Respiration & Gas exchange

• Respiration is the process of transferring energy from glucose. It occurs in every cell in the body. Some energy is transferred by heat.
• The energy transferred by respiration cannot be used by cells, instead it creates ATP, which stores the energy needed for many different cell processes.
• Aerobic respiration occurs when there is plenty of oxygen available, and it is the most efficient way to transfer energy from glucose. It produces lots of ATP - 32 molecules per molecule of glucose.
• Aerobic respiration is the most common type of respiration.
• Aerobic word equation - Glucose + Oxygen ---> Carbon dioxide + water (+ energy)


  Chemical - C6H12O6 + 6O2 ---> 6CO2 + 6H2O
• Anaerobic respiration doesn't use any oxygen. It is not the best way to convert glucose to energy as it releases a lot less ATP compared to aerobic respiration. It produce 2 molecules of ATP per molecule of glucose.
• During anaerobic respiration glucose gets only partially broken down and lactic acid is produced. This lactic acid builds up in muscles and can lead to cramp.
• The word equation for anaerobic respiration in animals is -

  glucose ---> lactic acid (+ energy).
• The word equation for anaerobic respiration in plants is -

  glucose ---> ethanol + carbon dioxide (+ energy)
• When plants photosynthesise they use up CO2 from the atmosphere and they release O2 as a waste product.
• When plants respire they use up O2 and produce CO2 as a waste product.
• Waste products from plants that are gasses all leave through the stomata.
• Plants exchange gases through diffusion.
• The net change of gases depends on the light intensity.