An animal has a diploid chromosome number of 12. An egg cell of that animal has 5 chromosomes. The most probable explanation is
A) normal mitosis.
B) normal meiosis.
C) nondisjunction in meiosis I.
D) nondisjunction in meiosis I or II.
E) nondisjunction in mitosis.

Question

Quizplus · Accepted Answer

If an egg cell of this animal has only 5 chromosomes, it suggests that nondisjunction occurred during meiosis, resulting in aneuploidy of either the first or second division. Therefore, the most probable explanation is either nondisjunction in meiosis I or meiosis II, making choice D the best answer.

An Animal Has a Diploid Chromosome Number of 12