Which one is not the character of red skeletal muscles ?

Options

A. Smaller diameter
B. More mitochondria
C. More sarcoplasmic reticulum
D. More blood capillaries

Answer

To determine which characteristic is not associated with red skeletal muscles, let's analyze the options given in the question step by step.

### Step-by-Step Solution:

1. **Understanding Red Skeletal Muscles**:
- Red skeletal muscles are also known as slow-twitch muscles. They are primarily responsible for endurance activities and are rich in myoglobin, which gives them their red color.

2. **Analyzing the Options**:
- **Option 1: Smaller Diameter**:
- Red skeletal muscles have a smaller diameter compared to white skeletal muscles. This is a characteristic of red muscles.
- **Option 2: More Mitochondria**:
- Red skeletal muscles contain a higher number of mitochondria. This is essential for aerobic respiration, which supports endurance activities. This is also a characteristic of red muscles.
- **Option 3: More Sarcoplasmic Reticulum**:
- Red skeletal muscles have less sarcoplasmic reticulum compared to white skeletal muscles. White muscles have more sarcoplasmic reticulum, which is involved in rapid contraction. Therefore, this is NOT a characteristic of red muscles.
- **Option 4: More Blood Capillaries**:
- Red skeletal muscles have a greater number of blood capillaries to supply oxygen for aerobic metabolism. This is a characteristic of red muscles.

3. **Conclusion**:
- The option that does not describe red skeletal muscles is **Option 3: More Sarcoplasmic Reticulum**. Red skeletal muscles have less sarcoplasmic reticulum compared to white skeletal muscles.

### Final Answer:
**More Sarcoplasmic Reticulum** is not a characteristic of red skeletal muscles.

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