Final answer:
Nondisjunction can occur during either meiosis I or II, with different results. It can lead to the formation of gametes lacking a certain chromosome or with two copies of a certain chromosome. One outcome that is not possible is when sister chromatids fail to separate during meiosis II.
Step-by-step explanation:
Nondisjunction can occur during either meiosis I or II, with differing results. If homologous chromosomes fail to separate during meiosis I, the result is two gametes that lack that particular chromosome and two gametes with two chromosome copies. If sister chromatids fail to separate during meiosis II, the result is one gamete that lacks that chromosome, two normal gametes with one chromosome copy, and one gamete with two chromosome copies.
Therefore, the statement that is not a possible outcome as a result of meiotic nondisjunction is:
- Nondisjunction only occurs when sister chromatids do not separate in meiosis II, resulting in the formation of gametes containing n+1 and n-1 chromosomes.