Which phase of mitosis is characterized by chromosomes aligning at the metaphase plate?

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

Answer: (B)

The phase where chromosomes line up in the middle of the cell is metaphase. In this stage, spindle fibers attached to kinetochores from opposite poles pull on the chromosomes so they arrange along the metaphase plate, an imaginary plane halfway between the two poles. This alignment, with sister chromatids attached to opposite sides, ensures that when they are pulled apart in the next phase, each new cell will receive the correct set of chromosomes. Before this, chromosomes condense during prophase; after this, sister chromatids are separated during anaphase and the cell completes division in telophase with the chromosomes de-condensing and the nuclear envelope forming again.