What is a significant consequence of nondisjunction during meiosis?

Nondisjunction during meiosis is the failure of homologous chromosomes or sister chromatids to separate properly during cell division. This event can lead to an unequal distribution of chromosomes in the resulting gametes. As a result, some gametes may end up with an extra chromosome, while others may have one fewer chromosome than normal.

This abnormality is significant because when such gametes participate in fertilization, they can lead to zygotes with either too many or too few chromosomes—these conditions are known as trisomy (having an extra chromosome) and monosomy (missing a chromosome). For instance, Down syndrome is a well-known example of trisomy, specifically trisomy 21, where there are three copies of chromosome 21.

The incorrect options highlight different scenarios that do not stem from nondisjunction. Some options suggest uniformity in gametes or health, which do not capture the varied and often problematic outcomes of nondisjunction. In essence, the consequence of nondisjunction is critical as it introduces genetic abnormalities in offspring, resulting from the presence of an improper number of chromosomes.