4.2.1: Aerobic and anaerobic respiration
Not started yet — this one needs some love.
Cellular respiration is an exothermic reaction which is continuously occurring in living cells.
The energy transferred by respiration supplies the energy needed for living processes.
Organisms need energy for chemical reactions to build larger molecules, movement and keeping warm.
Aerobic respiration uses oxygen: glucose + oxygen → carbon dioxide + water.
Aerobic respiration transfers more energy than anaerobic respiration because glucose is fully oxidised.
Anaerobic respiration happens without oxygen and transfers less energy because glucose is incompletely oxidised.
Anaerobic respiration in muscles: glucose → lactic acid.
Anaerobic respiration in plant and yeast cells: glucose → ethanol + carbon dioxide.
Fermentation is anaerobic respiration in yeast cells and is used to make bread and alcoholic drinks.
Common exam mistakes
Do not say respiration produces energy; energy is transferred by respiration.
Do not say aerobic respiration happens without oxygen or anaerobic respiration uses oxygen.
Do not give lactic acid as the product of anaerobic respiration in yeast or plant cells.
Do not give ethanol and carbon dioxide as the products of anaerobic respiration in muscles.
Do not say anaerobic respiration transfers more energy than aerobic respiration; incomplete oxidation transfers less energy.