Question

During ___, a spindle appears while the nuclear envelope fragments and the nucleolus disappears. Only one set of sister chromosomes from each pair of homologous chromosomes is present.

• A. Prophase I
• B. Prophase II
• C. Telophase I
• D. Metaphase II

Answer 1

The correct option is B Prophase II

Prophase II is the first stage in meiosis II, during which the disintegration of the nucleolus and nuclear envelope is observed. During this stage, the shortening and thickening of the chromatids, and the replication and movement of centrosomes to polar regions are also seen.
At the end of Meiosis I, two haploid daughter cells are formed. Therefore, there is only one set of sister chromosomes from each pair of homologous chromosomes during prophase II of meiosis II.
A major difference between prophase I and prophase II is that crossing over between chromosomes takes place only in prophase I and not during prophase II.
During telophase I, the homologous chromosome pairs completes their migration to the two poles as a result of the action of the spindle and a nuclear envelope reforms around each chromosome set.
During metaphase II, which is the second stage of meiosis II, the chromosomes become arranged on the metaphase plate and are attached to the now fully formed spindle.