Required practical 5: Enzymes

• Step 1: Place one drop of iodine solution into each well of the spotting tile
• Step 2 : gather 3 test tubes, in the first test tube add 2cm^3 of starch solution in the second test tube add 2cm^3 of amylase solution, in the third test tube add 2cm^3 pH 5 buffer solution
• Step 3: place all three test tubes in a water bath at 30 degrees for 10 minutes to allow the solutions to reach the same and correct temperature
• Step 4: Combine three solutions into one test tube and mix with a stirring rod. Return to the water bath and start a stopwatch
• Step 5: After 30 seconds use the stirring rod to transfer one drop of solution to a well in the spotting tile which contains iodine
• Step 6 : take a sample every thirty or twenty seconds and continue until the iodine remains orange
• When iodine remains orange, this tells us that starch is no longer present
• Step 7: Repeat the whole experiment several times using different pH buffers
• improve experiment

  1. use smaller intervals for continuous sampling
  2. ask many people to observe colour change (as it is subjective)