Question

what is the defining event in anaphase?

• dna condenses to chromosomes. the nuclear membrane breaks down.
• chromosomes line up in the middle of the cell.
• sister chromatids break apart and move to the opposite ends of the cell.
• nuclear membrane forms around the two sets of chromatids at the far ends of the cell.

Explanation:

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

• The first option describes events in prophase (DNA condensation, nuclear membrane breakdown).
• The second option describes metaphase (chromosomes align at the cell equator).
• The third option: In anaphase, sister chromatids separate (break apart) and are pulled to opposite poles (ends) of the cell. This is the key event of anaphase.
• The fourth option describes telophase (nuclear membrane re - formation around chromatids).

Answer:

C. Sister chromatids break apart and move to the opposite ends of the cell. (Here we assume the third option is labeled as C for clarity, following the common multiple - choice labeling convention. If the original options had different labels, adjust accordingly based on the actual option numbering.)