What is the respiratory quotient of protein in the body?
**Core Concept**
The respiratory quotient (RQ) is a measure of the ratio of carbon dioxide produced (VCO2) to oxygen consumed (VO2) by the body during metabolism. It varies depending on the type of macronutrient being metabolized - carbohydrates, fats, or proteins.
**Why the Correct Answer is Right**
Proteins contain a mix of carbon, hydrogen, and nitrogen atoms. When broken down, they produce a certain amount of CO2 and require a corresponding amount of O2 for complete oxidation. The RQ of protein is approximately 0.8, indicating that for every molecule of O2 consumed, less than one molecule of CO2 is produced. This is because proteins have a higher nitrogen content compared to carbohydrates, resulting in less CO2 production per unit of O2 consumed.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is likely a distractor with an incorrect or incomplete value. Without a specific value, it's difficult to evaluate its accuracy.
* **Option B:** This option might be a plausible value for carbohydrates, which have an RQ of 1, but not for proteins.
* **Option C:** This option is likely incorrect, as the RQ of fats is typically around 0.7, not 1.1.
**Clinical Pearl / High-Yield Fact**
Remember that the RQ of a macronutrient can help you estimate the amount of CO2 produced relative to O2 consumed during metabolism. This can be useful in clinical settings where gas exchange is being monitored, such as in patients with respiratory or cardiac disease.
**Correct Answer: C. 0.8**