Thursday, February 23, 2012

IB Biology, Enzymatic decomposition of hydrogen peroxide by enzyme catalase

IB Biology on Enzymatic decomposition of hydrogen peroxide by enzyme catalase using disc and well method
Simple enzymatic study (Inaccurate)
  • Place 5ml hydrogen peroxide into well
  • Soak paper disc in well containing catalase
  • Place disc soak with catalase into well
  • Measure time for disc to float
  • H2O2 decomposes - produce O2
  • O2 will cause the disc to float
  • Rate = Time taken for disc to reach the surface


Video tutorial on decomposition of hydrogen peroxide using Disc method



Sample report for SL Biology using disc method

Accurate Method for Enzymatic study measured using Pressure or Oxygen sensor

  • Rate of decomposition = Change in pressure due to release of O2 gas released over time
  • Pressure sensor or Oxygen Sensor can be used
  • Initial rate will have to be used







Click here to view video on decomposition of hydrogen peroxide using pressure sensor
  • Make sure it is time based for 300s
  • Press collect button to obtain the base line pressure
  • Add catalase enzyme
  • Close cap and measure pressure



Tip when using Pressure sensor
  • Always collect the average rate for first 50s
  • Use linear regression to find the gradient for first 50s
  • If possible take instantaneous rate at time zero (Initial Rate)
  • Initial rate (time close to zero) is used because as time progresses, conc of H2O2 changes
  • To measure rate at certain H2O2 concentration - Initial rate must be use



Sample report on hydrolysis of starch using pressure sensor

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