
1.10 - Identify data sources, plan, choose equipment or resources and perform a
first-hand investigation to test the effect of:
– increased temperature
– change in pH
– change in substrate concentrations on the activity of named enzyme(s)
1. Title: The Effect of Change in substrate on enzyme activity.
Aim: To look at the effects of changing the amount of substrate on the activity of an
enzyme called rennin in milk.
Method:
1. In groups of three, collect 7 test tubes and label them as test tubes, 1 to 7. Set up the
following:
Test
Test
Test
Test
Test
Test
Test
Tube 1
Tube 2
Tube 3
Tube 4
Tube 5
Tube 6
Tube 7
Milk
3mL
2.5mL
2mL
1.5mL
1mL
0.5mL
0mL
Water
0mL
0.5mL
1mL
1.5mL
2mL
2.5mL
3mL
% Milk
2. Add 0.3g
junket powder in 10mLs of water in a small beaker.
3. Mix the junket solution and add 10 drops to each test tube. Shake each test tube and
record the time.
4. Examine the tubes every 30 seconds for 20 minutes by gently tilting the test tubeDO NOT SHAKE.
5. Record the time it takes for the milk to clot.
Safety Precautions:
Results: Table and Graph
Conclusion:
Questions:
1. Explain how the changes in amount of substrate effects the enzyme activity.
2. What is the purpose of test tube 7?
3. Explain which variables have been controlled?
4. Is this a valid experiment? Explain.
2. Title: The Effect of Change in pH on enzyme activity.
Aim: To look at the effects of changing pH on the activity of an enzyme called rennin
on milk.
Method:
1. In groups of 3, collect 5 test tubes and label them 1 to 5.
2. As a class make up solutions of milk at pH3, pH5, pH7, pH 9 and pH 11 using
0.1M NaOH and 0.1M HCl.
Record any changes to the milk as a result of pH changes.
2. Add 3mL of milk at each pH to test tubes labeled 1-5 as shown.
Test Tube 1
Test Tube 2
Test Tube 3
Test Tube 4
Test Tube 5
pH3
pH5
pH7
pH9
pH11
5. Add 0.3g junket powder to 10mL water in a small beaker.
6. Add 10 drops to each test tube. Shake each test tube and record the time.
7. Examine the test tubes ever 30 seconds for 20 minutes by gently tilting the tubes –
DO NOT SHAKE
8. Record the time it takes for the milk to clot.
Safety Precautions:
Results: Table and Graph
Conclusion:
Questions:
1. Explain how the changes in amount of substrate effects the enzyme activity.
2. What is the purpose of test tube 7?
3. Explain which variables have been controlled?
4. Is this a valid experiment? Explain.
Testing the effect of temperature, pH or substrate concentration on enzyme
activity
Background information
What is renin?
What is its function?
Aim
Method ( use point form and be quite specific. Include safety considerations, use of
control, the variables held constant and a diagram)
Results ( include table and graph if possible)
Discussion ( include possible sources of error, ways of improving validity and
reliability)
Conclusion ( must relate to your aim)