During mitosis, the stage at which chromosomes lines up around the equator is?

Analyze the question: It asks which stage of mitosis has the chromosomes lining up at the equator (the middle) of the cell.

Explain the concept: Mitosis has four main stages, remembered as PMAT:

1. Prophase: Chromatin condenses into visible chromosomes. The nuclear membrane breaks down and the spindle begins to form.
2. Metaphase: Chromosomes line up along the equator (the metaphase plate) of the cell. Spindle fibres attach to the centromeres.
3. Anaphase: The sister chromatids separate and are pulled to opposite poles of the cell.
4. Telophase: Chromatids reach the poles, nuclear membranes re-form, and the cell divides (cytokinesis).

Solution:

• Option A, telophase: chromosomes are already at the poles, so this is wrong.
• Option B, metaphase (spelt "metasphase" in the question, which is a typo): chromosomes line up at the equator, so this is correct.
• Option C, anaphase: chromatids are moving apart toward the poles, so this is wrong.
• Option D, prophase: chromosomes are only condensing, and they are not yet aligned, so this is wrong.

Answer: B. Metaphase

Exam tip: Think "Metaphase = Middle". Both start with M. To remember the order, use PMAT: Please Make A Tea.