Which process results in two nuclei with the same chromosome number as the original cell?

• A. Mitosis
• B. Meiosis
• C. Cytokinesis
• D. Binary Fission

Answer: (A)

Two nuclei with the same chromosome number as the original cell come from mitosis. In mitosis the cell’s duplicated chromosomes are evenly separated into two new nuclei, so each nucleus ends up with the same number of chromosomes as the starting cell. After this nuclear division, cytokinesis splits the cytoplasm to form two separate cells, but the key step that preserves chromosome number and creates two nuclei is mitosis. Meiosis, on the other hand, halves the chromosome number and yields four nuclei. Cytokinesis alone doesn’t produce nuclei, it just divides the cell after the nucleus has divided. Binary fission occurs in prokaryotes and doesn’t involve a true nucleus.