National League for Nursing (NLN) Science Practice Exam

In which phase of mitosis do the chromosomes align at the center of the cell?

1. Interphase

2. Metaphase

3. Prophase

4. Anaphase

The correct answer is: Metaphase

During mitosis, the phase where chromosomes align at the center of the cell is known as metaphase. In this phase, the chromosomes, which have already been replicated and condensed, are arranged along the metaphase plate (the equatorial plane of the cell). This alignment is a crucial step, as it ensures that each daughter cell will receive an identical set of chromosomes when the cell divides. The alignment at the center is facilitated by the spindle fibers, which attach to the centromeres of the chromosomes. This positioning is essential for the subsequent phase, anaphase, where the sister chromatids are pulled apart to opposite ends of the cell. Understanding this process is critical because it highlights the importance of chromosome segregation, which is fundamental to maintaining genetic stability in the daughter cells produced by mitosis.