Diakinesis is marked by

Options

A. Fromation of chiasmata
B. Terminalisation of chiasmata
C. Crossing over
D. Nuclear membrane persist

Answer

**Step-by-Step Solution:**

1. **Understanding Diakinesis**: Diakinesis is the final stage of prophase I in meiosis. It follows the stages of leptotene, zygotene, pachytene, and diplotene.

2. **Role of Chiasmata**: During the earlier stages of prophase I, particularly in the diplotene stage, crossing over occurs, leading to the formation of chiasmata. Chiasmata are the points where homologous chromosomes exchange genetic material.

3. **Termination of Crossing Over**: In diakinesis, the crossing over that began in the earlier stages is completed. This means that the chiasmata are still present but are about to be resolved.

4. **Separation of Homologous Chromosomes**: As diakinesis progresses, the homologous chromosomes, which are held together by the chiasmata, begin to separate. This separation is a key event that indicates the end of the crossing over process.

5. **Key Markers of Diakinesis**: The main markers of diakinesis include:
- The presence of fully formed chiasmata.
- The chromosomes becoming more condensed and visible under a microscope.
- The nuclear envelope breaking down, preparing for metaphase.

6. **Conclusion**: Therefore, diakinesis is marked by the termination of chiasmata formation and the completion of crossing over, leading to the separation of homologous chromosomes.

**Final Answer**: Diakinesis is marked by the termination of chiasmata and completion of crossing over.

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