To start respiration, a living cell requires

Options

A. only glucose
B. glucose + `O_2`
C. glucose, ATP and enzymes
D. glucose + enzymes

Answer

To start respiration, a living cell requires several key components. Let's break down the requirements step by step:

### Step-by-Step Solution:

1. **Understanding Respiration**:
- Respiration is a biochemical process that occurs in living cells to convert glucose into energy. This process can be aerobic (requiring oxygen) or anaerobic (not requiring oxygen).

2. **Identifying the Initial Requirement**:
- The first step of respiration is glycolysis, which is the breakdown of glucose. This step is crucial for both aerobic and anaerobic respiration.

3. **Components Needed for Glycolysis**:
- Glycolysis requires:
- **Glucose**: This is the primary substrate that is broken down.
- **ATP**: Adenosine triphosphate is required to initiate the process. Specifically, one molecule of ATP is used in the first step.
- **Enzymes**: A series of enzymes (specifically, 10 different enzymes) are necessary to facilitate the reactions that occur during glycolysis.

4. **Conclusion**:
- Therefore, to start respiration, a living cell requires glucose, ATP, and enzymes. This aligns with option number 3 from the provided choices.

### Final Answer:
The correct option is **glucose, ATP, and enzymes**.

---