Ap Biology Photosynthetic Organism Free Response

The rate of photosynthesis may vary with changes that occur in environmental temperature, wavelength of light, and light intensity. Using a photosynthetic organism of your choice, choose only ONE of the three variables (temperature, wavelength of light, or light intensity) and for this variable.
• Design a scientific experiment to determine the effect of the variable on the rate of photosynthesis for the organism
• Explain how you would measure the rate of photosynthesis in your experiment
• Describe the results you would expect. Explain why you would expect these results. The rate of photosynthesis is affected by environmental factors like light intensity, light wavelength, and temperature. This experiment will test the effect of light intensity on the rate of photosynthesis in a plant called Elodea. Elodea is an easy plant to use for this experiment because it is cheap, abundant, and easy to take care of. This photosynthetic organism needs to be kept in an aerated freshwater tank. To do this experiment, put the Elodea in a beaker of freshwater. Anchor the Elodea using a small weight like a paperclip so that the plant remains in the same position and up right through the entire experiment. Place the beaker of water containing the Elodea in front of a light bulb. In between the beaker and the light bulb, there should be a separate beaker of water that is used to absorb any heat produced by the light. This way the experiment will not be affected by another environmental factor, temperature. Every thirty seconds for five minutes, count the number of bubbles given off by the Elodea. After the first five minutes, move the beaker containing the Elodea about ten centimeters back and let it stand for two minutes so that it can adjust to the new intensity of the light. Count the bubbles released every thirty seconds for five minutes. Move the Elodea back ten more centimeters, let it adjust for two more minutes, then count the number of bubbles