Investigating Photosynthesis and Cellular Respiration Objective: To explore the relationship between snails and Elodea in a closed biological system. To form a hypothesis and design an experiment to test a hypothesis. Procedure: 1. Launching the investigation and read the information in the pop-up window (Problem). 2. Click on the items on the materials list to see what they are to be used for. Record the materials in your journal. 3. Formulate a hypothesis to explain how CO2 cycles in aquarium water through snails and Elodea. Record your hypothesis in your journal. 4. As you follow the instructions in the virtual investigation when you are required to record in the lab notebook you should also record in your science journal. Be sure to include the following information: How you will measure the level of CO2 Your independent variable Your controlled variable(s) 5. You will use all 8 test tubes. Record in your Science Journal what you will have in each tube. Note: You cannot have more than 2 snails or 2 Elodea per test tube. 6. Set up your experiment and record in your journal your prediction of the outcome of each test tube. 7. Run the experiment 8. Record your results in your Science Journal. 9. Answer the question on the back in your Science Journal. Analysis and Conclusion Conclude 1. What is the relationship between snails and Elodea? Analyze 2. Why did the color of the BTB change? 3. What was the importance of a control in your experiment? What would you conclude if the color of the solution in the control changed? Infer 4. When you began the experiment, was there CO2 in the water? In the test tubes that contained Elodea, where did the CO2 go? 5. Which gas did the snails release? What observation supports this inference? Apply 6. Based on the results of your experiment, explain why you need to add the Elodea to your snail aquarium. 7. Write the balanced chemical equation for photosynthesis (label reactants and products). 8. Write the balanced chemical equation for cellular respiration (label reactants and products).