Select the correct statement regarding R.Q. ?

Options

A. RQ depends upon respiratory substrate
B. R.Q. is less than one in case or organic acids
C. R.Q. is always more than one in case of carbohydrate
D. R.Q. is 0.7 in succulent plants

Answer

### Step-by-Step Solution:

1. **Understanding R.Q. (Respiratory Quotient)**:
- The respiratory quotient (RQ) is defined as the ratio of the volume of carbon dioxide (CO2) produced to the volume of oxygen (O2) consumed during respiration.
- Mathematically, it can be expressed as:
\[ RQ = \frac{\text{CO2 produced}}{\text{O2 consumed}} \]

2. **Identifying RQ Values for Different Substrates**:
- The RQ value varies depending on the type of respiratory substrate being metabolized:
- For carbohydrates, RQ = 1 (equal amounts of CO2 produced and O2 consumed).
- For lipids, RQ = 0.7 (less CO2 produced compared to O2 consumed).
- For proteins, RQ = 0.9 (moderate CO2 production).
- For organic acids, RQ > 1 (more CO2 produced than O2 consumed).

3. **Evaluating the Statements**:
- The question asks to select the correct statement regarding RQ.
- The options provided are:
1. RQ for carbohydrates is 1.
2. RQ is less than 1 for organic acids.
3. RQ is always more than 1 in case of carbohydrates.
4. RQ is 0.7 in case of succulent plants.

4. **Analyzing Each Statement**:
- **Statement 1**: Correct. RQ for carbohydrates is indeed 1.
- **Statement 2**: Incorrect. RQ for organic acids is greater than 1.
- **Statement 3**: Incorrect. RQ for carbohydrates is exactly 1, not more than 1.
- **Statement 4**: Incorrect. RQ for succulent plants is 1, as starch is produced in photosynthesis.

5. **Conclusion**:
- The only correct statement regarding RQ is the first one: "RQ for carbohydrates is 1."