During metaphase of mitosis, what key event occurs?

• A. The nuclear envelope breaks down.
• B. Chromosomes align at the cell's equatorial plane.
• C. Sister chromatids are pulled apart to opposite poles.
• D. The cell undergoes cytokinesis.

Answer: (B)

Verified step by step guidance

1. Understand the stages of mitosis: Mitosis is divided into several stages: prophase, metaphase, anaphase, and telophase. Each stage has distinct events that occur within the cell.
2. Identify the key event of metaphase: During metaphase, the chromosomes align at the cell's equatorial plane, also known as the metaphase plate. This alignment is crucial for the equal distribution of chromosomes to the daughter cells.
3. Differentiate between metaphase and other stages: In prophase, the nuclear envelope breaks down, and chromosomes condense. In anaphase, sister chromatids are pulled apart to opposite poles. Cytokinesis, the division of the cytoplasm, occurs after mitosis.
4. Recognize the role of the spindle apparatus: The spindle fibers attach to the centromeres of the chromosomes during metaphase, ensuring that each sister chromatid will be pulled to opposite poles during anaphase.
5. Summarize the importance of metaphase: The alignment of chromosomes at the equatorial plane ensures that each daughter cell will receive an identical set of chromosomes, maintaining genetic consistency across cell divisions.