Required Practical 10: Decay (T)

• What is the main objective of the practical described in the video?

  Investigate temperature's effect on milk decay
• Why does milk sour when left at room temperature?

  Bacteria produce acidic molecules during decay
• What enzyme is used to model decay in the experiment?

  Lipase
• What does the indicator cresol red indicate in the experiment?

  It changes color based on acidity
• What color does cresol red turn in acidic conditions?

  Yellow
• What is the initial color of the solution before adding lipase?

  Purple
• What is the first temperature used in the experiment?

  20 degrees Celsius
• What is the independent variable in this experiment?

  Temperature
• What is the dependent variable in this experiment?

  Time taken for milk to turn yellow
• What are the control variables in the experiment?

  Volumes of all solutions used
• Why is it important to use a clean test tube for each experiment?

  To avoid triggering reactions prematurely
• How can the timing issue of color change be minimized?

  By sharing data and calculating a mean
• What happens to enzyme activity at lower temperatures?

  Reactions occur slowly
• What is the optimum temperature for enzyme reactions?

  The temperature at which reactions are fastest
• What happens to enzymes at temperatures higher than optimum?

  They denature and may stop working
• How do decomposing microorganisms behave in warm conditions?

  They work faster but not in hot conditions
• What is the effect of high temperatures on microorganisms' enzymes?

  Enzymes denature
• Where can students find additional questions on this practical?

  In the vision workbook