What process results from the failure of chromosome pairs to separate during meiosis?

The correct answer is nondisjunction, which refers to the failure of homologous chromosomes to separate properly during meiosis. This failure can occur during either meiosis I or meiosis II, leading to gametes that contain an abnormal number of chromosomes. When these gametes fuse with normal gametes during fertilization, the resulting zygote may have an imbalance in chromosome number.

Such an imbalance can lead to conditions known as aneuploidy, where there is an atypical number of chromosomes. While both nondisjunction and aneuploidy involve abnormal chromosome numbers, nondisjunction specifically describes the process that causes this issue. This distinction is important in understanding how chromosomal abnormalities arise.

Inversion, on the other hand, refers to a chromosome segment being flipped in orientation, which does not relate to chromosome separation failure. Point mutations involve changes to a single nucleotide in the DNA sequence and are not linked to chromosomal separation processes. Understanding these terms helps clarify how chromosomal arrangements and numbers can change due to different mechanisms.