= Respiratory quotient
{title2=$\mathrm{RQ}=n_{\mathrm{CO}_2}/n_{\mathrm O_2}$}
{wiki}
The <respiratory quotient> compares <carbon dioxide> production with <molecular oxygen> consumption over the same interval. Complete <glucose> <oxidation> in the net equation above gives $\mathrm{RQ}=6/6=1$. In the ideal <respirometer gas balance> with no absorber, $f=0$, that conversion gives $D=0$: substantial <cellular respiration> can occur without any net gas contraction. A zero contraction therefore does not by itself demonstrate zero <metabolism>.
Other fuels, incomplete conversion and concurrent synthesis can alter the ratio. Absorber-based <respirometry> isolates <molecular oxygen> uptake by deliberately removing the other gas signal; it cannot independently determine the <respiratory quotient> or identify <glucose> as the consumed fuel. Separate <carbon dioxide> measurement would supply the missing account.
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