Fill in the following blanks with suitable words:
Anaerobic respiration in muscles occurs if there is no ………….. Available.

Answer

**Step-by-Step Solution:**

1. **Understanding the Types of Respiration**: There are two main types of respiration - aerobic and anaerobic. Aerobic respiration occurs in the presence of oxygen, while anaerobic respiration occurs when oxygen is not available.

2. **Context of the Question**: The question specifically asks about anaerobic respiration in muscles, which typically happens during intense physical activity when the body may not get enough oxygen.

3. **Identifying the Missing Word**: In the context of anaerobic respiration, the key factor that is missing is oxygen. When muscles are working hard, they may not receive sufficient oxygen, leading to anaerobic respiration.

4. **Filling in the Blank**: Based on the understanding that anaerobic respiration occurs in the absence of oxygen, we can fill in the blank: "Anaerobic respiration in muscles occurs if there is no **oxygen** available."

**Final Answer**: Oxygen

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