Number of longitudinal tracheal trunks in Cockroach is

Options

A. Three pairs
B. Three
C. Two
D. Two pairs

Answer

To determine the number of longitudinal tracheal trunks in a cockroach, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Spiracles**:
- Cockroaches have two types of spiracles: thoracic spiracles and abdominal spiracles.

2. **Understand the Function of Spiracles**:
- The thoracic spiracles lead into several horizontal trachea, while the abdominal spiracles lead into three tracheal tubes.

3. **Count the Tracheal Tubes**:
- From the abdominal spiracles, there are three tracheal tubes that open into longitudinal tracheal trunks.

4. **Identify the Longitudinal Tracheal Trunks**:
- Each of these tracheal tubes opens into three separate longitudinal tracheal trunks: dorsal, lateral, and ventral.

5. **Count the Pairs**:
- Since there are three types of trunks (dorsal, lateral, and ventral), and they exist in pairs on both sides of the cockroach, we have:
- 1 pair of dorsal trunks
- 1 pair of lateral trunks
- 1 pair of ventral trunks
- Therefore, the total number of longitudinal tracheal trunks is three pairs.

### Final Answer:
The number of longitudinal tracheal trunks in a cockroach is **three pairs**.

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