1. Photosynthesis Color and Wavelengths Live, Love, Leaf: Emmie, Grace, and Marissa

2. Research Question: How do different colors of light affect the rate of photosynthesis?

3. Hypothesis: Warm colors, such as red and orange, will cause a faster rate of photosynthesis than cool colors, like blue or purple; however, each rate will be less than that of the regular light. This is because plants receive their energy from the sun, so natural light will produce a higher efficiency of photosynthesis. Since warm colors provide more heat, much like the sun, the plants will thrive better under that lighting and thus, the rate will be faster than cool colors.

4. Experimental Control Regular light was the control group in this experiment. Leaf disk floatation was conducted first under regular light so that the results could later be compared when the light was covered by different colored cellophane for the other cups.

5. Procedure 1. Gather materials. 2. Label six cups with sharpie marker as A, B, C, D, E and F. 3. Add a pinch of baking soda to cups A, B and C. 4. Add water about 6 cm deep to cups A, B and C. 5. Stir to dissolve thoroughly. 6. Add a drop of liquid soap to the solutions and stir thoroughly, do not make suds. 7. Divide the solutions into two cups, making a total of 6 cups. 3 cm from cup A should go to cup d, 3 cm of cup B should go to cup E, and 3 cm of cup C should go to cup F. 8. Use the hole puncher to create a total of 54 spinach leaf disks. Each cup will end up having 9 disks each. 9. Once all of the leaf disks have been punched out, remove the plunger from the syringe 10. Pour 9 leaf disks into the barrel of the syringe, making sure that they all move towards the narrow end where a needle would normally be. 11. Carefully push the plunger back into the syringe, avoid damaging the leaf disks. 12. Place the syringe tip into the bicarbonate + soap solution and pull up some of the solution until the syringe is about ⅓ full.

6. Procedure Cont’d 13. Holding the syringe with the tip upwards, cover the open tip with your finger. Pull back on the plunger a bit with your finger over the open tip. 14. Hold the “vacuum” for about 10 seconds and then gently release. 15. Pull the vacuum 3 more time, or until all of the disks sink in the solution. Add more soap if this has to repeated more than 5 times. 16. Pour the infiltrated leaf disks into cup A. 17. Place cup A under the regular white light, 3 cm away 18. At one minute intervals, count the number of leaf disks floating and record the number. Do this for 20 minutes. 19. Repeat steps 10-18 a total of 5 more times. The first time, substitute cup B for cup A and cover the light with red cellophane. Attach cellophane with tape, making sure no regular light can get through 20. For the second time, substitute cup C for cup A and cover the light with green cellophane. 21. For the third time, substitute cup D for cup A and cover the light with blue cellophane. 22. For the fourth time, substitute cup E for cup A and cover the light with orange cellophane. 23. For the final (fifth) time, substitute cup F for cup A and cover the light with purple cellophane.

7. Data: Amount of Leaves Floating Under Different Colored Lights MinutesRegular Light Red Light Green Light Blue Light Orange Light Purple Light 0 0 Leaves 1 2 3 3 Leaves 0 Leaves 4 1 Leaf0 Leaves 4 Leaves 0 Leaves 5 1 Leaf0 Leaves 7 Leaves 0 Leaves 6 3 Leaves 0 Leaves 8 Leaves 0 Leaves 7 4 Leaves 0 Leaves 9 Leaves 0 Leaves 8 6 Leaves 0 Leaves 9 Leaves 2 Leaves 0 Leaves Caption: ❖ At seven minutes, the only color with all 9 leaves floating was blue. ❖ Green and purple didn’t have any leaves floating throughout the experiment. ❖ By eight minutes, regular light had 6 leaves, red had zero, and orange had two.

8. Data Continued: Amount of Leaves Floating Under Different Colored Lights 9 7 Leaves0 Leaves 9 Leaves3 Leaves0 Leaves 10 9 Leaves1 Leaf0 Leaves9 Leaves3 Leaves0 Leaves 11 9 Leaves1 Leaf0 Leaves9 Leaves3 Leaves0 Leaves 12 9 Leaves1 Leaf0 Leaves9 Leaves4 Leaves0 Leaves 13 9 Leaves2 Leaves0 Leaves9 Leaves5 Leaves0 Leaves 14 9 Leaves2 Leaves0 Leaves9 Leaves6 Leaves0 Leaves 15 9 Leaves2 Leaves0 Leaves9 Leaves7 Leaves0 Leaves 16 9 Leaves2 Leaves0 Leaves9 Leaves7 Leaves0 Leaves 17 9 Leaves3 Leaves0 Leaves9 Leaves8 Leaves0 Leaves 18 9 Leaves4 Leaves0 Leaves9 Leaves 0 Leaves 19 9 Leaves4 Leaves0 Leaves9 Leaves 0 Leaves 20 9 Leaves4 Leaves0 Leaves9 Leaves 0 Leaves Caption: ❖ By the end of 20 minutes, three colors had all leaf disks floating: regular, blue, and orange lights. ❖ Red light had a total of four disks floating at the end of the experiment

9. Pictures

11. Graph ●The green results are plotted underneath the data for purple because they shared the same results from the experiment.

12. Discussion: Background ● The region of “visible light” on the electromagnetic spectrum corresponds to a wavelength range of 400 to 700 nanometers. The colors in this region range from violet to red. ● Violet light has a wavelength of about 400 nm ● Blue light has a wavelength of about 475 nm ● Green light has a wavelength of about 510 nm ● Orange light has a wavelength of about 590 nm ● Red light has a wavelength of about 650 nm ● White (Regular) Light is composed of the entire spectrum ● Plants have two types of chlorophyll: types a and b. Chlorophyll a is the pigment that is directly involved in photosynthesis. Chlorophyll b acts more indirectly, by transferring the light it absorbs to chlorophyll a. ● There is a 3:1 ratio of chlorophyll a to chlorophyll b in plants; they both absorb similar wavelengths and colors.

13. Discussion of Data ● The two colors that were absorbed best, or the two colors under which all of the leaf discs floated at the fastest speed, were regular white light and blue light. ● The next most efficient color was orange, as nine leaves were floating at the end of the experiment. However, it took a longer time than the regular and blue lights. ● The next best color was red, which only had a total of four leaves floating in it at the end of the 20 minutes. ● Both purple and green had no leaves floating at the end of the experiment, although two leaves under the purple lights were slowly beginning to rise around 20 minutes.

14. Discussion: Analysis, Explanation, and Interpretation of Data ● Since white light is composed of the entire color spectrum, plants generate a lot of energy from it and so it is the best light for plants, explaining why - in photosynthesis - plants receive so much energy from the sun. ● Plants absorb lower wavelengths (colors under green) well. Both types of chlorophyll can absorb blue, with chlorophyll b, absorbing it even better than a. This explains why blue, which has a wavelength of approximately 475 nanometers, produced the best results in the experiment. ● Since lower wavelengths are absorbed better by plants, it is unusual that purple did not have any floating leaves at the conclusion of the experiment. ● Both chlorophylls are also capable of absorbing colors higher on the spectrum such as orange and red. Chlorophyll a is better at absorbing red, while b is better at absorbing orange. Therefore, both of these colors showed success during the experiment. However, because the rate of absorption is not as efficient as that of lower wavelengths, the results for red and orange light showed less productivity.

15. Discussion: Analysis, Explanation, and Interpretation of Data Why were no leaves floating under green light? ● Chlorophyll absorbs the entire visible color spectrum except for green. ● Instead of being absorbed, green light is reflected, which explains why leaves are perceived to be green. ● This is why, in the disc leaf flotation experiment, no leaves floated under green light.

16. Possible Experimental Errors ● Errors could have easily come from the colored cellophane over the regular light. If there was an area where regular light could have gotten through, the results would have been, perhaps, more efficient than they should have been. ● Some of the cellophane sheets were too dark or too thin (light) so this could have changed the strength of the light hitting the plants. The blue, for example, was too thin and so a second sheet had to be applied. Since plants react so well to this wavelength, having a more intense amount of the color could have made the results better. ● Simple human error in the form of set up issues, such as the lamps not being the exact same distance from each cup, or the cups not being directly under the light bulb could have changed how the light hit the plant, and thus how quickly the leaf discs floated

17. Conclusion The original hypothesis was: warm colors, such as red and orange, will cause a faster rate of photosynthesis than cool colors, like blue or purple; however, each rate will be less than that of the regular light. This is because plants receive their energy from the sun, so natural light will produce a higher efficiency of photosynthesis. Since warm colors provide more heat, much like the sun, the plants will thrive better under that lighting and thus, the rate will be faster than cool colors. The data collected in this experiment actually refutes the hypothesis. The more efficient color was blue, which had all nine infiltrated leaf discs floating by 8 minutes into the experiment. The rate of this was slower for warm colors. Under orange light, all nine leaves were floating at 18 minutes, while under the red light only a total of 4 leaf discs floated. The hypothesis was based on knowledge of the efficiency of heat source from the sun in photosynthesis. In actuality, the rate is more affected by the wavelengths of the different colors. With a lower wavelength, cool colors were a more efficient color to place the leaves under than the warm colors.

18. Works Cited http://science-edu.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html http://www.bio.umass.edu/biology/conn.river/chlorophyll.html http://i.stack.imgur.com/VYS0X.png