practical

• You can investigate the effect of pH on enzyme activity by detecting starch after enzymes break down food molecules.
• The enzyme amylase catalyses the breakdown of what to what?


  starch to maltose
• How can we detect starch?

  Using iodine solution
• What colour is iodine and what colour will it turn if starch is present?

  brown-orange to blue-black
• How do you investigate how pH affects amylase activity?

  (1) Heat water using a bunsen to 35 degrees

  (2) Use a syringe to add 1cm³ amylase solution and 1cm³ of buffer solution (pH 5) to a boiling tube.

  (3) Put tube in beaker of water for 5 minutes.

  (4) Add 5cm³ starch solution and immediately mix.

  (5) Start stopwatch.

  (6) Sample mixture every 30 seconds by putting on spotting tile with iodine.

  (7) When iodine stays orange-brown starch is no longer present.

  (8) Repeat whole experiment with different pH values
• How do you calculate rate of reaction?

  rate=1000/time
• What are the units for rate of reaction?

  s⁻¹