A white-eyed female Drosophila is crossed with a red-eyed male. Which of the following is not correct about this cross?

• In this classic experiment studying X-linked inheritance in Drosophila, the eye color gene resides on the X chromosome. Red eye color (R) is dominant over white eye color (r). Since the female has two X chromosomes (one with r and one without) and the male has one X chromosome with R, the following happens:

✏️F₁ generation:
-Female offspring inherit one X chromosome with R from the father and one with r from the mother. They are heterozygous (Rr) and express the dominant red eye color (not homozygous dominant RR).
-Male offspring inherit only the mother's X chromosome with r. They are hemizygous (r) and express the recessive white eye color.

✏️F₂ generation:
-When the F₁ females (Rr) are crossed among themselves, their sex cells can be: R and r.
-Males (r) only produce r sperm.

✏️Possible offspring genotypes and phenotypes are:
-RR and Rr females: red eyes (3:1 ratio)
-rr males: white eyes (1:1 ratio)

• Therefore, the F₁ generation will not be entirely red-eyed, making Option A incorrect. All other options are true:
-B. F₁ shows a 1:1 ratio for red and white eyes (females: red, males: white).
-C. F₂ ratio is 3:1 red: white (3 red females + 1 red male : 1 white male).
-D. In F₂, both males and females show a 1:1 ratio for eye color (males remain hemizygous, females have a 1:1 chance of inheriting R or r).

🔴Related Terminologies::
-X-linked inheritance: Inheritance patterns determined by genes on the X chromosome.
-Dominant/recessive alleles: Alleles where one masks the effect of the other in heterozygous individuals.
-Heterozygous/hemizygous: Having two/one different alleles for a gene, respectively.
-Meiosis: Cell division process producing gametes with half the genetic material.