Final answer:
It is false that nondisjunction must occur during meiosis II to create a trisomy, as it can happen during either meiosis I or II, each producing gametes with abnormal chromosome numbers.
Step-by-step explanation:
The statement that nondisjunction must occur during meiosis II to create the possibility of generating a trisomy is false. Nondisjunction can occur during meiosis I or meiosis II, each with different outcomes. During meiosis I, if homologous chromosomes fail to separate, this leads to two gametes with an extra chromosome (n+1) and two gametes with one fewer chromosome (n-1). During meiosis II, if sister chromatids fail to separate, this results in one gamete with an extra chromosome, one gamete with one fewer chromosome, and two normal gametes with the correct chromosome number. Therefore, nondisjunction at either stage can lead to the formation of gametes with an abnormal number of chromosomes, which can contribute to a trisomy if one of these gametes is involved in fertilization.