In mitosis, which phase features chromosomes aligned at the cell’s equator?

• A. Prophase
• B. Metaphase
• C. Anaphase
• D. Telophase

Answer: (B)

Chromosomes lining up at the cell’s equator happens during metaphase. At this stage the spindle apparatus is fully functional, and microtubules attach to kinetochores on each chromosome so that sister chromatids are pulled toward opposite ends. The chromosomes settle along the metaphase plate, a plane halfway between the two poles, ensuring they’re perfectly aligned for equal separation. In the earlier phase they condense and the nuclear envelope breaks down, but they don’t sit in the center yet. In the next phase, the centromeres split and the sister chromatids are pulled to opposite poles, and in the final stage the chromosomes arrive at the poles and the nuclear envelope reforms. So the defining moment where chromosomes are aligned at the center is metaphase.