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)