Which of the following is true with regard to red muscle fibres?

Options

A. 1. Short term contractions
B. 2. High intensity contractions
C. 3. More amount of sarcoplasmic reticulum
D. 4. More amount of oxygen storage

Answer

To determine which statement is true regarding red muscle fibers, we need to analyze the characteristics of red muscle fibers in comparison to white muscle fibers. Here’s a step-by-step breakdown:

### Step 1: Understand Muscle Fiber Types
- Muscle fibers are categorized into two main types: red (slow-twitch) and white (fast-twitch).
- Red muscle fibers are known for their endurance and ability to sustain longer contractions.

**Hint:** Remember that muscle fibers can be classified based on their contraction speed and endurance.

### Step 2: Characteristics of Red Muscle Fibers
- Red muscle fibers contain a higher amount of myoglobin, which gives them their red color and helps store oxygen.
- They are rich in mitochondria, which are essential for aerobic respiration, allowing these fibers to produce energy over extended periods without fatigue.

**Hint:** Focus on the role of myoglobin and mitochondria in energy production and oxygen storage.

### Step 3: Compare with White Muscle Fibers
- White muscle fibers, in contrast, have less myoglobin and mitochondria, leading to quicker but shorter bursts of energy.
- They rely more on anaerobic respiration, which leads to quicker fatigue and less oxygen storage.

**Hint:** Think about how the differences in myoglobin and mitochondria affect the function and endurance of muscle fibers.

### Step 4: Evaluate the Given Options
- **Short-term contractions:** This is characteristic of white muscle fibers, not red.
- **High-intensity contractions:** This is also a feature of white muscle fibers.
- **More amount of sarcoplasmic reticulum:** Red muscle fibers have less sarcoplasmic reticulum compared to white muscle fibers.
- **More amount of oxygen storage:** This is true for red muscle fibers due to their high myoglobin content.

**Hint:** Eliminate options that do not align with the characteristics of red muscle fibers.

### Step 5: Conclusion
The correct statement regarding red muscle fibers is that they have **more amount of oxygen storage** due to their high myoglobin content, which supports aerobic respiration.

**Final Answer:** More amount of oxygen storage (Option D) is true regarding red muscle fibers.

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