_________ occurs when one X chromosome from a pair in a female's cell is silenced during development.
A) X chromosome inactivation
B) X chromosome activation
C) Crossing over
D) Nondisjunction

Question

Quizplus · Accepted Answer

X chromosome inactivation occurs during development in females, where one of the X chromosomes in each cell is randomly chosen to become inactive and form a dense structure called a Barr body. This is a mechanism to ensure that the gene dosage of X-linked genes is equal between males (who only have one X chromosome) and females (who have two). Choice B, X chromosome activation, does not occur during development as both X chromosomes are already active in females. Choice C, crossing over, is a process that occurs during meiosis where homologous chromosomes exchange genetic material. Choice D, nondisjunction, is a process where homologous chromosomes fail to separate during meiosis, resulting in abnormal numbers of chromosomes in gametes.

_________ Occurs When One X Chromosome from a Pair in a Female's