A Level Biology Practice Exam

During telophase, what significant cellular change occurs?

1. Spindle fibers disintegrate

2. Nuclear envelope reforms

3. Chromosomes condense

4. Chromatin is synthesized

The correct answer is: Nuclear envelope reforms

During telophase, a significant change that takes place is the reformation of the nuclear envelope. As the separated sister chromatids reach the opposite poles of the cell, the spindle fibers that facilitated their movement begin to disassemble. This marks the final stage of mitosis where the chromosomes, which were previously condensed and visible, start to decondense back into chromatin. The reforming nuclear envelope surrounds each set of chromosomes, creating two distinct nuclei within the now dividing cell. This process is crucial for ensuring that each daughter cell will have its own nucleus containing the correct amount of genetic material, maintaining genetic continuity and stability. While spindle fiber disintegration does occur, it is not as significant as the reformation of the nuclear envelope, since the envelope's return marks the restoration of the cell’s nuclear structure. The chromosomes condensing is characteristic of earlier phases of mitosis, specifically prophase and metaphase, rather than telophase. Likewise, chromatin synthesis is not a direct event of telophase; rather, it's part of the cell's preparation for the next interphase. Thus, the restoration of the nuclear envelope stands out as a key and defining feature of telophase.