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    Hey all

    Just have a few questions on photosynthesis, if anyone could help?

    1.How does the wavelength effect the rate of reaction?, Is it just that some light (ie green) is reflected, but others are absorbed. Therefore more photons are absorbed, or am i being stupid?

    2.If i was to do this experiment using a photosynthometer, what would i use as a control?

    2a. would i need to add more sodium hydrogencarbonate as it get used up?

    any help would be appreciated
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    (Original post by petoid12)
    Hey all

    Just have a few questions on photosynthesis, if anyone could help?

    1.How does the wavelength effect the rate of reaction?, Is it just that some light (ie green) is reflected, but others are absorbed. Therefore more photons are absorbed, or am i being stupid?
    Hey, usually you have to work this out, which is why you are doing the experiment in the first place. Green light would mainly be reflected because green is the colour of the photosynthetic pigments. Different plants photosynthesise differently, also you have to think about the fact that different antenna complexes absorb specific wavelengths.
    (Original post by petoid12)
    2.If i was to do this experiment using a photosynthometer, what would i use as a control?
    My control would be the exact same set up, but with no plant, just to make sure that you don't record any photosynthesis occuring. Clearly if there was no plant and photosynthesis was being recorded, then it is not a fair test and there are confounding variables which are not being controlled.
    Spoiler:
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    A control experiment is one that is set up to eliminate certain
    possibilities. In a well designed investigation, the independent
    variable is changed and all confounding variables are kept
    constant. The possibility exists, however, that something else other
    than the independent variable might have produced the results that
    were obtained. A control experiment is one that is designed to
    eliminate this possibility.


    (Original post by petoid12)
    2a. would i need to add more sodium hydrogencarbonate as it get used up?

    any help would be appreciated
    I would say no, because then different plants/experiments will get sodium hydrogencarbonate at different times, and this can effect the rate of photosynthesis. As long as they each get the same volume at the start of the experiment that should be fine.
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    Is this ISA/EMPA related?
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    (Original post by Revd. Mike)
    Is this ISA/EMPA related?
    I don't think so, we done a practical at the start of A2 on this sort of thing and it came up in the unit 4 exam(AQA). Although it could be, I hope not, I don't want to encourage cheating
 
 
 
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