Which event describes what occurs at each new nucleus during telophase?

• A. Nuclear envelope disappears
• B. Nuclear envelope reforms around each chromosome set
• C. Nucleolus disappears
• D. Chromosomes duplicate

Answer: (B)

During telophase, two new nuclei form as the chromosome sets reach opposite poles and begin to de-condense. The nuclear envelope re-forms around each chromosome set, creating two distinct nuclei. Inside each new nucleus, the nucleolus reappears, signaling the resumption of ribosomal RNA synthesis. This reassembly of the nuclear envelope around each chromosome group is what defines the completion of the nuclear division portion of mitosis. In contrast, the nuclear envelope breaks down earlier in prophase, and chromosome duplication happens during the S phase of the cell cycle, not during telophase.