What happens during metaphase II of meiosis? Homologous chromosomes form, and crossing over occurs between them. The nuclear membrane begins to form around haploid sets of chromosomes. Homologous chromosomes separate, but sister chromatids remain joined at their centromeres. Sister chromatids are distributed in a single layer across the center of the cell. Homologous chromosomes are randomly arranged in the middle of the cell. Sister chromatids separate from each other and migrate to opposite ends of the cell.
The Correct Answer and Explanation is:
The correct answer is:
“Sister chromatids are distributed in a single layer across the center of the cell.”
Explanation:
Meiosis is a specialized form of cell division that reduces the chromosome number by half, producing four haploid cells from a single diploid cell. It consists of two consecutive divisions: Meiosis I and Meiosis II.
Metaphase II is part of Meiosis II, which resembles mitosis but occurs in haploid cells. During Metaphase II, the chromosomes (which consist of two sister chromatids) align along the metaphase plate in a single file line, not in homologous pairs as seen in Metaphase I.
Key Events of Metaphase II:
Chromosome Alignment: Each chromosome, made up of two sister chromatids, is positioned along the metaphase plate (center of the cell). This alignment ensures that each new cell receives an equal set of chromatids during the next phase.
Spindle Fiber Attachment: Spindle fibers from opposite poles attach to the kinetochores of each sister chromatid. This connection is crucial for their proper separation in the next phase, Anaphase II.
No Homologous Chromosomes: Unlike Metaphase I, where homologous chromosomes pair up, Metaphase II involves individual chromosomes lining up in a single row.
Why Other Choices Are Incorrect:
Homologous chromosomes form, and crossing over occurs between them → This occurs in Prophase I, not Metaphase II.
The nuclear membrane begins to form around haploid sets of chromosomes → This happens in Telophase II, not Metaphase II.
Homologous chromosomes separate, but sister chromatids remain joined at their centromeres → This occurs in Anaphase I, not Metaphase II.
Homologous chromosomes are randomly arranged in the middle of the cell → Homologous chromosomes do not appear in Meiosis II; only sister chromatids are present.
Sister chromatids separate from each other and migrate to opposite ends of the cell → This happens in Anaphase II, not Metaphase II.
Thus, Metaphase II is characterized by the single-layer alignment of sister chromatids along the center of the cell, preparing for their separation in Anaphase II.
