Regions of crossing over are indicated cytologically by

Options

A. Chromomeres
B. Chiasmata
C. Centromeres
D. Telomeres

Answer

To answer the question "Regions of crossing over are indicated cytologically by," we will analyze the options provided and determine the correct answer step by step.

### Step 1: Understand the options
The options given are:
1. Chromomeres
2. Chiasmata
3. Centromeres
4. Telomeres

### Step 2: Define each term
- **Chromomeres**: These are the bead-like structures found on chromosomes that represent regions of chromatin. They are not specifically involved in crossing over.
- **Chiasmata**: This is the point where two homologous non-sister chromatids exchange genetic material during meiosis. Chiasmata are the visible manifestations of crossing over.
- **Centromeres**: These are the regions of a chromosome where the two sister chromatids are joined together. They play a role in chromosome movement during cell division but are not involved in crossing over.
- **Telomeres**: These are the ends of chromosomes that protect them from deterioration. They do not play a role in crossing over.

### Step 3: Identify the correct answer
From the definitions, we can see that:
- **Chiasmata** is the only option that directly relates to the regions where crossing over occurs. It is the cytological indication of crossing over between homologous chromosomes.

### Conclusion
The correct answer to the question is **Chiasmata**.

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