Final answer:
Eggs have more problems dividing and nondisjunction is more likely as women age, especially after age 35, leading to a higher risk of chromosomal abnormalities like Down syndrome due to gametes with an abnormal number of chromosomes.
Step-by-step explanation:
Nondisjunction is more likely to occur as women age, particularly when the woman is over 35. This is because egg cells, or oocytes, age as well, which can lead to an increase in cell division errors during meiosis I and meiosis II. Nondisjunction occurs when there is a failure in the proper separation of homologous chromosomes during meiosis I, or sister chromatids during meiosis II, resulting in gametes, such as eggs, with an abnormal number of chromosomes (n+1 or n-1). This can cause fertility problems and increase the risk of chromosomal disorders like Down syndrome, which is characterized by an extra copy of chromosome 21.