Which of the following structure will be seen in metaphase - I of meiosis - I, in a plant cell that has 64 chromosomes ?

Options

A. 16 bivalents
B. 16 dyad
C. 32 bivalents
D. 32 dyad

Answer

To solve the question regarding the structures seen in metaphase I of meiosis in a plant cell with 64 chromosomes, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Chromosome Number**:
- The question states that the plant cell has 64 chromosomes. This number represents the diploid (2n) chromosome count, meaning the organism has two sets of chromosomes.

2. **Determining Haploid Number**:
- To find the haploid (n) number, we divide the diploid number by 2.
- Calculation: n = 64 / 2 = 32.
- Therefore, the haploid number is 32.

3. **Meiosis Overview**:
- Meiosis consists of two rounds of cell division: Meiosis I and Meiosis II.
- In Meiosis I, homologous chromosomes are separated, and during metaphase I, homologous chromosomes align at the equatorial plate.

4. **Formation of Bivalents**:
- During prophase I of meiosis, homologous chromosomes pair up to form structures called bivalents or tetrads.
- Each bivalent consists of two homologous chromosomes, each made up of two sister chromatids.

5. **Counting Bivalents in Metaphase I**:
- Since there are 32 pairs of homologous chromosomes (as we calculated the haploid number to be 32), there will be 32 bivalents formed.
- Each bivalent consists of 4 chromatids (2 from each homologous chromosome).

6. **Conclusion**:
- In metaphase I of meiosis I, we will see 32 bivalents (tetrads) aligned at the equatorial plate of the cell.

### Final Answer:
The structure seen in metaphase I of meiosis I in a plant cell with 64 chromosomes will be **32 bivalents (tetrads)**.

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