Humber Admissions Practice Test

Which phase of mitosis is characterized by the reformation of the nuclear envelope?

1. Prophase

2. Telophase

3. Anaphase

4. Metaphase

The correct answer is: Telophase

The phase of mitosis characterized by the reformation of the nuclear envelope is telophase. During this stage, the chromosomes, which have been separated and moved to opposite poles of the cell during anaphase, begin to de-condense back into chromatin. As the chromosomes relax, the nuclear envelope reforms around each set of separated sister chromatids, resulting in the formation of two distinct nuclei within the cell. This restoration of the nuclear membrane is a critical step in completing the mitotic process, preparing for the final division of the cytoplasm that will follow in cytokinesis. The other phases do involve significant biological activities, but they do not feature the reformation of the nuclear envelope. Prophase involves the condensation of chromatin into visible chromosomes and the breakdown of the nuclear envelope, while anaphase is marked by the separation and movement of sister chromatids towards opposite poles. Metaphase is characterized by chromosomes aligning along the metaphase plate, yet does not involve any nuclear envelope dynamics. Therefore, telophase stands out as the phase where the nuclear envelope is reconstructed, signifying the nearing completion of mitosis.