During development,an XX female embryo will form one of the X chromosomes in each cell into a Barr body.This usually occurs
A) about two weeks after zygote formation.
B) by the end of the first trimester.
C) at the 16-cell stage.
D) in the X that is the most recessive.
E) in the X that is the least recessive.

Question

Quizplus · Accepted Answer

The formation of a Barr body, which is the inactivation of one of the X chromosomes in each cell of a female embryo, typically occurs about two weeks after zygote formation. This process ensures that females, like males, have one functional copy of the X chromosome in each body cell.

During Development,an XX Female Embryo Will Form One of the X