respiration; germination; fermentation; anaerobic & aerobic
When living things respire they use up oxygen. This can be monitored using an oxygen sensor. The living thing can be a plant, animal or microorganism. Maggots, locusts, or yeast are often used and so can pond-weed. If you use Elodea, its container should be kept in the dark or wrapped in foil.
It is also quite easy to show how temperature affects the rate of respiration
– however, in this example, the oxygen sensor should be able to compensate for its own response to temperature changes.