Saturday, 30 March 2013

2.37 describe experiments to investigate the evolution of carbon dioxide and heat from respiring seeds or other suitable living organisms

Collect the gas coming off the seed and bubble through lime water to see if it turns cloudy. Place in a cool environment and measure the surrounding air heating up.


  1. Replies
    1. set up two thermos flasks, one with germinating peas and one with boiled peas. insert a digital thermometer, surrounded by cotton wool, into both flasks and connect them to a data logger supplied with power. record the temperature of both flasks after one week. as the germinating peas can respire, the heat will be higher whilst the boiled ones can't therefore they remain at the same temperature

    2. Sorry I missed that bit out! Claudia thank you so much for writing this out :)

    3. Meh i will just right the one you posted Hannah.. my memory is bad for long terms :(

  2. Should we use CORMS for this?

    1. No CORMS is only for when you design your own experiment.


    this link describes it really well

    this is what we got told to learn for the exam from our teacher:

    Air gets through soda lime, which absorbs CO2 ( so Carbon Dioxide removed from circulation
    Air with no CO2 goes to plant— cannot photosynthesis but instead it respires, producing CO2.
    Hydrocarbon indicator will appear yellow( or limewater will go milky) due to increase in the concentrate of carbon dioxide
    Now it could photosynthesis ( has CO2)
    The rate of respiration is relative to the rate of heat release ( more respiration gives more heat) heat evolution should be measure using a digital thermometer to give accurate readings… Measure at the start, then every 2 days for a whole month. ( range of results= more reliable) Set up thermoflasks.

    If plant is covered with foil-> no photosynthesis-> no absorbing of CO2.. so hydrocarbon indicator remains yellow
    If add another organism-> more CO2-> hydrocarbon indicator wold be orange yellow.

  4. sorry for the super long comment-- Hannah, feel free to delete it if you find it too long :) -- or just add the info on the main post for others can see it .. ( TEAM WORK AHAHAHAHA)

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  6. This blog is so helpful, thank you so much Hannah!!

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  8. good explanation here -->

  9. wouldnt it be better to use hydrogencarbonate indicatorfor CO2? from what I understand the method is like this:
    For carbon dioxide production of plants, place identical types and amounts of plants in test tubes. Collect the gas coming off the seeds by placing a rubber bung in the opening. Coat one with silver foil to prevent light entering (so it respires instead of photosynthesising). Have a control empty test tube and at least one with a plant but without foil (you can also do do multiple ones in different light intensities). Leave for a few hours. Use hydrogen carbonate indicator solution to show the carbon dioxide concentration:
    High CO2 conc. = yellow
    Normal CO2 conc. = red
    Low CO2 conc. = purple

    also for heat I use the following:
    Place regular seeds into a vacuum container/thermos flask, and do the same (with the same type and amount of seeds into another) with seeds that have been boiled prior to the experiment. Insert a thermometer into each, surrounded by wet cotton. Record the temperature and leave for a few hours. then take the temperature of each again, and calculate the temperature change. The regular seeds should have gained heat, as they have been respiring, while the boiled seeds are no longer alive and will not have gained heat as they do not respire. Repeat for reliability.

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