Mandibles of cockroach are :

Options

A. short with grinding teeth
B. long and pointed
C. short without teeth
D. long and coiled

Answer

**Step-by-Step Solution:**

1. **Understanding the Structure of Mandibles:**
- Mandibles in cockroaches are paired structures located on either side of the mouth. They are essential for feeding and are adapted for grinding food.

2. **Characteristics of Cockroach Mandibles:**
- The mandibles are described as short and triangular in shape. They are hard and unjointed, which allows them to effectively break down food.

3. **Material Composition:**
- The mandibles are made of chitin, a tough and flexible material that provides strength and durability.

4. **Teeth Structure:**
- The inner margins of the mandibles have teeth-like structures. There are two types of teeth present:
- **Incising teeth**: These are used for cutting food.
- **Grinding teeth**: These are used for masticating or grinding the food.

5. **Functionality:**
- The presence of grinding teeth indicates that the mandibles are adapted for processing food, making them suitable for the diet of cockroaches.

6. **Evaluating the Options:**
- Option A: Short with grinding teeth - This is correct based on the characteristics discussed.
- Option B: Long and pointed - This is incorrect as cockroach mandibles are not long or pointed.
- Option C: Short without teeth - This is incorrect because mandibles do have teeth.
- Option D: Long and coiled - This is also incorrect as mandibles are not long or coiled.

7. **Conclusion:**
- The correct answer is Option A: Mandibles of cockroaches are short with grinding teeth.

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