RP: Enzymes (B.5)(B.45)

• What is independent variable?

  pH of buffer solution
• what is the dependent variable? (for this experiment)

  time taken for starch to break down into simple sugars (iodine solution to turn from black to brown)
• 5 control variables

  1)Volume of starch solution 2)temperature of solution 3)how the mixture is stirred 4)Volume of amylase solution 5)Time intervals
• What piece of equipment is used to place the test solution in?

  spotting tile
• how is the temperature controlled?

  using a water bath
• name one risk and precaution

  iodine is an irritant so avoid contact with skin
• how do you know when all of the starch is broken down?

  samples of solution in the spotting tiles turn back to orange/brown
• how can accuracy of the measurements be improved?

  1)Remove the first drop of solution as soon as the amylase is added 2)Use a pipette to measure each drop accurately 3)Start the timer immediately
• why must the solution be constantly mixed

  To ensure that all of the amylase and starch bind to each other
• name one random error

  Different sizes of drops of solution added to the spotting tile
• what has happened to amylase below pH6 and above pH 7?

  Amylase has denatured
• how will the results be displayed?

  plotting a graph of pH against rate
• what results should you see?

  A curve with the rate reaching an optimum at approximately pH7
• what are possible variations on this method?


  1)Investigating the effect of pH on any other enzyme 2)Investigating the effect of temperature on any enzyme