The X-shaped structures formed during the largest stage of meiosis-I are called

Options

A. Bivalent
B. Chiasmata
C. Cross-overs
D. More than one option is correct

Answer

To solve the question regarding the X-shaped structures formed during the largest stage of meiosis-I, we can break down the process step by step:

### Step-by-Step Solution:

1. **Understanding Meiosis**:
- Meiosis is a type of cell division that reduces the chromosome number by half, resulting in four haploid cells. It consists of two main stages: meiosis I and meiosis II.

2. **Identifying the Stages of Meiosis I**:
- Meiosis I is divided into several stages: prophase I, metaphase I, anaphase I, and telophase I. Among these, prophase I is the longest and most complex stage.

3. **Focusing on Prophase I**:
- Prophase I can be further divided into five sub-stages: leptotene, zygotene, pachytene, diplotene, and diakinesis.

4. **Identifying Key Processes**:
- During the zygotene stage, homologous chromosomes begin to pair up.
- In the pachytene stage, crossing over occurs, where segments of DNA are exchanged between homologous chromosomes.

5. **Formation of Chiasmata**:
- The X-shaped structures that are formed as a result of crossing over are known as chiasmata. This occurs during the diplotene stage when the homologous chromosomes begin to separate but remain connected at the points where crossing over has occurred.

6. **Conclusion**:
- Therefore, the X-shaped structures formed during the largest stage of meiosis I (which is prophase I) are called **chiasmata**.

### Final Answer:
The X-shaped structures formed during the largest stage of meiosis-I are called **chiasmata**.

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