Yeast and hydrogen peroxide

Discussion in 'Supporting Biology' started by ClaireS, Jul 4, 2019.

  1. I have a teacher here asking me to trial something she has seen on the net - she has no method or anything - she just says you add yeast powder to hydrogen peroxide in a test tube and measure the foam...she says it needs nothing else and maybe we could change the amount of yeast to be added to give some sort of a meaningful practical with a range of results...My question is has anyone done something like this and is there a method I could at least get ideas from??? I have tried looking it up on the net but seem to just get lots of one off - just add yeast to peroxide demos with no measuring of anything involved....I can't seem to get the enthusiasm to trial a practical she can't be bothered to write a method for........Any ideas anyone??
  2. Hello Claire, we sometimes do this with chunks of liver, potato and apple each put into 10ml of 20 vol peroxide in boiling tubes and measure the height of foam produced - just to show there are different levels of catalase in these samples. If powdered yeast doesn't froth then maybe make a solution - we do a more sophisticated experiment for A level using a yeast solution with peroxide and measuring the rate of O2 production at different temperatures.
    Last edited: Jul 4, 2019
    ClaireS likes this.
  3. the yeast contains catalase which breaks down the h2o2, so it's an enzyme concentration experiment, you can do it with gas syringes or collect the gas over water as a rates practical.

    or substitute potato as a source of the enzyme.
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  4. Shannon

    Shannon Shannon COMMITTEE

    I know this sounds odd - but we have Year 8's in the last few weeks basically plan their own praticle (currently watching some in the food room) & one of ours did this and sounded like it worked?

    They had 20vol Hydrogen peroxide, Potassium Iodide and Yeast... not fully sure on the outcome of this one?? But I know it works fine
    ClaireS likes this.
  5. We used to do this too, used gas syringes to collect,well, gas!
    Do something similar with lower years in measuring cylinders. Mark where you start from etc.
    ClaireS likes this.
  6. Yeast can be used in Elephants Toothpaste too. Not such a violent reaction as Potassium Iodide.
    20 Vol upper limit we use usually.
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  7. Used to do it year in, year out.

    5vol H2O2 in a 250ml measuring cylinder (think it was 10ml H2O2) and vary mass of yeast (think max used was a gram).
    ClaireS likes this.
  8. Hi Claire,
    I do this using fast action yeast. It's the same experiment as people do with ground liver, celery or potato, but it is clean and easy with the dried yeast and a version of elephant's tooth paste as people have said above. You can find a full written method and risk assessment information on Nuffield Practical Biology here
    I sometimes do it in a small conical flask - just add a spatula of yeast to the hydrogen peroxide. Enough oxygen accumulates in the bottle neck to relight a glowing splint.
    You can also do a 'microscale' version using more dilute hydrogen peroxide if you make up a yeast suspension and either dip filter paper discs in yeast solution or trap yeast suspension in sodium alginate beads. When you drop the discs/beads into the H2O2 they sink until they make enough oxygen to float back up again. It's good fun so might be a good thing to do as it gets near the end of term. See SSERC activity Effervescent enymes. The teacher/tech notes can be found here
    ClaireS likes this.
  9. Yep biology_owl I would go with the alginate beads with varying concs of H2O2. Less messy and more entertaining for the kids. We moved to this method a couple of years ago.
    Beaker likes this.
  10. greenfingers

    greenfingers Sarah G

    add a drop of washing up liquid for the foam
  11. Yep this is our Yr10 induction activity, day 4 tomorrow, just stirring my alginate now.

    Used to finish this practical with an exploding liver demo [outside less mess to clean up]

    Alex Craig and ClaireS like this.
  12. Haven't done yeast -that's more dough (respiration.) which rises in measuring cylinders. Do similar for H2O2/catalase as mentioned previously using potato, boiled potato, liver etc. Is she wanting respiration or enzyme practical..?! I'm confused!
  14. Hi,

    how far in advance can you prepare the yeast alginate balls please. Also what % of hydrogen peroxide do you use?

    Many thanks