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As living organisms respire they all produce heat. In this investigation we examine the production of heat energy by organisms as they respire. If they are placed in a vacuum flask (Thermos or Dewar), any heat the organisms produce will be retained and may be recorded and compared with a flask containing non-living material.
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Some seeds may be dressed with a fungicide to prevent rotting - take care when handling
It is important that any animal organism, whether mammal or
invertebrate, should not be deliberately exposed to stress during the course of these investigations.
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 | N.B. This experiment needs to be placed in a position where it can be left set up and undisturbed for at least 24 hours. As this is a long term experiment, you may wish to use the Remote logging facility of the datalogger.
- Assemble the apparatus as shown in the diagram. Connect the Temperature sensors and insert into the centre of each flask. Beans, peas, or wheat are suitable types of germinating seeds. Surface sterilise the seeds with a 12% bleach solution (sodium hypochlorite) for 15 minutes to kill fungal spores. The Control material can be either glass beads, dry seeds or seeds killed by boiling. Weigh out equal amounts of the seeds, the maggots and the control material and place in the flask.
For a maximum change in temperature the flasks can be 3/4 full (if so, reduce the time for logging to avoid stressing the maggots). Maggots require damp conditions so add a damp piece of cotton wool. Insert the temperature probes and fix with cotton wool bungs.
- Click the Launch button to load the logging software.
- Click on the Run Icon to begin a real-time logging or a remote logging.
- Leave the set-up and do not disturb any part of the apparatus.
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- Download the data if it has been collected remotely.
- Identify and label the set of data that corresponds to the temperature sensor in each flask.
- The results can be saved, printed or copied into your report document as required.
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- Why is it important to measure the temperature in the flask with no living organism present? Did the temperature change? If so, explain how.
- Compare the temperature in the flask containing maggots and germinating seeds. Which shows the greater temperature rise? Explain.
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 | Extension work can include:
Comparing yeast cultures in Thermos flasks respiring aerobically or anaerobically (layer of oil on top).
Examine the temperature at different levels in a compost heap - look at the effects of using wet or dry grass, compressed or uncompressed grass sterilised, ambient temperature, adding lime, silage accelerator etc.
Compare different types of seed e.g. oily and starchy seeds.
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