Cellular respiration is an exothermic reaction which is continuously occurring in living cells. The energy transferred supplies all the energy needed for living processes.
Respiration in cells can take place aerobically (using oxygen) or anaerobically (without oxygen), to transfer energy.
Organisms need energy for:
Chemical reactions to build larger molecules
Movement
Keeping warm
Aerobic respiration is represented by the equation:
Glucose + Oxygen --> Carbon dioxide + Water
Anaerobic respiration in muscles is represented by the equation:
glucose --> lactic acid
As the oxidation of glucose is incomplete in anaerobic respiration much less energy is transferred than in aerobic respiration.
Anaerobic respiration in plant and yeast cells is represented by the equation:
glucose --> ethanol + carbon dioxide
Anaerobic respiration in yeast cells is called fermentation and has economic importance in the manufacture of bread and alcoholic drinks.
