Effect of pH on enzyme activity required practical

Question 1

Describe the method

Answer 1

• Drop of iodine solution into each well of a spotting tile
• Bunsen burner on a heat proof mat and a tripod
• Heat a beaker of water to 35°c (use a thermometer).
• Use a syringe to add 1cm³ of amylase solution to 1cm³ of buffer solution with a pH of 5 to a boiling tube. Wait for 5 minutes.
• Add 5cm³ of starch solution to the boiling tube use a different syringe
• Immediately mix the contents of the tube and start a stop clock.
• Continuous sampling to record how long it takes for the amylase to break down all the starch - use a pipette to take a fresh sample from the boiling tube every 30 seconds and put a drop in a well. When the iodine solution remains the same colour, starch is no longer present.
• Repeat experiment with solutions of different pH values (see how pH affects the time taken for the starch to be broken down

Question 2

independent, dependent and control variables

Answer 2

Independent - pH of different solution
Dependent - time taken for the starch to be fully broken down
Control - concentration and volume of amylase solution

Question 3

Which enzyme catalyses the breakdown of starch to maltose?

Answer 3

Amylase

Question 4

How can we detect starch?

Answer 4

By using iodine - if iodine is present, it turns the solution from browny-orange to blue-back

Question 5

How do we calculate rate of reaction?

Answer 5

Rate = 1000/time