Paper 2 - Molecules

Question 1

Describe a practical to investigate how enzyme activity can be affected by changes in pH

Answer 1

• Add a drop of iodine to each of the wells of a spotting tile
• Use a syringe to place 2 cm3 of amylase into a test tube
• Add 1cm^3 of buffer solution (at pH 2) to the test tube using a syringe
• Use another test tube to add 2 cm3 of starch solution to the amylase and buffer solution, start the stopwatch whilst mixing using a pipette
• Every 10 seconds, transfer a droplet of the solution to a new well of iodine solution (which should turn blue-black)
• Repeat this transfer process every 10 seconds until the iodine solution stops turning blue-black (this means the amylase has broken down all the starch)
• Record the time taken for the reaction to be completed
• Repeat the investigation with buffers at different pH values (ranging from pH 3.0 to pH 7.0)