My aim is to find how temperature affects the rate of anaerobic respiration in yeast.

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Tom Gulden

4H

Biology coursework

Anaerobic respiration in yeast.

Aim

My aim is to find how temperature affects the rate of anaerobic respiration in yeast.

Plan

I wish to make my experiment as safe as possible so I will be wearing safety goggles at all times so as not to have any yeast in my eyes.

I know that during anaerobic respiration in yeast CO2 + alcohol are given off. I know this because I carried out an experiment in the 3rd form to see what was given off in anaerobic respiration in yeast. We also learned in this experiment that the alcohol is toxic to the yeast and the yeast will die if too much alcohol is produced. I will measure how much CO2 gas is given off during a specified amount of time to ensure that the alcohol does not affect the yeast and to see how fast the rate of anaerobic respiration is occurring. I have also learnt from my 3rd Form experiments that anaerobic respiration in yeast is an enzyme-controlled reaction. I also know that temperature and pH affect the enzyme-controlled reactions. I have chosen temperature because it is hard to mix acids to the right pH and I can set water baths at to degrees difference to prove the Q10 effect. There are three methods I could use to find the amount of gas that is given off in this experiment. They are:

1.        Collecting the CO2 using a gas syringe.

20cm3 of yeast with a layer of paraffin oil above it are placed in a test tube. The test tube then has a gas syringe connected to it by a delivery tube.

2.        Count the bubbles of CO2 that run through the yeast.

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Set up the same test tube as above accept without a bung or a gas syringe

3.         Collect CO2 using a fermentation tube.

The problems with these experiments are:

Syringe:

  • It is relatively complex to set up so errors may occur in the readings.
  • Air may become trapped between the oil and the yeast making the reaction aerobic.

Bubbles:

  • The person could miss-count the bubbles.
  • The bubbles may be of different sizes.
  • Air may become trapped between the oil and the yeast making the reaction aerobic.

Fermentation tube:

  • It ...

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