respiration and metabolism

• Define respiration?


  the process or transferring energy from glucose which goes on in every cell
• respiration is what type of reaction?

  exothermic
• state what respiration transfers energy for?

  • build up larger molecules from smaller ones
  • in animals it's used to contract muscles
  • in mammals and birds its used to keep their body temperature steady in colder surroundings
• what is metabolism?

  all the chemical reactions in a cell or body
• some reactions are larger molecules that are formed from smaller ones, give examples?

  • glucose molecules join together to form starch (in plants) glycogen (in animals) and cellulose (in plant cell walls)
  • lipid molecules made from one molecule of glycerol and three fatty acids
  • glucose is combined with nitrate ions and amino acids to make proteins
• some reactions are larger molecules being broken down into smaller ones, give examples?

  • glucose broken down in respiration to power all reactions to make molecules
  • excess protein is broken down to produce urea which is secreted in urine
• when and where does aerobic respiration take place in plants and animals?

  all the time in the mitochondria
• when does anaerobic respiration happen?

  when you do vigorous exercise and your body cannot supply enough oxygen

  • does not transfer as much energy as aerobic as the glucose does not fully oxidise
  • produces lactic acid
• what is anaerobic respiration in yeast cells and plants?

  glucose broken down to produce ethanol and carbon dioxide

  • called fermentation in yeast
  • bread making uses C02 from fermentation
• what else does your body do to reduce lactic acid?


  the blood that enters our muscles transports the lactic acid to the liver where it is converted back to glucose
• define oxygen dept?

  the amount of oxygen your body needs to react with the build up of lactic acid and remove it from the cells. form C02 and water are formed
• How do you investigate the effect of exercise on the body?

  1. measure breathing rate and heart rate
  2. take a pulse after doing each of these for 5 mins: sitting, gentle walking, slow jogging then running
  3. plot these results onto a bar chart
  4. to reduce random errors use a group and plot the average pulse rate
• give examples of metabolic reactions?

  • respiration
  • formation of proteins
  • formation / breakdown of glycogen
  • breakdown of excess protein or formation of urea
  • photosynthesis/ formation of glucose in plants