Ozanalp Eryılmaz
11/B
EXPERIMENT: THE EFFECT OF ENZYME
CONCENTRATION ON THE ACTIVITY OF CATALASE
DESIGN
Aim
To investigate the relationship between the enzyme concentration and the activity of catalase.
Research Question
How does the rate of oxygen production by the decomposition of hydrogen peroxide vary
with the increasing concentration of the enzyme catalase?
Hypothesis
The rate of oxygen production increases as the concentration of the micro-organism yeast,
which is the source of the enzyme, increases.
Variables
Independent Variable: Concentration of yeast
Dependent Variable: Rate of oxygen production
Controlled Variables: Volume of hydrogen peroxide, mass of hydrogen peroxide,
temperature and pressure
Apparatus

Instant dry yeast

Measuring cylinder

Boiling tube

Delivery tube
Ozanalp Eryılmaz
11/B

Stopper

Pipette

5 cm3 hydrochloric acid

100 cm3 beakers

Stopwatch
Warning
Hydrogen peroxide may cause burns to skin and clothing. Wash off any spillages using plenty
of water.
Method
1. Stir the yeast and place in the boiling tube.
2. Put the stopper into the boiling tube but do not place the delivery tube under the measuring
cylinder yet.
3. Fill the syringe with 1 ml 10% hydrogen peroxide and attach to the syringe needle.
4. Add the hydrogen peroxide to the yeast suspension. Place the delivery tube under the measuring
cylinder and start a stopwatch.
5. Record the volume of oxygen collected every minute until no more is produced or until the
measuring cylinder is full.
6. Repeat with different concentrations of yeast. (Maximum 2 gr of yeast)
7. Record your results in a table.
8. Calculate the rate of oxygen production for each concentration and plot your results as a graph.
Ozanalp Eryılmaz
11/B
DATA COLLECTION AND PROCESSING
Mass of yeast /
g
0.25
0.50
0.75
1.00
1.25
Initial volume /
cm3
50
50
50
50
50
Final volume /
cm3
62
69
77
87
93
Volume
difference / cm3
12
19
27
37
43
50
45
40
35
30
Amount of Enzyme (g)
25
Volume Difference
(cm3)
20
15
10
5
0
1
2
3
4
5
CONCLUSION AND EVALUATION
Hydrogen peroxide breaks down into water and oxygen with the help of catalase.
Yeast, containing the enzyme necessary for the reaction to take place, in the experiment
catalyses this redox reaction. When the concentration of yeast was increased, the rate of
oxygen production increased as well. Therefore, it can be concluded that the enzyme
concentration is directly proportional to the rate of oxygen production.
In the experiment, there could be inaccuracy caused by a number of experimental
errors. First of all, the temperature of the boiling tube, in which yeast was placed, was not
measured. A thermometer (with an uncertainty of 1°C) should be used to record whether the
Ozanalp Eryılmaz
11/B
temperature of the boiling tube is kept constant throughout the experiment. Besides, a pipette
(with an uncertainty of 0.5 cm³) was used to measure the volume of hydrogen peroxide and a
measuring cylinder (with an uncertainty of 1 cm³) to record the volume of oxygen collected.
Finally, a stopwatch was used to record the rate of oxygen production and it has an
uncertainty of about 0.2 s due to human reaction time at the start and stop moments. These
random errors can be minimised by making use of the equipment with more precision.
Repeating the experiment several times (at least five times) is a suitable solution to decrease
human error as well.