This is not true about white muscle

Options

A. More blood capillaries
B. Less blood capillaries
C. Less number of mitochondria
D. More sarcoplasmic reticulum.

Answer

To determine which statement is not true about white muscle fibers, we can analyze the characteristics of these fibers step by step.

### Step-by-Step Solution:

1. **Understanding White Muscle Fibers**:
- White muscle fibers, also known as fast-twitch fibers, are primarily used for short bursts of power and speed. They are less efficient for endurance activities.

2. **Myoglobin Content**:
- White muscle fibers contain a lower amount of myoglobin compared to red muscle fibers. Myoglobin is a protein that binds oxygen, which is why white muscle fibers appear lighter in color.

3. **Mitochondria Count**:
- These fibers have fewer mitochondria than red muscle fibers. Mitochondria are the powerhouses of the cell, responsible for aerobic respiration. Since white muscle fibers rely more on anaerobic metabolism, they do not require as many mitochondria.

4. **Sarcoplasmic Reticulum**:
- White muscle fibers have a higher amount of sarcoplasmic reticulum, which is important for the rapid release of calcium ions during muscle contraction. This allows for quick and powerful contractions.

5. **Blood Capillaries**:
- White muscle fibers have fewer blood capillaries compared to red muscle fibers. This is because they do not require as much oxygen for aerobic metabolism, as they primarily rely on anaerobic pathways for energy production.

6. **Conclusion**:
- The statement "more blood capillaries" is not true about white muscle fibers. Instead, they have fewer blood capillaries, fewer mitochondria, and more sarcoplasmic reticulum.

### Final Answer:
The statement that is not true about white muscle fibers is "more blood capillaries."

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