Core Practical 16

• What does a respirometer measure?

  Rate of respiration
• How does a respirometer work?

  It measures oxygen volume decrease and pressure change
• What happens to the liquid in the respirometer as respiration occurs?

  The liquid moves down the pressure gradient
• What equipment is needed for a respirometer experiment?

  • Respirometer
  • Actively respiring organisms
  • Soda lime
  • Coloured liquid
  • Pipette
  • Solvent
  • Cotton wool
  • Stop clock
• What is the first step in the method for using a respirometer?

  Assemble the respirometer
• How much of one organism should be added to the boiling tube?

  5g
• What type of fluid is used in the respirometer?

  Coloured manometer fluid
• What should be done after placing the drop of coloured liquid?

  Use a syringe to draw the fluid
• What should be recorded after five minutes?

  The end position of the coloured liquid
• What is a hazard associated with broken glass?

  Cuts from sharp object
• What safety precaution should be taken with broken glass?

  Take care when handling glass objects
• What is the risk associated with soda lime?

  Corrosive
• What should be worn when handling soda lime?

  Eye protection
• What should be done if soda lime contacts the skin?

  Wash off skin immediately
• What is a biohazard risk in this experiment?

  Contamination
• What should be done after handling organisms?

  Wash hands with soap
• What is the analysis process for the respirometer experiment?

  1. Convert distance moved by liquid into volume using $\pi D$ formula.
  2. Multiply by distance moved.
  3. Convert volume into rate by dividing by five minutes.
  4. Convert rate into rate per gram by dividing by five grams.
• Why does soda lime absorb carbon dioxide?

  To measure only oxygen uptake changes
• What gas exchange process is ignored in this experiment?

  Photosynthesis
• Which organisms have a higher rate of respiration?

  Animals
• Why do animals have a higher respiration rate than plants?

  Higher metabolic rate and energy needs