R.Q. for fatty substance/fat is

Options

A. Unity
B. Greater than one
C. Less than one
D. Zero

Answer

To determine the respiratory quotient (R.Q.) for fatty substances (fats), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of R.Q.**:
- The respiratory quotient (R.Q.) is defined as the ratio of the volume of carbon dioxide (CO2) produced to the volume of oxygen (O2) consumed during respiration.
- Mathematically, it is expressed as:
\[ R.Q. = \frac{\text{CO}_2 \text{ produced}}{\text{O}_2 \text{ consumed}} \]

2. **Identify R.Q. Values for Different Substrates**:
- Different substrates (carbohydrates, fats, and proteins) have different R.Q. values.
- For carbohydrates, the R.Q. is approximately 1 because the amount of CO2 produced is equal to the amount of O2 consumed.
- For proteins, the R.Q. is around 0.9.
- For fatty substances (fats), the R.Q. is less than 1.

3. **Explain Why Fats Have an R.Q. Less Than 1**:
- Fats are more energy-dense and require more oxygen for their oxidation compared to the amount of CO2 produced.
- This results in a lower R.Q. value, indicating that the ratio of CO2 produced to O2 consumed is less than 1.

4. **Conclusion**:
- Therefore, the R.Q. for fatty substances (fats) is less than 1.

### Final Answer:
The R.Q. for fatty substances (fats) is **less than 1**.

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