Exoskeleton of each segment in cockroach consists of

Options

A. Dorsal tergum and a ventral sternum
B. Dorsal sternum and a ventral tergum
C. Sternum only
D. Tergum only

Explanation

### Step-by-Step Solution:

1. **Understanding the Exoskeleton**: The exoskeleton of a cockroach is a protective outer covering that provides structure and support. It is primarily made of a substance called chitin.

2. **Composition of Exoskeleton**: Chitin is a structural polysaccharide that forms the main component of the exoskeleton. It is known for its strength and durability.

3. **Arrangement of Chitin**: In the cockroach, the chitin is not just a single layer but is arranged in plates. These plates provide flexibility and protection to the cockroach.

4. **Identification of Plates**: The plates of the exoskeleton are categorized based on their position:
- **Dorsal Plates**: The plates that are located on the upper side (back) of the cockroach are referred to as the tergum.
- **Ventral Plates**: The plates located on the lower side (belly) are called the sternum.

5. **Articulation of Plates**: The plates are connected by flexible membranes known as the arthrodial membranes. These membranes allow for movement between the plates, giving the cockroach the ability to move freely.

6. **Conclusion**: Therefore, the exoskeleton of each segment in a cockroach consists of a dorsal tergum and a ventral sternum, along with the arthrodial membranes that connect them.

### Final Answer:
The exoskeleton of each segment in a cockroach consists of a dorsal tergum and a ventral sternum.

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