Investigating Factors Affecting Photosynthesis

Investigating Factors Affecting PhotosynthesisBiologyHS/ScienceUnit: 05 Lesson: 01Objective: Design an investigation to test how one factor may affect the rate of photosynthesis.Background: Recall that photosynthesis is the cellular process in which autotrophs capture lightenergy and convert it to chemical energy (glucose) using carbon dioxide and water. Photosynthesisrequires water, carbon dioxide, and light energy. The products of photosynthesis are oxygen andglucose. One way to determine if photosynthesis has taken place is to measure the pH of a solutioncontaining a water plant. If the CO 2 level in a solution decreases, the pH of the solution will increase.Another way to determine the rate of photosynthesis is to observe and count bubbles of oxygen beingreleased from the plant.Experimental Design:You will be using the materials provided to test one factor that may affect photosynthesis. You willonly need to use some of the materials listed, based on the factor you choose to test.Your experimental design will be written to answer the following question: How does __________affect the rate of photosynthesis?Possible factors to test include: amount/intensity of light, color of light, temperature and/or amount ofcarbon dioxide available.Prediction:When you have selected the factor you will test, write a prediction in your science notebook abouthow this factor will affect the rate of photosynthesis.You will have access to the materials listed below:test tubestest tube rackElodea sprigssodium bicarbonatesolutions (0.5%, 1%,1.5%, 2%)calculatorslight sources (variouswattage bulbs, lamps,sunlight)pH probe andsoftwarecolored cellophanewarm water bathtemperature probe orthermometerruler (metric)safety gogglesaprons©2012, TESCCC 08/23/12 page 1 of 2

BiologyHS/ScienceUnit: 05 Lesson: 01Write your experimental design in your science notebooks. Include a diagram showing the setup ofyour experiment, describing how and what you will measure during your experiment. Your teachermust approve your experimental design before you can conduct your experiment. When yourexperimental design is approved, set up your experiment and collect your data.Test Tube Setup:The standard setup for a test tube (the control) for this experiment is as follows:1. Fill a test tube about ¾ full with 1% sodium bicarbonate solution (baking soda solution).2. Remove the leaves around the very bottom of one sprig of Elodea. Crush the stem end, thenplace the Elodea into the test tube, as demonstrated by your instructor.3. Place a stopper in the test tube.Data Collection:Determine the best equipment and procedure to collect your data. Design and label a data table inyour science notebooks to record your data. Use your data to create an appropriate graph to helpexplain the results of your experiment.Results/Analysis:In your science notebook, explain the results of your experiment and what you learned about how thefactor you chose affects the rate of photosynthesis.©2012, TESCCC 08/23/12 page 2 of 2