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Objectives
In this BioLab, you will:

• Observe photosynthesis in an aquatic organism.
• Measure the rate of photosynthesis.
• Observe how various wavelengths of light influence the rate of photosynthesis.
• Use the Internet to collect and compare data from other students.

• 1000-mL beaker
• Three Elodea plants
• String
• Washers

• Colored cellophane, assorted colors
• Lamp with reflector and 150-watt bulb
• 0.25% sodium hydrogen carbonate (baking soda) solution
• Watch with second hand

• Activity Links
• View Student Data

Safety Precautions
Always wear goggles in the lab.

Skill Handbook
Use the Skill Handbook if you need additional help with this lab.

2. Create a data table to record your measurements. Be sure to include a column for each color of light you will investigate and a column for the control experiment.

3. Place the Elodea plants in the beaker, then completely cover the plants with water. Add some of the baking soda solution. The solution provides CO₂ for the aquarium plants. Be sure to use the same amount of water and solution for each trial.

5. Observe and record the number of oxygen bubbles that Elodea generates in five minutes.

6. Repeat steps 4 and 5 with a different color of cellophane and record your observations.

7. Post your data below.

2. Making Inferences
Explain how counting bubbles measures the rate of photosynthesis.

3. Using the Internet
Make a graph of your data and data posted by other students with the rate of photosynthesis per minute plotted against the wavelength of light you tested for both the control and experimental setups. Write a sentence or two explaining the graph.