Core Practical 1

• Core Practical 1: Title

  Effect of substrate concentration on the rate of an enzyme controlled reaction (catalase on hydrogen peroxide)
• Core Practical 1: Equipment required

  -graduated pipette-sieve-ruler-stop clock-watch glass -specimen tube-potato extract-hydrogen peroxide (2, 4, 6, 8, 10, 12, 14, 16, 18, 20 vols)
• Core Practical 1: Method

  1- use graduated pipette to measure 5ml of hydrogen peroxide (2 vols) into a specimen tube2- measure height with ruler to make sure height is the same throughout each test3- use forceps to soak small paper disc in potato extract for 5 seconds (time on stop clock)4- blot paper on watch glass to remove excess5- use forceps to place paper at bottom of specimen tube6- start stop clock as soon as paper touches hydrogen peroxide 7- stop timer as soon as disc reaches surface of hydrogen peroxide 8- repeat this for all concentrations of potato extract 9- repeat whole process 3 times and record on table
• Core Practical 1: Variables

  Independent = concentration of substrateDependent = time taken for disc to reach surface if hydrogen peroxideControls = size of paper disc, time disc is soaked for, height of hydrogen peroxide
• Core Practical 1: Risks

  -glassware (can cut skin if broken)-hydrogen peroxide (irritant- can irritate skin and eyes)-forceps (points can cut skin)