AQA GCSE FOUNDATION Biology: Investigating Enzyme Activity

AQA GCSE Foundation Biology: Investigating Enzyme Activity

This tutorial will guide you through a practical investigation of enzyme activity, specifically focusing on the enzyme amylase and its breakdown of starch. You will learn how to:

• Observe enzyme-substrate reactions.
• Determine the optimal conditions for enzyme activity.
• Calculate the reaction rate.

Materials:

• Amylase solution (e.g., from saliva or commercially available)
• Starch solution
• Iodine solution (for starch detection)
• Test tubes
• Beakers
• Measuring cylinders
• Pipettes
• Water baths (for temperature control)
• Stopwatch
• Graph paper

Procedure:

1. Setting up the Experiment:

• Label test tubes with different conditions (e.g., different temperatures, pH levels).
• Fill each test tube with a measured volume of starch solution.
• Prepare separate solutions of amylase with appropriate volumes for each condition.

2. Controlling Variables:

• Temperature: Use water baths to maintain the desired temperature for each test tube.
• pH: Use buffers to maintain the desired pH level for each test tube.
• Concentration: Ensure the same concentration of amylase and starch is used for each test tube.

3. Starting the Reaction:

• Add the amylase solution to the starch solution in each test tube simultaneously.
• Start the stopwatch immediately.

4. Observing the Reaction:

• At regular time intervals (e.g., every 30 seconds), remove a small sample from each test tube using a pipette.
• Add a drop of iodine solution to each sample.

• Observe the color change:

  • Blue-black: Starch is present.
  • Yellow-brown: Starch has been broken down by amylase.

5. Recording Data:

• Record the time taken for the starch to be completely broken down (indicated by a yellow-brown color) for each condition.
• Repeat the experiment at least three times for each condition to ensure accuracy and reliability.

6. Calculating the Reaction Rate:

• Reaction rate = 1 / Time taken for starch to be completely broken down

  • For example, if it takes 60 seconds for the starch to be completely broken down, the reaction rate would be 1/60 = 0.0167 per second.

7. Analyzing the Results:

• Plot the reaction rate against the varying conditions (e.g., temperature, pH).

• Analyze the graph to determine:

  • The optimal condition for amylase activity.
  • The effect of temperature and pH on enzyme activity.
  • The relationship between enzyme efficiency and the optimal condition.

Conclusion:

• Summarize your findings based on the data analysis.
• Discuss the relationship between enzyme activity, temperature, and pH.
• Explain the significance of optimal conditions for enzyme activity.
• Relate your findings to the biological processes that involve amylase.

Note:

• Always handle chemicals with care and wear appropriate safety goggles.
• Dispose of all materials properly according to your school's safety guidelines.

By following these steps and analyzing your results, you will gain a deeper understanding of enzyme activity and its importance in biological processes.