Protein is respiratory substrate in

Options

A. Seeding state
B. Anaerobic respiration
C. Protoplasmic respiration
D. Floating respiration.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the condition under which proteins serve as a respiratory substrate.

2. **Identifying Common Respiratory Substrates**: Typically, carbohydrates and fats are the primary substrates used for respiration in cells.

3. **Considering Alternative Substrates**: In situations where carbohydrates and fats are not available, cells can utilize proteins as a respiratory substrate. This is an important point to note.

4. **Evaluating the Efficiency**: Using proteins as a substrate for respiration is considered inefficient. This is because the process produces ammonia as a by-product, which is toxic to cells.

5. **Defining Protoplasmic Respiration**: The type of respiration that occurs when proteins are used as a substrate, particularly in the absence of carbohydrates and fats, is known as protoplasmic respiration.

6. **Analyzing the Options**:
- **Feeding Stage**: This term is not related to respiratory substrates, so it is incorrect.
- **Anaerobic Respiration**: While this refers to respiration without oxygen, it does not specifically indicate the use of proteins as a substrate, making it incorrect.
- **Protoplasmic Respiration**: This is the correct answer, as it is the process where proteins are used as respiratory substrates.
- **Floating Respiration**: This involves the intake of nutrients like carbohydrates and fats from the environment, not proteins, so it is also incorrect.

7. **Conclusion**: Therefore, the correct answer is that proteins are respiratory substrates in protoplasmic respiration.

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