Investigation enzymatic reactions

• What is the focus of the investigation described in the study material?

  The effect of pH on enzyme activity
• What is the practical method to investigate the effect of pH on enzyme activity?

  • Use iodine solution to detect starch breakdown
  • Prepare a water bath at 25°C
  • Mix amylase and buffer solution in a boiling tube
  • Add starch solution and start timing
  • Sample every 30 seconds until starch is no longer present
  • Vary buffer solutions to test different pH levels
• How do you maintain the temperature during the enzyme activity experiment?

  By placing a beaker of water on a tripod over a Bunsen burner
• What is the purpose of using a dropping pipette in the experiment?

  To take fresh samples from the boiling tube
• What does the iodine solution indicate in the experiment?

  It changes color from brown to blue-black in the presence of starch
• Why is it important to control variables in the enzyme activity experiment?

  To ensure a fair test and accurate results
• What is the formula to calculate the rate of reaction?


  Rate = $\frac{change \, in \, amount}{time}$
• If the time taken for amylase to break down starch is 90 seconds, what is the rate of reaction?


  Rate = $\frac{1000}{90} \approx 11.11 \, cm³/s$
• How do you calculate the rate of reaction for the enzyme catalase breaking down hydrogen peroxide?


  Rate = $\frac{24 \, cm³}{50 \, s} =$$0.48 \, cm³/s$
• If an enzyme-controlled reaction at pH 4 produces 36 cm³ of product in 2 minutes, what is the rate of reaction?

  Rate = $\frac{36 \, cm³}{120 \, s} =$$0.3 \, cm³/s$
• What factors can be investigated to affect the rate of amylase activity?

  • pH levels
  • Temperature variations
  • Concentration of substrate
  • Concentration of enzyme