When pairing occurs in chromosomes (meiosis) :-

Options

A. Leptotene
B. Zygotene
C. Pachytene
D. Diakinesis

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the stage in meiosis when pairing occurs in chromosomes. This refers to the process of homologous chromosomes coming together.

2. **Identifying the Stages of Meiosis**: Meiosis consists of several stages:
- Leptotene
- Zygotene
- Pachytene
- Diplotene
- Diakinesis

3. **Analyzing Each Stage**:
- **Leptotene**: This is the first stage of prophase I in meiosis where chromosomes begin to condense. However, pairing does not occur here; it is mainly about the condensation of chromatin into visible chromosomes.

- **Zygotene**: This is the second stage of prophase I where homologous chromosomes begin to pair up through a process called synapsis. This is the stage where chromosome pairing occurs, making it the correct answer.

- **Pachytene**: This is the third stage where crossing over occurs between non-sister chromatids of homologous chromosomes. While pairing has already occurred, this stage is more about genetic recombination rather than the initial pairing.

- **Diplotene**: In this stage, the homologous chromosomes begin to separate but remain attached at points called chiasmata. The pairing has already taken place by this stage.

- **Diakinesis**: This is the final stage of prophase I where chromosomes are fully condensed, and the chiasmata move to the ends of the chromosomes. The pairing is complete by this stage.

4. **Conclusion**: Based on the analysis, the correct answer is **Zygotene**, where the pairing of homologous chromosomes occurs.

**Final Answer**: The pairing occurs in chromosomes during the **Zygotene** stage of meiosis.

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