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C4.2.7—Use of light as the external energy source in photoautotrophs and oxidation reactions as the energy source in chemoautotrophs


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

Investigating Primary Productivity

Experiment #17 from Investigating Biology through Inquiry

In this Preliminary Activity, you will gain experience using a Dissolved Oxygen Probe as you measure the DO level of a water sample provided by your teacher. You will also learn how to calculate respiration rate, gross productivity, and net productivity using the light and dark bottle method.

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

  • primary productivity
  • dissolved oxygen
  • net productivity
  • gross productivity
  • photosynthesis
  • cellular respiration
  • respiration rate
  • eutrophication

Photosynthesis and Respiration (CO2)

Experiment #31B from Biology with Vernier

In this experiment, you will

  • Use a CO2 Gas Sensor to measure the amount of carbon dioxide consumed or produced by a plant during respiration and photosynthesis.
  • Determine the rate of respiration and photosynthesis of a plant.

Educational Standard
International Baccalaureate (IB) 2025
C Interactions and interdependence
Level of organization
4 Ecosystems
C4.2 Transfers of energy and matter
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.