Which of the following is not a part of the respiratory system of Periplaneta americana ?

Options

A. Trachea
B. Sclerites
C. Spiracles
D. Both 'B' and 'C'

Answer

To solve the question "Which of the following is not a part of the respiratory system of Periplaneta americana?", we will analyze the options provided and determine which one does not belong to the respiratory system of the cockroach.

### Step-by-Step Solution:

1. **Identify the Organism**:
- The organism in question is Periplaneta americana, commonly known as the cockroach.

2. **Understand the Respiratory System**:
- The respiratory system of cockroaches consists of a network of **trachea** and **spiracles**.
- **Trachea**: These are tubes that transport air directly to the tissues.
- **Spiracles**: These are openings on the body surface that allow air to enter the tracheal system. Cockroaches have 10 pairs of spiracles.

3. **Analyze the Options**:
- **Option A: Trachea**: This is a part of the respiratory system.
- **Option B: Sclerates**: This refers to the hard exoskeleton of the cockroach, which is not involved in respiration.
- **Option C: Spiracles**: These are indeed part of the respiratory system.
- **Option D: Both B and C**: This option suggests that both Sclerates and Spiracles are not part of the respiratory system, which is incorrect since Spiracles are part of it.

4. **Conclusion**:
- The only option that is not a part of the respiratory system of Periplaneta americana is **Option B: Sclerates**.

### Final Answer:
The answer to the question is **Sclerates (Option B)**.

---