Question

1. what is the defining event in metaphase? sister chromatids break apart and move to the opposite ends of the cell. dna condenses to chromosomes. the nuclear membrane breaks down. nuclear membrane forms around the two sets of chromatids at the far ends of the cell. chromosomes line up in the middle of the cell.

Explanation:

To determine the defining event of metaphase, we analyze each option:

• The first option describes anaphase (sister chromatids separating and moving to opposite ends).
• The second option describes prophase (DNA condensing into chromosomes and nuclear membrane breakdown).
• The third option describes telophase (nuclear membrane forming around chromatids at cell ends).
• The fourth option, "Chromosomes line up in the middle of the cell," is the defining event of metaphase, where chromosomes align at the cell's equatorial plate (metaphase plate).

Answer:

D. Chromosomes line up in the middle of the cell.