(e) describe how the effects of pH, temperature, enzyme
concentration and substrate concentration on enzyme activity
can be investigated experimentally;
1.
Make up 20cm3 of each hydrogen peroxide dilution using
the instructions in the table below.
2.
Put 10cm3 of each hydrogen peroxide dilution into six new
tubes. LABEL the tubes appropriately.
3.
Set up the measuring cylinder and trough as shown in the
diagram.
4.
Put 1cm3 of catalase into the first boiling tube and insert the
bung with delivery tube.
5.
Start the stop clock.
6.
Measure and record the volume of gas produced at 20
second intervals.
7.
Repeat with each concentration of hydrogen peroxide.
Tube
Volume of H2O2 (cm3)
Volume of H2O (cm3)
A
20
0
B
16
4
C
12
8
D
8
12
E
4
16
F
0
20
Concentration of H2O2 (vol)
Volume of O2 collected in 20 second intervals (cm3)
Conc. of H2O2
(vol)
20
40
60
80
100
120
140
160
180
For the PAG
• Title
• Write up last lesson’s results in table then write ‘due to
low concentration of catalase in the potato we couldn’t
collect a large volume of oxygen we therefore modified
the experiment with the following method:
– Replaced the potato with 1cm3 of 1% catalase
– Added 20 cm3 of each H2O2 concentration to a boiling tube
– Concentrations of H2O2 used: 20vol, 16 vol, 12 vol, 8 vol, 4
vol, 0 vol
The rest of the method was the same as the practical
sheet’
• Then write up today’s results table
Concentration of
H2O2 (vol)
Initial rate of reaction
(cm3 O2 min -1)
Mean initial rate of reaction
(cm3 O2 min -1) (class data)
0
0
4
2.3
8
3.5
12
9.5
16
12.0
20
24.7