Which one has the lowest respiratory quotient

Options

A. Glucose
B. Tripalmitin
C. Oxalic acid
D. Malic acid.

Answer

To determine which substance has the lowest respiratory quotient (RQ), we need to understand the RQ values associated with different types of substrates. The RQ is calculated as the ratio of carbon dioxide produced to oxygen consumed during respiration.

### Step-by-Step Solution:

1. **Understand the Definition of RQ**:
- 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.
- RQ = CO2 produced / O2 consumed.

2. **Identify the RQ Values for Different Substrates**:
- Carbohydrates (e.g., glucose) have an RQ of 1.
- Proteins have an RQ ranging from 0.8 to 0.9.
- Fats (e.g., tripalmitin) have an RQ of approximately 0.7.
- Organic acids (e.g., oxalic acid and malic acid) generally have an RQ greater than 1.

3. **Analyze the Given Options**:
- **Glucose**: RQ = 1 (carbohydrate).
- **Tripalmitin**: RQ = 0.7 (fat).
- **Oxalic Acid**: RQ > 1 (organic acid).
- **Malic Acid**: RQ > 1 (organic acid).

4. **Compare the RQ Values**:
- Among the options, glucose has an RQ of 1, tripalmitin has an RQ of 0.7, and both oxalic and malic acids have RQ values greater than 1.
- Therefore, tripalmitin has the lowest RQ value.

5. **Conclusion**:
- The substance with the lowest respiratory quotient among the given options is **tripalmitin**.

### Final Answer:
**Tripalmitin** has the lowest respiratory quotient.

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