When malic acid is respiratory substrate, the amount of `CO_(2)` released is

Options

A. `"More than" O_(2) "consumed"`
B. `"Less than" O_(2) "released"`
C. `"Equal to" O_(2) "consumed"`
D. `CO_(2) "is not released."`

Answer

To solve the question regarding the amount of carbon dioxide (CO₂) released when malic acid is used as a respiratory substrate, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Respiratory Quotient (RQ)**:
- The respiratory quotient (RQ) is defined as the ratio of the volume of carbon dioxide produced (CO₂) to the volume of oxygen consumed (O₂) during respiration.
- Mathematically, RQ = CO₂ produced / O₂ consumed.

2. **Identify the RQ Value for Malic Acid**:
- According to the information provided, when malic acid is used as a respiratory substrate, the RQ value is 1.33.

3. **Interpret the RQ Value**:
- An RQ value greater than 1 indicates that more carbon dioxide is produced than oxygen consumed.
- Specifically, an RQ of 1.33 means that for every unit of oxygen consumed, 1.33 units of carbon dioxide are produced.

4. **Conclusion**:
- Since the RQ for malic acid is 1.33, it follows that the amount of CO₂ released is more than the amount of O₂ consumed.

5. **Select the Correct Option**:
- Based on the interpretation of the RQ value, the correct answer to the question is that the amount of CO₂ released is **more than the oxygen consumed**.

### Final Answer:
The amount of CO₂ released when malic acid is a respiratory substrate is **more than the oxygen consumed**.