aerobic and anaerobic respiration 4.2.1

• breathing is moving air into and out of the lungs wheras respiration is a chemical reaction that takes place inside cells to release energy from food
• aerobic means with oxygen
• energy is released from glucose by a process known as respiration
• during aerobic respiration, chemical reactions take place inside the mitochondria in the cells of your body
• when glucose reacts with oxygen, energy is released
• carbon dioxide and water are formed as waste products
• the process is known as aerobic respiration because it uses oxygen from the air
• plants respire because they need energy for metabolic processed such as active transport and protein synthesis
• respiration involves many reactions, these are really important reactions, as respiration transfers the energy that the cells need to do just about everything - this energy is used for all living processes
• respiration is the process of transferring energy from glucose which goes on in every cell
• respiration is exothermic - it transfers energy to the environment
• aerobic respiration takes place in the cells of all living organisms all the time
• the substrates used in aerobic respiration include glucose and oxygen
• the energy released from aerobic respiration is used for:

  • muscle contractions to allow movement in animals
  • active transport
  • maintaining body temperature in mammals and birds
  • building large molecules from smaller ones such as proteins from amino acids
• the more active a cell is, the greater energy requirement, so the more mitochondria it needs eg a muscle cell would need more mitochondria than a fat cell
• aerobic respiration

  glucose + oxygen -> carbon dioxide + water (+energy)
• C6H12O6, O2, CO2 and H2O
• aerobic respiration releases more energy than anaerobic respiration as it is exothermic
• aerobic respiration is a slower process than anaerobic respiration because it is a longer process with more steps
• testing the products of aerobic respiration:

  carbon dioxide: when its bubbles through limewater, the water will turn cloudy

  water: will turn universal indicator green and will boil at exactly 100 degrees

  heat: use a thermometer
• anaerobic respiration is used in animals when there is not enough oxygen
• when you do vigorous exercise and your body cant supply enough oxygen to your muscles, they start doing anaerobic respiration as well as aerobic respiration
• anaerobic just means without oxygen, its the incomplete breakdown of glucose, making lactic acid
• anaerobic respiration uses only glucose
• anaerobic respiration takes place in the cytoplasm of the cell
• anaerobic respiration in animals:

  glucose -> lactic acid (+energy)
• anaerobic respiration does not transfer nearly as much energy as aerobic respiration, this is because glucose isnt fully oxidised
• anaerobic respiration is a shorter process than aerobic respiration because it is a shorter process with fewer stages
• when anaerobic respiration occurs over a prolonged period of time, lactic acid builds up and causes muscle fatigue
• oxygen debt is the amount of oxygen required to remove the lactic acid and replace the bodys reserves of oxygen
• testing for the products of anaerobic respiration in animals:

  lactic acid: feeling fatigue after lifting weights

  heat: thermometer
• plant and yeast cells can respire without oxygen too (in water logged soil if the plant roots cant get enough oxygen), but they produce ethanol and carbon dioxide instead of lactic acid
• anaerobic respiration in plant and yeast cells:

  glucose -> ethanol + carbon dioxide
• anaerobic respiration in yeast cells is called fermentation which can be used for making bread or brewing alcohol
• anaerobic respiration is not sustainable for a long period of time as ethanol levels which are poisonous and would eventually kill the plant/ yeast cell
• in bread making its the carbon dioxide from fermentation that makes bread rise
• in beer and wine making, its the fermentation process that produces alcohol
• mitochondria have a folded inner membrane to provide a large surface area for all the enzymes involved n aerobic respiration
• boys generally have to eat more than girls because they have a higher percentage of muscle cells, which require more energy than fat cells