If each cell of the spore tetrad contains 4 chromosomes, how many pachytene tetrads are found in the meiocyte of that plant?

Options

A. 2
B. 8
C. 4
D. 16

Answer

To solve the question, we need to understand the relationship between the number of chromosomes in the spore tetrad and the number of pachytene tetrads in the meiocyte.

### Step-by-Step Solution:

1. **Understanding the Spore Tetrad**:
- The question states that each cell of the spore tetrad contains 4 chromosomes. A spore tetrad typically consists of four spores produced after meiosis.

2. **Identifying the Meiocyte**:
- A meiocyte is a cell that undergoes meiosis. During meiosis, the meiocyte goes through two rounds of division (meiosis I and meiosis II) to produce four daughter cells (spores).

3. **Pachytene Stage**:
- The pachytene stage is a specific phase during prophase I of meiosis where homologous chromosomes pair up and exchange genetic material. In this stage, each chromosome is replicated, and thus, the meiocyte will have double the number of chromosomes present in the spores.

4. **Calculating the Number of Chromosomes in the Meiocyte**:
- Since each spore has 4 chromosomes, the meiocyte, which is diploid (2n), will have 4 chromosomes in total before replication. After replication, during the pachytene stage, it will have 8 chromatids (4 pairs of homologous chromosomes).

5. **Determining the Number of Tetrads**:
- A tetrad is formed by the pairing of homologous chromosomes. Since the meiocyte has 4 chromosomes (2 pairs), it will form 2 tetrads during the pachytene stage.

6. **Final Answer**:
- Therefore, the number of pachytene tetrads found in the meiocyte of that plant is **2**.