Final answer:
During metaphase II of meiosis II, chromosomes line up single file along the metaphase plate, preparing for the separation of sister chromatids that occurs in anaphase II.
Step-by-step explanation:
In metaphase II of meiosis II, the key event is that chromosomes line up single file down the middle of the cell. This is not to be confused with the separation of homologous chromosomes, which occurs during anaphase I of meiosis I, or the alignment of tetrads (pairs of homologous chromosomes), which takes place during metaphase I. At this stage of meiosis II, each chromosome is composed of two sister chromatids that are still connected at the centromere. The spindle fibers attach to the kinetochores of the sister chromatids, and the chromosomes align along the metaphase plate in preparation for their separation during anaphase II.