7.7—Core Practical 15 - respiration in yeast

A respirometer measures oxygen uptake by a respiring organism. Soda lime or potassium hydroxide absorbs produced carbon dioxide, so the fall in gas volume reflects oxygen consumption.

Use a control with glass beads, keep temperature constant, measure capillary movement over time, reset between repeats and convert the movement using the capillary radius and distance.

If the manometer moves 2 cm in one minute and the capillary radius is r, the volume change is πr²h per minute; averaging repeats gives a more reliable rate.

Movement is not automatically oxygen volume unless CO₂ is absorbed and pressure/temperature are controlled. Living organisms require humane handling.