What is cytokinesis?

• A. The division of the nucleus during cell division
• B. Division of the cytoplasm during cell division
• C. Reformation of the cell wall after division
• D. The replication of DNA

Answer: (B)

Cytokinesis is the division of the cytoplasm during cell division. After the nucleus has divided in mitosis, the cytoplasm splits to form two separate daughter cells. In animal cells, a contractile actin ring tightens the membrane, creating a cleavage furrow that pinches the cell membrane inward until two cells are produced. In plant cells, vesicles derived from the Golgi fuse at the center to form a cell plate that becomes separating membranes and, later, a separating cell wall. This step ensures each daughter cell gets cytoplasm and organelles. DNA replication occurs earlier in interphase, and the division of the nucleus (karyokinesis) happens during mitosis, so cytokinesis specifically describes the cytoplasmic split that completes cell division.