Number of ATP formed per molecule of oxygen used in respiration is

Options

A. 16
B. 8
C. 6
D. 4

Answer

To solve the question regarding the number of ATP formed per molecule of oxygen used in respiration, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding Respiration**:
- Respiration is the process by which glucose (C6H12O6) is broken down to produce energy in the form of ATP.

2. **Phases of Respiration**:
- Respiration can be divided into two main phases:
- **Glycolysis**: This is the anaerobic phase that occurs in the cytoplasm.
- **Krebs Cycle**: This is the aerobic phase that occurs in the mitochondria.

3. **ATP Production in Glycolysis**:
- During glycolysis, one molecule of glucose is converted into two molecules of pyruvate.
- The net production of ATP during glycolysis is **2 ATP**.

4. **ATP Production in Krebs Cycle**:
- In the Krebs cycle, which follows glycolysis, a total of **34 ATP** molecules are produced from the breakdown of the products of glycolysis.

5. **Total ATP Production**:
- Adding the ATP produced in both phases, we have:
- Glycolysis: 2 ATP
- Krebs Cycle: 34 ATP
- **Total ATP = 2 + 34 = 36 ATP** from one molecule of glucose.

6. **Oxygen Utilization**:
- In aerobic respiration, 6 molecules of oxygen are used to completely oxidize one molecule of glucose.
- Therefore, if 36 ATP are produced from 6 molecules of oxygen, we can calculate the ATP produced per molecule of oxygen.

7. **Calculating ATP per Oxygen**:
- To find the number of ATP produced per molecule of oxygen, we divide the total ATP by the number of oxygen molecules:
- **ATP per molecule of oxygen = Total ATP / Number of oxygen molecules**
- **ATP per molecule of oxygen = 36 ATP / 6 O2 = 6 ATP**.

8. **Final Answer**:
- Thus, the number of ATP formed per molecule of oxygen used in respiration is **6**.

### Conclusion:
The correct answer to the question is **6 ATP** per molecule of oxygen used in respiration.

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