White muscle fibres

Options

A. Have abundant myoglobin and mitochondria
B. Have abundant myoglobin and a few mitochondria
C. Have a few molecules of myoglobin and abundant mitopchondria
D. Lack myoglobin and a few mitochondria

Answer

### Step-by-Step Solution for the Question on White Muscle Fibers:

1. **Understanding White Muscle Fibers**:
- White muscle fibers, also known as fast-twitch fibers, are characterized by their low myoglobin content and fewer mitochondria compared to red muscle fibers (slow-twitch fibers).

2. **Analyzing the Options**:
- **Option 1**: "Have abundant myoglobin and mitochondria."
- This option is incorrect because white muscle fibers have low myoglobin and mitochondria.
- **Option 2**: "Have abundant myoglobin and few mitochondria."
- This option is also incorrect for the same reason; white muscle fibers do not have abundant myoglobin.
- **Option 3**: "Have a few molecules of myoglobin and abundant mitochondria."
- This option is incorrect because while white muscle fibers do have few myoglobin, they do not have abundant mitochondria.
- **Option 4**: "Lack of myoglobin and few mitochondria."
- This option is correct as white muscle fibers indeed lack myoglobin and have fewer mitochondria.

3. **Conclusion**:
- Based on the analysis, the correct answer is **Option 4**: "Lack of myoglobin and few mitochondria."