Decay

• What is the independent variable in the decay practical?

  Temperature
• What temperatures will be tested in the decay experiment?

  15, 30, 45, 60, and 75 degrees Celsius
• Why is phenolphthalein used in the experiment?

  It indicates pH changes in the solution
• What color does phenolphthalein turn in an alkaline solution?

  Pinky purple
• What happens to the color of phenolphthalein as milk decays?

  It decolorizes as pH decreases
• What causes the pH of the milk to drop during the experiment?

  Fatty acids produced from lipid breakdown
• What is the dependent variable in the decay practical?

  Time taken for decolorization
• What enzyme is used in the decay experiment?

  Lipase
• How much lipase is added to the milk in the experiment?

  5 milliliters
• Why is lipase used instead of microbes in this experiment?

  For speed in observing decay
• At what temperature does the first experiment take place?

  60 degrees Celsius
• What is the purpose of using a thermometer in the experiment?

  To ensure correct temperature of the milk
• What happens to the milk's color as lipase breaks down lipids?

  The pink color fades
• What should be done after collecting results at different temperatures?

  Repeat the experiment for accuracy
• How is the mean average calculated in the experiment?

  By averaging the time taken at each temperature
• What graph is plotted after calculating the mean average?

  Temperature on the x-axis, time on the y-axis
• What is the optimum temperature for lipase activity?

  Around 37 degrees Celsius
• What trend is expected in the results regarding temperature and decay rate?

  Faster decay rates at optimal temperatures
• What is the role of sodium carbonate in the experiment?

  To ensure the milk solution is alkaline
• Why is constant mixing important during the experiment?

  To ensure uniform enzyme action
• How does microbial growth affect decay rates?

  Increases decay rates through enzyme production
• Why is a water bath used in the experiment?

  To control the temperature of the milk
• What is the significance of having a control variable?

  To ensure fair testing conditions
• What results are expected at different temperatures?

  Similar results to previous enzyme experiments
• What relationship is expected between enzyme activity and temperature?

  Increased activity at optimal temperatures