Advanced Placement (AP) Biology Practice Exam

What happens to a cell during cytokinesis?

1. The cell elongates and prepares for division

2. The cell's chromosomes duplicate

3. The cytoplasm divides into two separate daughter cells

4. The cell enters a resting phase

The correct answer is: The cytoplasm divides into two separate daughter cells

During cytokinesis, the primary event that occurs is the division of the cytoplasm, resulting in the formation of two separate daughter cells. This process follows mitosis, where the chromosomes are separated into two nuclei. The cell’s cytoplasm, which contains various organelles and components necessary for cell function, is physically divided and apportioned into the two new cells. This division is often facilitated by a structure known as the contractile ring, which is made up of actin and myosin filaments that constrict the cell membrane, ultimately leading to the cleavage furrow and separation. Each daughter cell then receives its share of the organelles and cytoplasm, allowing them to function independently. This is a crucial step in cell division, ensuring that genetic material and cellular components are properly allocated to maintain homeostasis and enable growth in the new cells. The other options do not accurately describe what occurs during cytokinesis. The elongation of the cell and preparation for division pertains to earlier stages in the cell cycle, while chromosome duplication happens during the S phase of interphase, not during cytokinesis. The resting phase refers to the G0 phase of the cell cycle, which is a state some cells enter when they are not actively dividing.