Which of the following features is not applicable for red muscle fibres ?

Options

A. It has high content of red colour oxygen storing pigment myoglobin . .
B. It also contains plenty of Mitochondria for maximum ATP production .
C. It has also high amount of sarcoplasmic reticulum .
D. It is also called as aerobic muscles.

Answer

To determine which feature is not applicable to red muscle fibers, we need to analyze the characteristics of red muscle fibers in comparison to white muscle fibers.

### Step-by-Step Solution:

1. **Understand Muscle Fiber Types**:
- There are two main types of skeletal muscle fibers: red muscle fibers (also known as slow-twitch fibers) and white muscle fibers (fast-twitch fibers).
- Red muscle fibers are rich in myoglobin and have a high number of mitochondria, which allows them to perform aerobic respiration.

2. **Characteristics of Red Muscle Fibers**:
- **High Myoglobin Content**: Red muscle fibers contain a significant amount of myoglobin, which is an oxygen-storing pigment. This is what gives them their reddish color.
- **Numerous Mitochondria**: They have a high number of mitochondria, which are essential for aerobic respiration and ATP production.
- **Aerobic Respiration**: Red muscle fibers primarily use aerobic metabolism to generate energy, which requires oxygen.

3. **Characteristics of White Muscle Fibers**:
- **Lower Myoglobin Content**: White muscle fibers have less myoglobin, which is why they appear pale.
- **Fewer Mitochondria**: They contain fewer mitochondria and primarily rely on anaerobic respiration for energy.
- **Higher Sarcoplasmic Reticulum**: White muscle fibers have a more extensive sarcoplasmic reticulum, which is important for rapid contraction and relaxation.

4. **Analyzing the Options**:
- **Option 1**: High content of myoglobin - This is true for red muscle fibers.
- **Option 2**: High number of mitochondria - This is also true for red muscle fibers.
- **Option 3**: High amount of sarcoplasmic reticulum - This is not true for red muscle fibers; instead, it is more characteristic of white muscle fibers.
- **Option 4**: Aerobic muscles - This is true for red muscle fibers.

5. **Conclusion**:
- The feature that is not applicable to red muscle fibers is the high amount of sarcoplasmic reticulum. Therefore, the correct answer is that red muscle fibers do not have a high amount of sarcoplasmic reticulum compared to white muscle fibers.

### Final Answer:
The feature that is not applicable for red muscle fibers is: **High amount of sarcoplasmic reticulum**.