Mention two ways in which food …

Glucose is the vital energy source for all the organisms. The nutrition consumed is converted into carbohydrates in which glucose is the key ingredient. The glucose is oxidized to provide energy to the organism.  We know glucose is a huge molecule and breaks down into different smaller units. At first glucose which contains 6 carbon molecules is broken in the cytoplasm of cells of all organisms. In this process we obtain a 3 carbon molecule compound called pyruvate. Further break down of pyruvate takes place in different manners in different organisms. Following are the different ways in which the breakdown of glucose takes place
Anaerobic Respiration: The anaerobic respiration process takes place in the absence of oxygen. For example: In yeast during fermentation. In this process the pyruvate is converted into ethanol and carbon dioxide.
Aerobic Respiration: In aerobic respiration, breakdown of pyruvate takes place in the presence of oxygen to give rise to 3 molecules of carbon dioxide and water. The release of energy in aerobic respiration is much more than anaerobic respiration.
Lack of Oxygen: At times when there is a lack of oxygen in our body, mainly during vigorous activity, in our muscles, pyruvate is converted into lactic acid which is a 3 carbon molecule compound. The formation of lactic acid in muscles causes cramp.