1. +
Anaerobic respiration
Fermentation

2. +
Scientific Concept
Anaerobic respiration occurs in conditions of limited oxygen
supply or in the absence of oxygen.
During anaerobic respiration, the glucose os not fully oxidised to
carbon dioxide and water but partly disintegrates into ethanol and
carbon dioxide in plant cells.
C6H12O6  2C2H5OH + 2CO2 + 2ATP

3. +
Engage

4. + What are the
important
ingredients do
you need to
make a bun?
Question?
How to
What makes
control the
the dough
bun expand
expand and
and becomes
becomes
bigger in the
bigger?
shortest time?

5. +
Empower

6. +
 4 grams of yeast was measured by the electronic balance.
 Glucose solution was prepared in a beaker. Different
concentration of glucose solution was prepared as follows :
 5%, 10% and 15%
 The glucose solution of 5% was boiled under the Bunsen flame
to evaporate any dissolve oxygen in the solution
 This glucose solution was cooled down by the ice to prevent
the heat produced killed the yeast during the fermentation.
 The carbon dioxide sensor was connected with the Data
Logger.

7. +  Glucose solution was then mixed with the yeast in the reagent
bottle under the water bath with temperature 30oC. Water bath
was prepared to maintain the temperature as heat produced
will affect the reaction during anaerobic respiration.
 A layer of oil was added on the top of the solution to prevent
gas trapped in the solution.
 The carbon dioxide sensor healed the reagent bottle of the
mixed solution.
 The reagent bottle was put under the water bath for 10
minutes.
 The amount of carbon dioxide was recorded at each 10
seconds interval.
 Step 4 to 11 are repeated but the concentration of glucose
solution is changed to 10% and 15% respectively.

8. +
Result

15. From the graph and table, it is shown that the fermentation
of 5% of glucose produced the highest amount of CO2
and the highest rate of fermentation. While fermentation of
both 10% and 15% of glucose have produced almost
same amount of CO2 in the same period of time, both also
have steady rate of respiration.
Cencentrati Initial Final Rate of
on of Respiration
glucose (ppm/min)
5% 758.154 5960.923 212.73
10% 590.769 2924.308 122.45
15% 738.462 3042.462 96.72

16. +
Question
 Look at the table, why does the carbon dioxide level change?
 Base on the graph, which fermentation of glucose produced higher
amount of carbon dioxide gas? Why?
 Calculate the rates of respiration of each concentration glucose by
using the formula given below.
Rate of respiration = Final reading – initial reading
Time
(min)

17. +
Answer
 The change of carbon dioxide level indicated that the yeast
fermentation of glucose have begun. Or anaerobic respiration has
initiated by yeast.
 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.

18. +
Discussion
 The fermentation of glucose, which occurs primarily when the
glucose concentration is high or when oxygen is not available.
 The cells have a low energy yield of only about 2 ATP per mole
of glucose metabolized. The stoichiometry of this reaction is
C6H12O6  2C2H5OH + 2CO2 + 2ATP

19. +  The influence of different glucoseby the overall amount of CO2
activities of yeast was evaluated
concentration on metabolic
and rate of reaction.
 In high concentration of glucose such as 10% and 15%, the
increase in glucose concentration led in the increase in
fermentation time.
 Besides, when the glucose content increased, the glucose
uptake rate decrease, 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.
 Conversely, for the same reason which mentioned above,
fermentation of 5% glucose have produced the higher amount
of CO2 and with the highest rate of fermentation.

20. +
Enhance
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?

21. To make a stronger wine about 12% to 17%i
sugar is needed to bring the alcohol content
up to level high enough.
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 whereby it will prolog the
fermentation process, resulting in higher
amount of by-product produces in time.
Thus, producing fruit wine with alcohol
content.

22. +
Unique Feature of this Activity
1. Amount of carbon dioxide produced can be detected
and measured accurately. We can measured 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 result will be recorded
automatically during that period of time.
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 easily.