Which of the following events characterizes metaphase of mitosis?
I. Movement of chromosomes to the equatorial plane (metaphase plate) of the cell.
II. A spindle fiber attaches to each sister chromatid.
III. Separation of sister chromatids that are being pulled to the poles of the cell.

• A. I.
• B. II.
• C. III.
• D. I and II.
• E. All of these

Answer: (A)

Verified step by step guidance

1. Understand the stages of mitosis: Mitosis is divided into several stages, including prophase, metaphase, anaphase, and telophase. Each stage has distinct events that occur.
2. Identify the key event of metaphase: During metaphase, chromosomes align at the equatorial plane of the cell, known as the metaphase plate. This alignment is crucial for the next stage of mitosis.
3. Recognize the role of spindle fibers: In metaphase, spindle fibers attach to the centromeres of the sister chromatids. This attachment is necessary for the subsequent separation of chromatids.
4. Differentiate between metaphase and anaphase: While metaphase involves the alignment of chromosomes and attachment of spindle fibers, anaphase is characterized by the separation of sister chromatids as they are pulled toward opposite poles.
5. Evaluate the given options: Based on the understanding of metaphase, determine which events (I, II, III) accurately describe this stage. Metaphase is characterized by events I and II, but not III, as separation occurs in anaphase.