Students should be able to describe cellular respiration as 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. • Students should be able to compare the processes of aerobic and anaerobic respiration with regard to the need for oxygen, the differing products and the relative amounts of energy transferred. • 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. Students should recognise the chemical symbols: C6H12O6, O2, CO2 and H2O. • 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 yeast cells is called fermentation and has economic importance in the manufacture of bread and alcoholic drinks.