A Level Biology Practice Exam

Cytokinesis plays a crucial role in the final stages of cell division, specifically in the process of separating the two newly formed daughter cells. After mitosis, where the nucleus and its contents are divided, cytokinesis ensures that the cytoplasm is also divided between these two cells. This division involves the formation of a cleavage furrow in animal cells or a cell plate in plant cells, which effectively partitions the cytoplasmic contents, including organelles and other materials, so that each daughter cell receives a sufficient share to function independently. The other options, while related to cell division, focus on different processes. Replicating DNA is part of the earlier S phase of the cell cycle, forming the genetic material that will be distributed. The formation of the mitotic spindle pertains to the metaphase of mitosis, where chromosomes align for separation. Ensuring accurate copying of genetic material is the role of various checkpoints and mechanisms that occur during replication and before cell division but is not specific to cytokinesis itself. Thus, the primary function of cytokinesis distinctly aligns with the division of the cytoplasm and organelles between the two daughter cells.