Protoplasmic respiration is respiration

Options

A. Occurring in protoplasm
B. Controlled by genetic factors
C. Occurring outside the mitochondira
D. Employing proteins as respiratory substrate.

Answer

### Step-by-Step Solution:

1. **Understanding Protoplasmic Respiration**:
- Protoplasmic respiration refers to the process where proteins are used as a substrate for respiration, particularly during extreme conditions such as starvation.

2. **Identifying the Context of Respiration**:
- Respiration is the breakdown of complex molecules into simpler ones, releasing energy that is used for various metabolic activities.

3. **Types of Substrates in Respiration**:
- Common substrates for respiration include carbohydrates (like glucose) and fats. These are typically used in what is known as "floating respiration."
- In rare cases, particularly during severe starvation when carbohydrate and fat reserves are depleted, proteins can serve as a substrate for respiration.

4. **Evaluating the Options Given**:
- **Option A**: "occurring in protoplasm" - This is misleading as protoplasmic respiration does occur in the protoplasm, but it is not the defining feature.
- **Option B**: "controlled by genetic factors" - This is incorrect as there is no direct genetic control over the use of proteins in respiration.
- **Option C**: "occurring outside mitochondria" - This is also incorrect; while some respiration processes may occur outside mitochondria, protoplasmic respiration is not defined by this.
- **Option D**: "employing protein as a respiratory substrate" - This is the correct statement, as protoplasmic respiration specifically involves the use of proteins during extreme conditions.

5. **Conclusion**:
- The correct answer to the question is **Option D: employing protein as a respiratory substrate**.