Intimate pairing between the two members of each homologous chromosome pair is initiated by the process called as synapsis, leading to bivalent formation, occurs in

Options

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

Answer

To answer the question regarding the process of intimate pairing between homologous chromosomes leading to bivalent formation, we need to analyze the stages of meiosis, particularly during prophase I.

### Step-by-Step Solution:

1. **Understanding Homologous Chromosomes**: Homologous chromosomes are pairs of chromosomes that are similar in shape, size, and genetic content. Each member of the pair comes from one parent.

2. **Process of Synapsis**: The intimate pairing of these homologous chromosomes is initiated by a process known as synapsis. During synapsis, the homologous chromosomes align closely together.

3. **Formation of Bivalents**: As a result of synapsis, the paired homologous chromosomes form a structure called a bivalent (or tetrad). This structure consists of four chromatids (two from each homologous chromosome).

4. **Location in Meiosis**: The process of synapsis occurs during prophase I of meiosis, which is divided into several sub-stages.

5. **Identifying the Correct Stage**: The sub-stages of prophase I are:
- Leptotene
- Zygotene
- Pachytene
- Diplotene
- Diakinesis

6. **Identifying the Correct Answer**: The specific stage where synapsis occurs and bivalent formation begins is the Zygotene stage.

### Final Answer:
The intimate pairing between the two members of each homologous chromosome pair, initiated by the process called synapsis leading to bivalent formation, occurs in **Zygotene**.

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