What occurs due to non-disjunction during cell division?

Non-disjunction during cell division refers to the failure of homologous chromosomes or sister chromatids to separate properly during meiosis or mitosis. This results in gametes or daughter cells that have an abnormal number of chromosomes. When non-disjunction occurs in meiosis, it can lead to the formation of gametes with either one extra chromosome or one less chromosome than the normal haploid number.

When these gametes are involved in fertilization, they can result in conditions such as trisomy (where an individual has three copies of a particular chromosome) or monosomy (where an individual has only one copy of a particular chromosome). These chromosomal abnormalities can lead to various genetic disorders, such as Down syndrome (trisomy 21) or Turner syndrome (monosomy X).

In contrast, the other choices do not accurately represent the outcomes associated with non-disjunction. Normal gamete formation involves the correct separation of chromosomes, gene duplication pertains to the replication of a segment of DNA rather than chromosomal separation issues, and increased genetic diversity is typically achieved through mechanisms like sexual reproduction and crossing over, not through errors like non-disjunction.