more respiration

• other respiratory substrates


  • other carbohydrates, proteins and lipids can be used
  • proteins and lipids enter at the Krebs cycle
  • lipids have the highest energy value, followed by proteins, then carbs
  • lipids have more hydrogens per unit mass, so it provides more H+ for oxidative phosphorylation, where the majority of ATP is produced
• RQ - respiratory quotient

  $RQ\ =$$\ \frac{volume\ of\ CO_2\ produced}{volume\ of\ O_2\ consumed}$
• Different respiratory substrates have different RQs

  • lipids - 0.7
  • proteins - 0.9
  • carbs - 1.0
  • lower RQs due to more oxygen required to oxidise fats and lipids
• RQ


  • higher RQs may be due to an organism being short on oxygen - anaerobic respiration is occurring
  • lower RQs due to photosynthesis
• respiratory substrates

  • average RQ for humans is between 0.7 and 1.0
  • proteins aren't usually used in respiration
• investigating rate of respiration in yeast using METHYLENE BLUE

  • a redox indicator dye, takes place of electron acceptors in oxidative phosphorylation (oxygen)
  • so can be used to determine rate of aerobic respiration
  • BLUE TO COLOURLESS
  • rate based on time for colour change to occur
• investigating rate of respiration in yeast using a GAS SYRINGE

  • prevent aerobic respiration - use liquid paraffin to prevent oxygen entering mixture
  • measure volume of carbon dioxide produced over time
• RESPIROMETER - measure the volume of oxygen produced over time

  • soda lime (potassium hydroxide) can be used to absorb carbon dioxide
  • germinating seeds, insects or yeast can be used as a respiring organism
  • control tube has glass beads the same volume as whatever is in the respiring tube
• RESPIROMETER - measure the volume of oxygen produced over time

  • respiring tube takes in oxygen
  • carbon dioxide is released, but absorbed by soda-lime (potassium hydroxide)
  • volume of gas decreases and so does pressure
  • gas syringe will lower, indicating a decrease in gas volume
  • liquid in U-tube of manometer move towards the respiring tube
  • rate can be calculated by recording distance the liquid in the tube moves, finding volume of oxygen taken in per minute