Photosynthesis and Carbon Dioxide

Discussion in 'Supporting Biology' started by archive, Apr 6, 2015.

  1. archive

    archive Administrator Site Admin

    User: Cricketfool

    We have tried this practical twice recently without success. We cut small discs of Ivy (Hedera) leaf and put them into 5ml syringes containing various concentrations of Soium Hydrogen Carbonate with a lamp shone at them. We see which discs rise to the surface first as they produce oxygen. We had no succes despite having got good results last year and in June. We also tried using Potassium Hydrogen Carbonate but again had no success. Is it the weather, temperature...? Any ideas anyone?
  2. archive

    archive Administrator Site Admin

    User: Jyeardly

    No it's biology

    We have had similar problems using geranium (even doing basic starch tests)
    the best idea we had was the wave lengths being produced by the lamp I tried a "daylight" craft lamp but the results were very mixed
    even doing it in test tubes as it was suggested that the syringe was "blocking light"
  3. archive

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    User: Marilyn

    Hello everyone. May I suggest the use of passing carbon dioxide into distilled water several times before placing the leaf pieces.
    I say this because when in the past I have tried the various photosynthesis experiments with pond weed and algal balls, this has worked. I do not use any chemicals in the water as this eventually kills the plant. By saturating the distilled water with carbon dioxide promotes the plant to give off oxygen. I have also used daylight bulbs with some success. However I have not tried your particular experiment yet.
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    User: SWatson

    We did this last year using spinach leaves with some success. Have you put a few drops of liquid detergent per litre of sodium hydrogen carbonate as this is supposed to prevent the leaf discs from sticking together? We have also invested in some brighter halogen lamps (120W) which have proved very effective for pond weed experiments but I have yet to try them with this one. (according to the SAPS website these do work for this experiment). Hope this helps a bit! I know how frustrating photosynthesis experiments are! Good luck.
  5. archive

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    User: Jaymeen

    Have you bought these halogen lamps from Sci chem and are they expensive!I would like to try with pondweed experiment as you suggested.
  6. archive

    archive Administrator Site Admin

    User: SWatson

    We bought the lamps online have them (150W portable halogen lamps) for £9.29 each (the price reduces depending on the number you order).

  7. Hi. We are going to do this experiment on Monday in 4 periods. Can you please suggest how to pass carbondioxide into distilled water?(never done it before)
    Also, do we have to use distilled water? We did this with tap water and sodium bicarbonate last year.
  8. I usually just dissolve some bicarbonate in water and tap water is fine but leave it to stand overnight or put a few drops of thiosulfate in it to neutralise the chlorination.

    I did have trouble with this once where the teacher left the disks in the syringe which stopped them floating.
  9. jan


    We also use to do this but only worked a few times and teachers got fed up of doing it. Best leaves I found were cress and easy to cut off stems.
    We have taken it out of scheme now.!

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