Advanced Placement (AP) Biology Practice Exam

What occurs during telophase in mitosis?

1. Chromosomes align at the cell equator

2. Spindle fibers shorten, pulling chromatids apart

3. Daughter cells begin to form, and cytokinesis typically starts

4. Nuclear envelope breaks down and chromosomes condense

The correct answer is: Daughter cells begin to form, and cytokinesis typically starts

During telophase in mitosis, daughter cells begin to form as the process of cell division progresses. This phase is characterized by the reformation of the nuclear envelope around each set of separated sister chromatids, which now reside at opposite poles of the cell. As the nuclear envelopes reform, the chromosomes begin to de-condense back into their more relaxed state, preparing for the next interphase. Cytokinesis, the physical division of the cytoplasm, typically begins during telophase. In animal cells, this is achieved through the formation of a cleavage furrow, while in plant cells, a cell plate forms to create a new cell wall between the two daughter cells. This process effectively results in two genetically identical daughter cells, completing the mitotic cycle. The other processes mentioned in the choices occur in different phases of mitosis. For example, chromosome alignment at the cell equator happens during metaphase, while the shortening of spindle fibers and separation of sister chromatids occurs in anaphase. The breakdown of the nuclear envelope and chromosome condensation are events associated with prophase. Thus, the correct option accurately describes the events taking place during telophase.