Question

Which of the following statements is true regarding Drosophila?

A) The ratio of autosomes to fly Y and X chromosomes determines fly sex.
B) The ratio of X to Y chromosomes determines fly sex.
C) The Y chromosome determines male flies.
D) The Y chromosome plays no role on fly sex determination but does contain genes for fly
reproduction.

Answer 1

Drosophila sex is determined by the ratio of autosomes to fly Y and X chromosomes.

Step-by-step explanation:

The statement that is true regarding Drosophila is:

A) The ratio of autosomes to fly Y and X chromosomes determines fly sex.

In Drosophila, the sex is determined by a series of splicing events in sex determination genes on a cell-by-cell basis without involvement of sex hormones. The primary sex-determination gene is called Sex lethal (Sx), which is transcribed only when the X/A ratio (the X chromosome-to-autosome ratio) equals or exceeds 1. As females have two X chromosomes and males have one, Sxl is transcribed only in females.