Respiration

• All organisms respire in order to release energy to fuel their living processes
• Aerobic respiration

  Uses glucose and oxygen
• Anaerobic respiration

  Uses only glucose
• Respiration releases energy - it is an exothermic reaction in which energy is given out to the surroundings
• Don't confuse respiration with photosynthesis. Photosynthesis is the process by which plants, and some bacteria, synthesise food molecules - which they then use, in addition to other things, for respiration
• Don't confuse respiration with breathing, which is ventilation (breathing in and out)
• Respiration happens in cells
• Why organisms need energy

  • To drive the chemical reactions needed to keep organisms alive
  • For movement
  • For cell division
  • To maintain constant conditions in cells and the body
  • For the transmission of nerve impulses
• Respiration is only around 40 per cent efficient
• As animals respire, heat is also released. In birds and mammals, this heat is distributed around the body by the blood. It keeps these animals warm and helps to keep a constant internal temperature
• Energy is also used for active transport - the transport of molecules against their concentration gradient from a region of low concentration to a region of high concentration
• Respiration

  Process by which organisms release energy to fuel their living processes
• Aerobic respiration

  • Uses glucose and oxygen
  • Releases energy
• Anaerobic respiration

  • Uses only glucose
  • Releases energy
• Aerobic respiration

  Glucose + oxygen → carbon dioxide + water + energy released
• Respiratory substrate

  Substance broken down by respiration to release energy
• Oxidise

  Chemical substances are oxidised by the addition of oxygen, removal of hydrogen or the removal of electrons
• Mitochondria

  Structures in the cytoplasm of all cells where aerobic respiration takes place
• Anaerobic respiration

  • Occurs without oxygen
  • Produces lactic acid in human muscle
  • Produces ethanol and carbon dioxide in yeast and some plants
• All organisms respire in order to release energy to fuel their living processes
• Aerobic respiration

  Uses glucose and oxygen
• Anaerobic respiration

  Uses only glucose
• Anaerobic respiration is economically important - many of our foods are produced by microorganisms respiring anaerobically
• Anaerobic respiration uses

  • Yeast to make alcoholic drinks
  • Yeast to produce bread
• Anaerobic respiration in yeast during beer or wine production

  1. Oxygen runs out

  2. Yeast switches to anaerobic respiration

  3. Ethanol and carbon dioxide are produced
• Anaerobic respiration in yeast used to produce bread

  1. Yeast respires using sugar added to the dough

  2. Bubbles of carbon dioxide make the bread rise

  3. Alcohol produced evaporates as the bread is baked
• Certain plants and plant cells also respire anaerobically, including plants that grow in marshes where oxygen concentrations will be low
• All organisms respire in order to release energy to fuel their living processes
• Aerobic respiration

  Uses glucose and oxygen
• Anaerobic respiration

  Uses only glucose
• Liver converts lactic acid back to glucose which needs oxygen
• All organisms respire in order to release energy to fuel their living processes
• Respiration

  Can be aerobic, which uses glucose and oxygen, or anaerobic which uses only glucose
• Oxygen debt

  The amount of oxygen required to remove the lactic acid, and replace the body's reserves of oxygen
• Response to exercise

  1. Breathing rate and volume of each breath increases to bring more oxygen into the body and remove the carbon dioxide produced

  2. Heart rate increases, to supply the muscles with extra oxygen and remove the carbon dioxide produced
• When a period of exercise is over

  Lactic acid must be removed
• If insufficient oxygen is available to the muscles

  Muscles begin to respire anaerobically
• Lactic acid is taken to the liver by the blood

  It is either oxidised to carbon dioxide and water, or converted to glucose, then glycogen
• Anaerobic respiration

  Lactic acid is produced from glucose, instead of carbon dioxide and water
• These processes require oxygen

  Breathing rate and heart rate do not return to normal straightaway