If a human zygote has either 45 or 47 chromosomes it was caused by nondisjunction.

Question

Quizplus · Accepted Answer

Nondisjunction is the failure of chromosomes to separate properly during cell division, leading to an abnormal number of chromosomes in the resulting cells. If this occurs in the process of fertilization, it can result in a zygote (an embryo at its earliest stage) with either 45 or 47 chromosomes instead of the typical 46. Therefore, option A is correct.

If a Human Zygote Has Either 45 or 47 Chromosomes