PAG 4: enzyme-controlled reactions

• word equation for the action of a catalase

  hydrogen peroxide -> water + oxygen
• how is the rate of catalase activity indicated?

  by measuring the volume of oxygen gas released in a fixed time
• what is the function of potato in this practical?

  it provides the source of catalyse
• state the independent variable of this practical and how it is varied

  • concentration of hydrogen peroxide
  • by making a simple dilution through mixing with distilled water in the correct proportions
• state the controlled variables in the practical

  • temperature
  • pH
  • volume of hydrogen peroxide solution
  • time allowed to measure gas volume
  • length and width of potato discs
• how is the apparatus set up to measure the volume of gas produced?

  1. fill a trough with water
  2. invert a measuring cylinder and place in the trough, and make sure it is full of water
  3. connect the measuring cylinder to a conical flask with a delivery tube
• why must the bung connecting the conical flask and measuring cylinder be airtight?

  so that all the has produced by an enzymatic reaction displaces the water in the measuring cylinder
• how is rate of reaction calculated?

  rate of reaction = volume of gas produced / time
• state the hazards and safety precautions involved in this practical

  • hydrogen peroxide is an irritant, wear safety goggles and avoid contact with skin
  • take care when handling the sharp cork borer and scalpel