The minimum number of chiasmata in a bivalent is/are

Options

A. One
B. Two
C. Three
D. Four

Answer

To solve the question regarding the minimum number of chiasmata in a bivalent, we can follow these steps:

### Step-by-Step Solution:

1. **Define Bivalent**:
- A bivalent is formed during meiosis and consists of two homologous chromosomes that have replicated and are paired together. Each homologous chromosome has two sister chromatids.

2. **Understanding Chiasmata**:
- Chiasmata are points where homologous chromosomes exchange genetic material during meiosis. This process is known as crossing over.

3. **Minimum Requirement**:
- For crossing over to occur, at least one chiasma is necessary. This means that in every bivalent, there must be at least one point of exchange between the homologous chromosomes.

4. **Conclusion**:
- Therefore, the minimum number of chiasmata in a bivalent is 1. While it is possible for there to be more than one chiasma (and sometimes up to three or more), the question specifically asks for the minimum.

5. **Final Answer**:
- The minimum number of chiasmata in a bivalent is **1**.