Equipment
Safety
Method
- Respirometer
- 10x maggots
- Soda lime, to absorb CO2
- Coloured indicator fluid
- Stop clock
- Water baths
- Thermometer
- Spatula
- Boss, clamp and retort stand
- Dropping pipette
Safety
- Soda lime is corrosive therefore you need to be careful and handle it only using a spatula
Method
- Assemble the respirometer (see diagram below).Clamp the syringe and the respirometer in position when in use
- Place as known mass of one type of organism into the boiling tube (i.e. 10 maggots)
- Place a drop of coloured fluid at the open end of the glass tube using a 1cm3 pipette. Open the connection between the syringe and the respirometer. Use the syringe to draw the fluid onto the scale at the end furthest from the respirometer
- Mark the starting position of the fluid.
- Close the tap to isolate the respirometer from the atmosphere and the syringe and start the stop clock immediately
- Note the position of the fluid at one minute intervals for at least five minutes
- Repeat experiment with the test tube in a water bath at different temperatures, i.e 20,30,40 degrees
- Work out the distance travelled by the liquid during each minute. Record your results in a suitable table.
Results
Our class results show that the respiration rate of maggots was greatest at 40 degrees. The rate of respiration is directly proportional to the distance the fluid moved in the respirometer, therefore the greater the distance moved the higher the respiration rate was. In the graph we have discounted the results at 30 degrees as this was anomalous, this may have been due to a problem with the equipment.
The pathway for respiration involves a lot of enzyme action, therefore as enzymes are temperature sensitive so is respiration rate. As enzymes have an optimum temperature to function at which is in the region of 30-40 degrees, this has resulted in the rate also peaking at 40 degrees. As the temperature increased past 40 degrees the enzymes have become denatured, and therefore the substrates no longer bind to the active sites. The respiration rate now becomes 0 as no enzymes can function. At low temperatures the substrates have less energy therefore reaction rate is decreased and so the respiration rate is also low.
The pathway for respiration involves a lot of enzyme action, therefore as enzymes are temperature sensitive so is respiration rate. As enzymes have an optimum temperature to function at which is in the region of 30-40 degrees, this has resulted in the rate also peaking at 40 degrees. As the temperature increased past 40 degrees the enzymes have become denatured, and therefore the substrates no longer bind to the active sites. The respiration rate now becomes 0 as no enzymes can function. At low temperatures the substrates have less energy therefore reaction rate is decreased and so the respiration rate is also low.