A Level Biology Practice Exam

During which phase of mitosis do chromatin condense to form chromosomes?

1. Metaphase

2. Telophase

3. Prophase

4. Anaphase

The correct answer is: Prophase

During prophase, chromatin condenses into distinct chromosomes that become visible under a microscope. This is the phase where the genetic material that was loosely organized in the form of chromatin becomes tightly packed, allowing the individual chromosomes to be identified as two sister chromatids joined at the centromere. This condensation is essential for ensuring proper separation during the later phases of mitosis. In addition, the nuclear envelope begins to break down during prophase, further facilitating the processes that follow in mitosis. The other phases focus on different milestones of the cell division process, but it is in prophase that the initial changes to the chromatin structure take place.