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    I have to do a coursework plan on a yeast respiration experiment plan shortly for AQA A2 biology spec B. Does anyone have any ideas what kind of experiment i would have to carry out, for example i thought it may be something to do with the effect on changing the temperature.

    Also has anyone got any ideas on how you could measure the rate of respiration of yeast in an experiment?

    thanks
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    Test the rate using a gas syringe to measure the amount of gas given off (CO2 I think?) when the sugar is fermented.

    Yup temperature is a good one, or you could do glucose concentration or different sugars such as glucose, fructose and lactose.
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    I did this for my OCR coursework

    Basically

    1. Make up solutions of yeast and glucose (in seperate beakers)
    2. Add an indicator called TTC (it turns pink when respiration is complete, it detects a change in pH when CO2 is formed)

    Method
    1. Set up a water bath (use a bunsen burner for more to talk about in evaluation and analysis, but used waterbath if you want for more accurate results) place a test tube with a little glucose solution. in it to heat up to the same temp as the water. Add TTC then add the yeast and as soon as you add the yeast, start a stop clock. Time how long the solution takes to turn pink. then stop and record the time taken.
    2. Repeat at different temperatures (i used 25,35,45,55,and 65c) and repeat whole experiment 3 times

    This is very vauge. Ask if you need anymore info and pm me if you ever need any help on it
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    I did this for my OCR coursework

    Basically

    1. Make up solutions of yeast and glucose (in seperate beakers)
    2. Add an indicator called TTC (it turns pink when respiration is complete, it detects a change in pH when CO2 is formed)

    Method
    1. Set up a water bath (use a bunsen burner for more to talk about in evaluation and analysis, but used waterbath if you want for more accurate results) place a test tube with a little glucose solution. in it to heat up to the same temp as the water. Add TTC then add the yeast and as soon as you add the yeast, start a stop clock. Time how long the solution takes to turn pink. then stop and record the time taken.
    2. Repeat at different temperatures (i used 25,35,45,55,and 65c) and repeat whole experiment 3 times

    This is very vauge. Ask if you need anymore info and pm me if you ever need any help on it


    Hi, can you tell me what the limitations for this experiment can be and is the TTC used instead of NAD, as a hydrogen acceptor?
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    (Original post by AfricanQueen1)
    What are the limitations for this experiment and is the TTC used instead of NAD as a hydrogen acceptor..thanks in advance
    Oh god this is going back a bit, urm I never did investigate variables coz I used this to do implementation, analysis and evaluation for my c/w, not planning. I'll have a look over it though...

    Also the TTC is just an indicator that changes with pH change, there is still NAD present in the mechanism, I don't rememebr exactly how the indicator works, but I'm guessing its something to do with decreasing pH (more acidic) as dehydrogenation takes place...

    I'll look into that though
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    I'm measuring different concentrations of glucose. I'm going to be using the capillary tube method. You need to have you yeast in a test tube in a water bath (to keep temperature constant). Then you must prepare different concentrations of glucose to mix with the yeast. A capillary tube should have a drop of coloured solution. Once the two mixtures are combined the test tube should be sealed with the capillary tube through the bung. As the yeast respires it will release CO2 and increase the pressure withing the test tube and capillary tube forcing the coloured solution along the tube. Measure the distance the coloured solution travels in a set time and this should give some reliable date, only down side to this is it's tricky to set up but once done it's easy to carry out multiple texts to a high degree of accuracy.
 
 
 
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