There are two ways in which glucose is oxidized to provide energy in various organisms: (i) Anaerobic respiration: The respiration which takes place without oxygen is called anaerobic respiration.Example: Yeast and some bacteria break down glucose into ethanol and carbon dioxide. (ii) Aerobic respiration: The respiration which uses oxygen is called aerobic respiration.Example: Plants and animals break down glucose completely into carbon dioxide and water to release energy.