Photosynthesis and Respiration (CO2 and O2)

Figure from experiment 31C from Biology with Vernier


Plants make sugar, storing the energy of the sun into chemical energy, by the process of photosynthesis. When they require energy, they can tap the stored energy in sugar by a process called cellular respiration.

The process of photosynthesis involves the use of light energy to convert carbon dioxide and water into sugar, oxygen, and other organic compounds. This process is often summarized by the following reaction:

{\text{6 }}{{\text{H}}_{\text{2}}}{\text{O  +  6 C}}{{\text{O}}_{\text{2}}}{\text{  +  light energy}} \to {{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}}{\text{  +  6 }}{{\text{O}}_{\text{2}}}

Cellular respiration refers to the process of converting the chemical energy of organic molecules into a form immediately usable by organisms. Glucose may be oxidized completely if sufficient oxygen is available by the following equation:

{{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}}{\text{  +  6 }}{{\text{O}}_{\text{2}}} \to {\text{6 }}{{\text{H}}_{\text{2}}}{\text{O  +  6 C}}{{\text{O}}_{\text{2}}}{\text{  +  energy}}

All organisms, including plants and animals, oxidize glucose for energy. Often, this energy is used to convert ADP and phosphate into ATP.


In this experiment, you will

  • Use an O2 Gas Sensor to measure the amount of oxygen gas consumed or produced by a plant during respiration and photosynthesis.
  • 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.

Sensors and Equipment

This experiment requires each of the following Vernier sensors and equipment (unless otherwise noted):

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

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  • Step-by-step instructions for computer-based data collection
  • List of materials and equipment

Note: The experiment preview of the computer edition does not include essential teacher information, safety tips, or sample data. Instructions for Logger Pro and other software (such as LabQuest App or TI handheld software, where available) are on the CD that accompanies the book. We strongly recommend that you purchase the book before performing experiments.

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Standards Correlations

No standards correlations for this experiment.

Experiment 31C from Biology with Vernier Lab Book

<em>Biology with Vernier</em> book cover

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