BIOLOGY - Physiology - Anaerobic Respiration

Sometimes animals and plants cannot get enough oxygen to respire aerobically, such as during intense exercise, but they still need to respire to survive. After all, everything relies on respiration for energy. Luckily there is a back-up plan; anaerobic respiration. The generalised equation for anaerobic respiration in muscles is: glucose --- lactic acid + energy. There is no oxygen involved in anaerobic respiration. It is much less efficient than aerobic respiration, and much less energy is released. This is because the glucose is only partially broken down. Another problem is that lactic acid is produced. This is actually a poisonous chemical that if it builds up in the body, the muscles stop working and you get muscle cramp.You can only get rid of the lactic acid by taking in oxygen again and thus replacing the oxygen debt. Oxygen is needed to break down the lactic acid, turning it into carbon dioxide and water. The oxygen supply can also run out for plants too, such as in waterlogged soils. This then forces plants to have to carry out anaerobic respiration, as they too need to respire constantly. The generalised anaerobic respiration equation for plants is: Glucose --- Ethanol + Carbon Dioxide + Energy. In yeast, this process is called fermentation and is used to bake bread and brew alcohol.