Respiration

Respiration is the release of energy from glucose [in living organisms].

Aerobic respiration is the release of energy by use of oxygen.

Anaerobic respiration is the release of energy without oxygen. It results in less energy being released. In plants, carbon dioxide and ethanol are produced whereas in animals, lactic acid is produced. The ethanol contains stored chemical energy that releases heat energy when burned.

When muscle cells respire anaerobically, they produce lactic acid. This poisons the muscle cells, often making them feel heavier. In order to get rid of the lactic acid, one has to respire aerobically and pay off the 'oxygen debt'. Oxygen oxidises lactic acid, therefore getting rid of it. 

When yeast respire anaerobically they release an enzyme called zymase. This catalyses the reaction of glucose into ethanol. This is used in fermentation. Yeast also release carbon dioxide which is beneficial in making bread rise.

The equation for aerobic respiration in plants and animals.

C6H12O6 + 6O2 = 6H2O + 6CO2

An experiment to investigate the release of carbon dioxide from seeds:

Bubble the gas emitted from the respiring seeds into limewater and see if it turns cloudy.

Place the seeds in cotton wool along with a thermometer and measure the increase in temperature.