Question

What is the difference between the amount of O2 inspired (taken up) and the CO2 expired per minute?

• A. 20 ml/min
• B. 50 ml/min
• C. 75 ml/min
• D. 100 ml/min

Hint:

Resting O2 uptake is about 250 ml/min and CO2 output is about 200 ml/min.

Answer 1

The Correct Option is B

Step 1: At rest, about 250 ml of oxygen is taken up by the body per minute, while about 200 ml of carbon dioxide is given off per minute.

Step 2: The difference between oxygen uptake and carbon dioxide output is therefore \(250 - 200 = 50\) ml/min.

Step 3: This difference reflects the respiratory exchange ratio (R), where \(R = \dfrac{\text{CO}_2 \text{ produced}}{\text{O}_2 \text{ consumed}} = \dfrac{200}{250} = 0.8\) at rest on a mixed diet.

Step 4: So the correct value of the difference is 50 ml/min, making option b correct.