7.8—Core Practical 16 - respirometer, respiration rate and RQ

A respirometer can estimate oxygen consumption; respiratory quotient compares CO₂ produced with O₂ consumed. Both are rates or ratios that require the same time interval and controlled conditions.

Use a control, repeat measurements, absorb CO₂ only when the design requires oxygen uptake, and keep organism mass, temperature and activity comparable. Calculate RQ from gas volumes or moles.

A rise in oxygen uptake after warming may reflect faster respiration, but if temperature also changes gas pressure the apparent rate is confounded unless the control corrects it.

RQ from mixed substrates or anaerobic metabolism is not a clean substrate fingerprint. Separate instrument movement, oxygen consumption and the final quotient.