies in the image will produce
(image of a punnett square with x^r, x^r at the top, x^r and y on the left)
options:
○ a 0% of the females with white eyes, 50% of the males with white eyes.
○ b 100% of the females with red eyes, 100% of the males with white eyes.
○ c 0% white eyed flies
○ d 50% red eyed flies

Explanation:

Step1: Determine Parent Genotypes

Female (homozygous white - eyed): \(X^{r}X^{r}\) (so gametes are \(X^{r}\), \(X^{r}\)). Male (red - eyed): \(X^{R}Y\) (gametes: \(X^{R}\), \(Y\)).

Step2: Complete Punnett Square

• Top - left: \(X^{R}X^{r}\) (female, red eyes, since \(R\) is dominant).
• Top - right: \(X^{R}X^{r}\) (female, red eyes).
• Bottom - left: \(X^{r}Y\) (male, white eyes).
• Bottom - right: \(X^{r}Y\) (male, white eyes).

Step3: Analyze Offspring

• Females: Both \(X^{R}X^{r}\), so 100% red - eyed.
• Males: Both \(X^{r}Y\), so 100% white - eyed.

Answer:

b. 100% of the females with red eyes, 100% of the males with white eyes.