Wednesday, 15 May 2013

5.6 describe a simple experiment to investigate carbon dioxide production by yeast, in different conditions

Have a test tube of yeast in glucose solution. Put a layer of oil on top if you want the yeast to respire anaerobically (as it will prevent oxygen entering the solution.)

Put the test tube in a water bath, heat the water to vary the temperature.

Collect gas coming off in a tube then: count the bubbles; use downwards displacement.


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17 comments:

  1. Unknown17 February 2014 at 09:23

    * Put
    :)

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  2. Unknown8 April 2014 at 02:46

    If the O2 can't get through the oil, the CO2 wont either

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    1. James Grigg18 May 2014 at 09:31

      This comment has been removed by the author.

      Delete
    2. HannahHelp24 May 2014 at 09:02

      Thats why you use downwards displacement- the tube is under the water so the gas can move into it without having to go past the oil :)

      Delete
  3. Anonymous11 April 2015 at 06:27

    You can put the collected gas in limewater, if carbon dioxide is present then it will turn the limewater milky white for people still unsure about it. Thanks for the blog by the way, has helped me so much.

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  4. Anonymous26 October 2015 at 23:30

    This comment has been removed by the author.

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  5. Anonymous26 October 2015 at 23:32

    i would suggest you to use a lid to prevent oxygen entering instead of oil because sometimes things can react or change with oil added (making the test unreliable)

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    1. Anonymous5 May 2016 at 05:55

      incorrect, you don't need to worry about that in IGCSE

      Delete
  6. Anonymous4 November 2015 at 08:47

    your blog has saved me

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  7. Anonymous10 May 2016 at 12:09

    This comment has been removed by the author.

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  8. Anonymous10 May 2016 at 12:12

    Add glucose solution to a conical flask
    Add dried (killed) yeast to the test tube and stir
    Add 1/2 drops of oil to ensure that oxygen can't interfere with the reaction (making it anaerobic)
    Seal the conical flask with one end of the delivery tube
    simultaneously, invert a test tube filled with water with your thumb sealing the test tube into a beaker of water, stick the other end of the delivery tube up the test tube (Do this underwater).
    The carbon dioxide produced will eventually displace most of the water, you can then take out the test tube from the water and seal it with a bung the moment its out of the water.
    add lime water to the test tube as soon as the bung has been removed, whatever water is left in the test tube will turn milky proving that CO2 is release during fermentation.

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    1. Anonymous10 May 2016 at 12:21

      forgot to mention to heat the test tube with the mixture :P by placing the test tube in a water bath.

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  9. Unknown3 January 2017 at 13:01

    Super explanation!

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  10. studentblogger14 January 2017 at 06:26

    Hannah, what did you get for your igcse biology exams?
    Well done on your page, it inspires me to revise better :)

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  11. Unknown25 February 2017 at 03:00

    CORMS explanation?

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  12. SophieRice27 June 2017 at 06:06

    more at

    http://igcse-biology-notes.blogspot.hk/2017/06/56-describe-simple-experiment-to.html

    ReplyDelete

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