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C1.1.6—Role of molecular motion and substrate-active site collisions in enzyme catalysis


Here are experiments our science specialists have selected to support this IB* topic.

Testing Enzyme Activity (Spectrometer)

Experiment #6C from Investigating Biology through Inquiry

  • Identify variables, design and perform the investigation, collect data, analyze data, draw a conclusion, and formulate a knowledge claim based on evidence from the investigation.
  • Determine the rate of the peroxidase catalyzed reaction converting H2O2 to H2O and O2.
  • Gain increased understanding of factors affecting peroxidase activity.

Testing Catalase Activity (O2 Gas Sensor)

Experiment #6A from Investigating Biology through Inquiry

In this Preliminary Activity, you will use catalase in yeast to catalytically decompose hydrogen peroxide. You will use an O2 Gas Sensor to determine the rate of catalase activity by measuring oxygen gas produced as H2O2 is decomposed.

At the start of the reaction, there is no product, and the O2 concentration is the same as the atmosphere. Shortly after data collection begins, oxygen accumulates at a rather constant rate. The slope of the curve at this initial time is constant and is called the initial rate. In this investigation, we will refer to this as the rate of catalase activity. As the peroxide is decomposed, less of it is available to react and the O2 is produced at lower rates. When no more peroxide is left, O2 is no longer produced. When data collection is complete, you will perform a linear fit on the resultant graph to determine catalase activity.

After completing the Preliminary Activity, you will first use reference sources to find out more about catalase, enzymes, and enzyme activity before you choose and investigate a researchable question dealing with catalase activity. Some topics to consider in your reference search are:

  • catalyst
  • enzyme
  • catalase
  • hydrogen peroxide
  • collision theory
  • reaction rate

Educational Standard
International Baccalaureate (IB) 2025
C Interactions and interdependence
Level of organization
1 Molecules
C1.1 Enzymes and metabolism
Standard level and higher level

* The IB Diploma Program is an official program of the International Baccalaureate Organization (IBO) which authorizes schools to offer it. The material available here has been developed independently of the IBO and is not endorsed by it.