B4.4.2.1

Aerobic and anaerobic respiration

Content

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 plant and yeast cells is represented by the equation:

glucose ethanol + carbondioxide

Anaerobic respiration in yeast cells is called fermentation and has economic importance in the manufacture of bread and alcoholic drinks.