AQA GCSE Biology- Respiration

Designed for the new specification AQA GCSE course but can be modified for other exam boards.

29 slides cover: respiration.

By the end of the powerpoint students would have covered /:

4.4.2.1 Aerobic and anaerobic respiration
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 + carbon dioxide

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

**4.4.2.2 Response to exercise **
During exercise the human body reacts to the increased demand for energy.

The heart rate, breathing rate and breath volume increase during exercise to supply the muscles with more oxygenated blood.

If insufficient oxygen is supplied anaerobic respiration takes place in muscles. The incomplete oxidation of glucose causes a build up of lactic acid and creates an oxygen debt. During long periods of vigorous activity muscles become fatigued and stop contracting efficiently.

(HT only) Blood flowing through the muscles transports the lactic acid to the liver where it is converted back into glucose. Oxygen debt is the amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells.