Pairing of homologous chromosomes occurs in -

Answer

To answer the question "Pairing of homologous chromosomes occurs in -", we need to understand the stages of meiosis, particularly prophase I.

### Step-by-Step Solution:

1. **Understanding Meiosis**: Meiosis is a type of cell division that reduces the chromosome number by half and is essential for sexual reproduction. It consists of two main stages: meiosis I and meiosis II.

2. **Focusing on Prophase I**: Prophase I of meiosis is crucial because it is during this phase that homologous chromosomes pair up. Prophase I is further divided into five sub-stages: leptotene, zygotene, pachytene, diplotene, and diakinesis.

3. **Identifying the Sub-stages**:
- **Leptotene**: Chromosomes begin to condense, and the nuclear membrane starts to break down.
- **Zygotene**: This is the key stage where homologous chromosomes begin to pair up. The process of pairing is known as synapsis.
- **Pachytene**: Recombination occurs here, where genetic material is exchanged between homologous chromosomes.
- **Diplotene**: The synaptonemal complex begins to break down.
- **Diakinesis**: The final preparations for separation occur, and the nuclear membrane re-forms.

4. **Conclusion**: The pairing of homologous chromosomes specifically occurs during the **zygotene** stage of prophase I in meiosis.

### Final Answer:
Pairing of homologous chromosomes occurs in **zygotene**.

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