Enzyme Activity (P1)

• What is the aim of the enzyme practical?

  To investigate how a named variable (pH) affects the rate of an enzyme-controlled reaction
• what are the independent and dependent variables in this practical (P1)

  IV - pH

  DV - rate of reaction
• What is the purpose of repeating the experiment at different pH or temperature levels

  To determine the optimal conditions for enzyme activity and observe how deviations affect the rate and eliminate anomalies
• What are the common enzymes used in investigations?

  Amylase, catalase, protease, and trypsin
• What is the hypothesis for the experiment on trypsin?

  Trypsin will work between pH 4 to 11, optimum at pH 9
• What is the source of the substrate used in the experiment?

  Photographic film
• What color change indicates the reaction of trypsin with the substrate?

  From black opaque to colorless and clear
• What is the first step in the method of the experiment?

  Attach the film to a straw
• Why is the test tube placed in a water bath at 37 degrees Celsius?

  To allow the solution to reach the correct temperature
• What should be done after five minutes in the water bath?

  Start the stop clock and dunk the straw
• What indicates that the reaction has reached its endpoint?

  The film becomes completely clear and colorless
• What should be recorded if there is no change in the film after 25 minutes?

  Record it as infinity or no reaction
• What is the purpose of using a control experiment with water instead of trypsin?

  To prove the pH alone causes the color change
• How should results be recorded in the experiment?

  In a table with three significant figures
• How is the rate of reaction calculated?

  Rate = 1 divided by time taken
• What is the significance of converting results to times $10^{-3}$?


  It simplifies data for easier plotting
• What should be done when plotting data on a graph?

  Ensure the graph fills half the paper
• What determines whether to draw a line of best fit or dot-to-dot?

  Number of data points and clarity of pattern
• What is the conclusion regarding trypsin at pH 4?

  Trypsin was denatured at pH 4
• Why can't the optimum pH be definitively concluded from the experiment?

  Not enough intermediate pH values were tested
• What are some limitations of the method discussed?

  Subjective endpoint, temperature control issues
• What is a common question in paper three regarding practicals?

  Evaluate the method or conclusion
• What does it mean if the water bath is not thermostatically controlled?

  Temperature may decrease during the practical
• Why is it important to identify anomalous results?

  To ensure accurate calculation of the mean
• What should be done if an anomalous result is found?

  Remove it from the mean calculation
• What is the significance of presenting numbers to three significant figures?

  It ensures precision in reporting results
• How does the conclusion relate to the aim and hypothesis?

  It should refer back to the predicted outcomes
• What is the final step in the practical write-up?

  Conclude and evaluate the method
• Why is a control experiment necessary in enzyme investigations?

  To validate that changes are due to pH alone
• How does temperature affect enzyme activity?

  Higher temperatures can increase reaction rates
• Why is a stop clock used in enzyme experiments?

  To accurately measure reaction times
• What is the significance of documenting experimental procedures clearly?

  It allows for reproducibility of the experiment
• How does enzyme concentration influence reaction rates?

  Higher concentrations typically increase reaction rates
• Why is it important to test a range of pH values?

  To identify the optimum pH for enzyme activity
• Why should trials be repeated in experiments?

  To ensure reliability and accuracy of results
• What does denaturation mean in the context of enzymes?

  Loss of enzyme structure and function
• Why is clear communication important in scientific reporting?

  To convey findings accurately to others
• What is the importance of labeling graphs and tables?

  It helps readers understand the data presented