Part 3: Photosynthesis 17. Use the permanent marker to label three test tubes as
ID: 72812 • Letter: P
Question
Part 3: Photosynthesis 17. Use the permanent marker to label three test tubes as 1, 2, and 3. Place the tubes in the test tube rack. 18. Add 3 mL water, 1 mL phosphate buffer, and 1 mL DPIP to each of the three test tubes. Figure 6: A heat-sink for test tubes placed in front of a light source. 19. Use the wooden stir stick to swirl the chloroplast solution (Sucrose and smashed spinach) Then, add two drops of the solution to Tubes 2 and 3. 20. Immediately cover Tube 2 with aluminum foil. 21. Place Tube 1 and Tube 3 in a sunny location or under a strong light. If you place the tubes in front of a light, fill a beaker or clear glass with water and position in between the light source and the test tubes as shown in Figure 6. 22. Monitor the test tubes for several hours, and record how long it takes each tube to turn from blue to clear. After the tubes exposed to light turn clear, remove the aluminum foil from Tube 2 and immediately note the color. Record your data I did this, my tubes didn't change color.
Explanation / Answer
DPIP replaces NADP of photosynthesis. DPIP has blue color. It changes it's color from blue to clear after accepting the electrons.
Tube 1 does not have chloroplast. So, blue color will not change. No photosynthesis.
Tube 2 has chloroplast solution, and is placed in dark. Light is necessary for photosynthesis. So, color will not change until and unless the aluminum foil is removed. After removal of aluminum foil, the color should change. (You must have missed some step. Please cross-check once again).
Tube 3 has chloroplast solution and is placed in light. So, color will change gradually as time passes.