Respiration

• What is the aim of the respiration investigation?

  Investigate the rate of respiration
• What equipment is needed for the respiration investigation?

  • Small animal (e.g., maggots, germinating pea)
  • Simple respirometer
  • Soda lime
  • Ruler
  • Marker
  • Electronic balance
  • Pipette
  • Dye
  • Forceps
  • Water bath

  
• What are the controlled variables in the respiration experiment?

  Mass of soda lime, temperature, time, air change
• What is the extension of the respiration investigation?

  • Repeat the setup over a range of temperatures
  • Use a water bath for control
  • Plot oxygen uptake against temperature
• What is a potential source of error when using animals in the experiment?

  Stress in captivity may affect respiration
• Why is it important to allow the animal to acclimatize?

  To ensure accurate respiration rate measurements
• How can air leakage affect the results of the experiment?

  It may lead to inaccurate respiration measurements
• What are the steps to set up the respirometer?

  1. Place soda lime in boiling tube.
  2. Weigh and add organisms.
  3. Add dye at capillary mouth.
  4. Open syringe connection and draw liquid.
  5. Equilibrate in water bath for 5 minutes.
  6. Mark starting fluid position.
  7. Close tap and start timing.
  8. Record fluid position at intervals.
  9. Calculate dye distance per minute.

  10. Repeat and calculate mean.
• How do you calculate the rate of respiration?

  Rate = volume of oxygen / mass of organism
• How long should the apparatus be left in the water bath?

  5 minutes
• What should be done at one-minute intervals during the experiment?

  Record the position of the fluid
• What is the purpose of using a dye in the respirometer?

  To visualize the movement of fluid
• Why is it important to handle animals carefully during the experiment?

  To avoid harming them and affecting results