Respiration rates

• What does the respiration rates experiment investigate?

  It helps calculate the oxygen consumption. This one specifically investigates the effect of temperature on woodlice.
• What could you use instead of woodlice?

  beans or germinating peas as a control.
• What are the steps to this experiment?

  1)Add granules of soda lime held in place with cotton wool.

  2)Gently shake organisms out of container and into boiling tube. Insert bung and capillary tube. Set up control.

  3)Place both tubes in racks of water at pre set temperature and tilt rack slightly. Wait for 5 mins for organisms to adjust.

  4)Hold beaker of coloured liquid to ends of capillary tube so liquid enters and mark position before then after 5 mins to measure distance travelled.

  5)Repeat experiment with water baths at different temperatures.
• What happens during 5 minute time of experiment?

  There will be a decrease in volume of air in test tube containing woodlice. This decrease reduces the pressure in tube causing coloured liquid to move towards test tube containing woodlice. The distance moved by the liquid in a given time is measured and this value helps calculate volume of oxygen taken in by woodlice.
• What is the max temperature that it can be for this experiment?

  40C as enzymes as organisms denature after this temperature.
• Why is cotton wool used in the experiment?

  It protects the person and the organism from soda lime which is corrosive.
• What is the ethical perspective of this experiment?

  Any live animal should be treated ethically so it's important not to leave woodlice in respirometer for too long or they may run out of oxygen and die.
• What are the variables of this experiment?

  Independent variable: temperature of water bath.

  Dependent variable: distance moved by liquid in tube.

  Control variable: glass beads/type of organism.
• Why is it important to have a control in this experiment?

  To ensure validity.