During muscle contraction, energy is provided by :-

Options

A. Acetyl-Co.A
B. Phosphagen
C. AMP
D. Glucose

Answer

**Step-by-Step Solution:**

1. **Understanding Muscle Contraction:**
- Muscle contraction requires energy to enable the muscle fibers to shorten and generate force. This energy is primarily derived from specific molecules within the muscle cells.

2. **Identifying Energy Sources:**
- The options provided for energy sources during muscle contraction are:
- Acetyl CoA
- Phosphagen
- AMP (Adenosine Monophosphate)
- Glucose

3. **Analyzing Each Option:**
- **Acetyl CoA:** This molecule is involved in the Krebs cycle and is important for aerobic respiration, but it is not the immediate source of energy during the initial phase of muscle contraction.
- **Phosphagen:** This refers to the ATP-PC (Adenosine Triphosphate - Phosphocreatine) system, which provides immediate energy for muscle contraction. ATP is stored in muscles and can be used quickly, while phosphocreatine helps regenerate ATP during short bursts of activity.
- **AMP:** While AMP can indicate low energy levels and stimulate pathways to generate more ATP, it is not a direct source of energy for muscle contraction.
- **Glucose:** This is a source of energy through glycolysis and aerobic respiration, but it takes longer to mobilize compared to the phosphagen system.

4. **Conclusion:**
- The primary source of energy during the initial seconds of muscle contraction is the phosphagen system, which relies on stored ATP and phosphocreatine. Therefore, the correct answer is **Phosphagen**.

**Final Answer:**
During muscle contraction, energy is provided by **Phosphagen**.

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