Name:________________________________________________Period:___________Date:________________ Do Plant Cells Undergo Both Photosynthesis and Respiration? Background Information: You know that plants undergo photosynthesis, but do they also undergo cellular respiration? In this lab we will use Anacharis, which is an aquatic plant and Bromothymol blue. Bromothymol blue is an indicator for carbon dioxide, which means it indicates the presence or absence of carbon dioxide by changing color. Bromothymol blue is blue in the absence of carbon dioxide, green with small amounts of carbon dioxide and yellow with high amounts of carbon dioxide. Note that the Bromothymol blue has been diluted with water. Materials: test tubes test tube rack straw parafilm to seal test tubes water tape and marking pen Anacharis sprigs scissors flask bromothymol blue tin foil goggles light source dropper Pre-Lab: How does bromothymol blue change color? Original color of Bromothymol blue _________________ Color of Bromothymol blue after blowing into it for 5-10 seconds________________________ Color of Bromothymol blue after blowing into it for 30 seconds or more __________________ Equation for Photosynthesis: __________________________________________________________ _______________is taken into the plant (removed from the environment or BB) during photosynthesis Equation for Cellular Respiration:______________________________________________________ _______________is released by the plant (added to the environment or BB) during cellular respiration Based on the equations, what must be present for photosynthesis to occur? ___________________________ Based on the equations, what must be present for cellular respiration to occur? _________________________ Would the presence or absence of oxygen affect the color of the Bromothymol blue? When you make your predictions, determine if all of the ingredients are present and if so is CO2 being added to the BB or removed from the BB? Ingredients in all the setups – water, dissolved oxygen in the water, and glucose stored in the leaves of the plant. Prediction Table: Setups – All have plant, CO2 absent or BB and water present Original Color of BB Light or Dark 1 Predicted Color of BB after 24 hours Explanation – Why will the BB be that color? What process is happening? Light Absent 2 Dark 3 Light Present 4 Dark Results Table: Color Change of Bromothymol Blue after 24 hours. Setups – All Light or Predicted Original have plant, CO2 absent or Dark Color of BB Color of BB and water present after 24 BB hours 1 Explanation – Why will the BB be that color? What process is happening? Light Absent 2 Dark 3 Light Present 4 Conclusion Questions: Answer using complete Dark sentences on the back of this sheet. 1. What process causes bromothymol blue to turn from blue to green or yellow? Explain what is happening. 2. What process causes bromothymol blue to turn from yellow back to blue? Explain what is happening. 3. There are two setups where it was impossible for photosynthesis to occur. What are the two setups and why was it impossible? 4. Are there any setups where cellular respiration could not occur? Explain. 5. There are two setups where both photosynthesis AND cellular respiration occurred. Which two setups are these and explain how it is possible that both reactions occurred?