Need help with fermentation investigation!

[Coraleen212]

Need help with fermentation investigation!

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Post by Coraleen212 » Sun Nov 27, 2005 8:07 pm

Hey, this is the first time I'm posting here and I'm wondering if anyone can help me with a problem that's come up for my A2 level coursework. Technically it's biology but I guess it's part chemistry as well. Any suggestions greatly appreciated ^_^

I'm doing an investigation on how using various sugars as respiratory substrates alters the rate of fermentation To collect the results I am connecting the reactions up to limewater and then measuring the pH change caused by the production of carbon dioxide. My teacher said that I needed from this to work out the amount of carbon dioxide produced but I'm not sure how to work this out from pH change. Any ideas? Is there a simple(ish) equation I can use to work out amount of CO2 produced from pH change in limewater? So far I have been unable to find such an equation (if it exists XD) but any suggestions or ideas would be greatly appreciated as I have had little luck on this so far Thanks in advance for any ideas ^_^

[catwhoplaysguitar]

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Post by catwhoplaysguitar » Sun Dec 04, 2005 11:45 am

I've got the same investigation, but I'm using a side arm boiling tube connected to a gas syringe (inverted measuring cylinder full of water in a tray full of water will work as well) and I'm directly measuring the amount of CO2 produced.
My problem is the Background Knowledge, What does the yeast do to the lactose and sucrose to be able to respire them. I know it involves enzymes, but I can't find which one/s.

[Coraleen212]

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Post by Coraleen212 » Thu Dec 08, 2005 10:14 am

A lot of people in my group are doing the experiment the way you described - I think I'm the only one doing it this way (on the teacher's recommendation I might add) and now am confused about how to use these pH values to work out carbon dioxide produced. I might have to just analyse the pH values that I have as she said I could do this but it would be better if I could find a way to work out CO2, which have proved nigh on impossible so far XD
As to the theory, I need to check up on that some more as I'm sure enzymes are involved in breaking down the larger sugars I'm just not sure which ones >.> Well if you find out more about this or about the pH -----> CO2 problem please let me know! Much appreciated

[scottyiu]

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Post by scottyiu » Thu Dec 08, 2005 11:36 am

Here is some stuff about sugars:

about3588.html

[Coraleen212]

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Post by Coraleen212 » Fri Dec 09, 2005 10:28 am

Thanks for that scottyiu
Well anyway I've decided to try to analyse these pH values as it seems trying to convert them to CO2 values has proved impossible >.> Or at least, at this level anyway
I was also I little confused as to the enzymes involved. Are enzymes just needed to break down the di/polysaccharides, or do they have some further function in anaerobic respiration itself? Getting slightly mixed up over this - can someone clarify please?