What does nondisjunction most directly result in?

Nondisjunction is a key concept in genetics that refers to the failure of homologous chromosomes or sister chromatids to separate properly during meiosis or mitosis. This improper segregation can lead to gametes that have an abnormal number of chromosomes. When such gametes fuse during fertilization, the resulting zygote will also have an abnormal number of chromosomes, which may lead to conditions such as Down syndrome, Turner syndrome, and Klinefelter syndrome.

The correct answer highlights how nondisjunction specifically results in either an excess of chromosomes (trisomy) or a deficit (monosomy). For example, in Down syndrome, there is an extra copy of chromosome 21, resulting from nondisjunction during gamete formation. Understanding this mechanism is crucial in the study of genetic disorders and inheritance patterns.

Other options do not accurately reflect the consequences of nondisjunction. Increased genetic diversity refers to the variation seen in genes within populations, not a direct result of nondisjunction. Uniformity in genetic traits suggests a consistent genetic makeup, which contrasts sharply with the irregularities caused by nondisjunction. Dominance of certain alleles pertains to the expression of genes rather than chromosome number and separation issues. Thus, the link between nondisjunction