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Anaerobic respiration occurs in conditions of limited
oxygen supply or in the absence of oxygen.
During anaerobic respiration, the glucose is not fully
oxidised to carbon dioxide and water but partly
disintegrates into ethanol and carbon dioxide in
C6H12O6 --------------> 2C2H5OH + 2CO2 + 2ATP
What are the important ingredients do you need to make a bun?
What makes the dough expand and becomes bigger?
How to control the bun expand and becomes bigger in the
Glucose and yeast
1. Measure 4 grams of yeast by the electronic balance.
2. Prepare 3 different concentration of glucose solutions as follows:
5%, 10% and 15%
3. Boil all the glucose solutions under the Bunsen flame to
evaporate any dissolve oxygen in the solution.
4. Cool down the glucose solutions by the ice to prevent the heat
produced killed the yeast during the fermentation.
5. Connect the carbon dioxide sensor with the Data Logger.
6. Mix the glucose solutions with the yeast in the reagent bottle
under the water bath with temperature 30oC.
7. Add a layer of oil on the top of the solutions to prevent gas trap
on the solution.
8. Seal the carbon dioxide sensor to the reagent bottle of the
9. Put the reagent bottle under the water bath for 10 minutes.
10. Record the amount of carbon dioxide at each 10 second
Graph of Amount of CO2 Produced Versus Time
1. Look at your table ,why does the carbon dioxide level
2. Base on the graph, which fermentation of glucose
produced higher amount of carbon dioxide gas? Why?
3. Calculate the rates of respiration of each concentration of
glucose by using the formula given below.
4. What can you conclude from this experiment?
Rate of respiration =
Final reading- initial reading
1. The change of carbon dioxide level indicated that the yeast fermentation of
glucose have begun. Or anaerobic respiration has initiated by yeast.
2. In the same period of time, fermentation of yeast in glucose 5% have
produced higher amount of carbon dioxide. This can be explain as in high
concentration of glucose such as 10% and 15%, the increase in glucose
concentration led to in the increase in fermentation time. Besides, when
the glucose content increased, the glucose uptake rate decreased, this will
affect the rate of fermentation. Thus, as longer time is required for
fermentation of yeast to occur, it have reduced the amount of CO2
produced for both 10% and 15% of glucose fermentation.
4. Fermentation of different concentration of glucose will have different rate
of fermentation and different amount of end product in fixed time.
In the production of fruit wine, most fruits have
natural sugar in them and without adding extra
sugar, these can be turned into a wine of about 4%
to 6% volume alcohol. This is a low alcohol content.
How high alcohol content of fruit wine is produced?
Unique Feature of This Activity
1. Amounts of carbon dioxide produced can be detected and
measured accurately. We can measure in every 10 seconds and
the data can be recorded up to three decimal places.
2. Less work need to be done by the students. For example,
students do not need to be with the experiment all the time as
the results will be recorded automatically during that period of
3. The pattern of amount of CO2 production changes can be
observe along with the experiment.
4. The changes of the data in table and graph can be observed
immediately, allowing us to halt and repeat the experiment