practical 2

• On a tile, label each well with the time (from 0 onwards) and add a drop of iodine solution to each well.
• Prepare a range of temperatures of water baths (from 20 to 60°C) at fixed 10°C intervals.
• Transfer 3 cm3 of amylase into a labelled test tube and place in a water bath.
• Transfer 3 cm3 of starch solution into a labelled test tube and place in the same water bath.
• Allow time (a few minutes) for the temperature to equilibrate, then mix the 2 solutions together by stirring with a glass rod and start timing immediately.
• Use the glass rod to transfer a drop of the mixture to the well labelled ‘0’ on the tile.
• Repeat step 6 every minute, rinsing the glass rod in between every test, until the iodine solution remains brown and does not turn blue-black.
• Record results in a table as seen below.
• Calculate the rate of enzyme reaction by using 1/ time taken for iodine solution to remain brown.
• Repeat steps 2-8 for other temperatures of water baths.
• Plot a graph of the rate of enzyme reaction against temperature.