Question

what does the respiratory exchange ratio (rer) measure exactly?
a) carbon dioxide uptake
b) oxygen uptake
c) carbon dioxide release
d) oxygen uptake and carbon dioxide release

Explanation:

The respiratory exchange ratio (RER) is calculated as the ratio of the volume of carbon dioxide released ($\text{VCO}_2$) to the volume of oxygen uptake ($\text{VO}_2$), i.e., $\text{RER} = \frac{\text{VCO}_2}{\text{VO}_2}$. So it measures both oxygen uptake and carbon dioxide release. Option a is incorrect as organisms release, not uptake, $\text{CO}_2$ in respiration. Option b and c only consider one aspect, while RER involves both.

Answer:

d) Oxygen uptake and carbon dioxide release