Which of the following statements is not ture?

Options

A. White muscle fibres are rich in mitrochondria
B. Muscles of eyeball movements are white fibres
C. Red muscle fibres are slower in contraction rate
D. White muscle fibres depend mainly on anaerobic glycolysis

Answer

To determine which statement about red and white muscle fibers is not true, let's analyze each statement based on the characteristics of these muscle fibers.

### Step-by-Step Solution:

1. **Understand the Characteristics of Muscle Fibers**:
- **Red Muscle Fibers**: These fibers are rich in mitochondria, contain high levels of myoglobin, have a denser capillary network, contract slowly, are less prone to fatigue, utilize oxygen efficiently, generate energy through aerobic respiration, and twitch slowly.
- **White Muscle Fibers**: These fibers have fewer mitochondria, lower myoglobin content, a less dense capillary network, contract quickly, fatigue easily, rely mainly on anaerobic glycolysis for energy, and twitch rapidly.

2. **Analyze Each Statement**:
- **Statement 1**: "White muscle fibers are rich in mitochondria."
- **Analysis**: This is false. White muscle fibers have fewer mitochondria compared to red muscle fibers.
- **Statement 2**: "Muscle of the eyeball movements are white muscle fibers."
- **Analysis**: This is true. Eye muscles are composed of white muscle fibers for quick movements.
- **Statement 3**: "Red muscle fibers are slower in contraction rate."
- **Analysis**: This is true. Red muscle fibers contract more slowly than white muscle fibers.
- **Statement 4**: "White muscle fibers depend mainly on anaerobic glycolysis."
- **Analysis**: This is true. White muscle fibers primarily rely on anaerobic metabolism for energy.

3. **Identify the False Statement**:
- From the analysis, the first statement is the only one that is not true: "White muscle fibers are rich in mitochondria."

### Conclusion:
The statement that is not true is: **"White muscle fibers are rich in mitochondria."**