Lab report photosynthesis

Lab—plant pigment chromatography and photosynthesis Introduction: Background information Photosynthesis is the process that the plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar (National Geographic, 2023). Sunlight, which our eyes perceive as “white” light, is a mixture of different wavelength. Many of these wavelengths are visible to our eyes and make up what is known as the visible spectrum. Pigments are the molecules that the plants use to absorb sunlight. Different pigments have different colors. When the temperature drops in the late of the year, chlorophyll molecules break down first, leaving the reds and oranges of the accessory pigments for all to see. And this is why the leaves look red or orange in the autumn. The plant’s principal pigment is chlorophyll. The two types of chlorophyll found in plants, chlorophyll a and chlorophyll b, absorb light very well in the blue-violet and red regions of the visible spectrum. However, chlorophyll does not absorb light well in the green region of the spectrum. Carotenoids are also accessory pigments involved in the capture of light energy in photosynthesis. There are two types of carotenoids: those that do not contain oxygen are called carotenes, and those that do contain oxygen are called the xanthophylls. Like the chlorophylls, carotenoids are bound to proteins within the plastids. Unlike carotenoids and chlorophylls, anthocyanin, also a kind of pigment, do not participate in photosynthesis and may appear red, purple, or blue. Anthocyanin occurs widely among higher plants and are the pigments that generally give color to flowers, but also occur in leaves and fruit. In leaves, these pigments often help protect against excessive sunlight that can damage some leaf tissues. In the plants, the photosynthesis process often happens in chloroplast. Pigment such as chlorophyll are in the thylakoid which is a saclike photosynthetic membrane inside the chloroplast. The process of chromatography separates the molecules because of the different solubilities of the pigments in one type of leaves. In paper chromatography, paper marked with an unknown, such as plant extract, is placed in a developing chamber with a specified solvent. The solvent carries the dissolved pigments as it moves up the paper. The pigments are carried in a different rate due to the different solubility. According to the formula to calculate Rf, a pigment that is the most soluble will travel the greatest distance and a pigment that is less soluble will move a shorter distance (Plant Travelling Lab, 2010).

(the formula of calculating Rf)

Purpose To separate, isolate, and identify photosynthetic pigments in spinach, Chinese Cabbage, and clover.

Materials and procedures 1 100 mL flask with a cork 1 small/medium test tube with cork and rack 1 plastic pipette 3 mL 1 Scissor 2 Spinach leaves 2 Chinese Cabbage leaves 2 Four Leaves Clovers 1 pencil 2 ml SiO 2 1 Funnel 1 ruler 1 pestle and mortar 3 capillary tubes 3 chromatography paper strips Nylon mesh Chromatography solvent - 4 mL Ethanol -4mL CaCO3-4mL Prediction The pigment which has the greatest solubility will move the fastest distance from the origin point. Procedures

Collect all the materials needed.
First, label your 3 small/medium test tubes: Spinach, Chinese Cabbage, and Four Leaves Clovers
Set the test tubes aside in the test tube rack.
Obtain the spinach leaves. Observe the leaf color and independently record it for your results and lab report.
Cut or tear the spinach leaves into small pieces. Ensure that you remove the thick midrib of the leaves.
Place the spinach leaf pieces into the mortar.
Add 1mL of ethanol, along with 1 mL of SiO2 and 1 mL CaCO3.
Grind up the leaves in the mortar using the pestle. Keep grinding until you get a concentrated pigment and liquid at the bottom of the mortar. Set this aside.
Pour 2ml of the solvent (Ethanol) into the small/medium test tube labeled 'Spinach'.
Carefully lower the chromatography paper strip into the small/medium test tube. Ensure that the solvent is no higher than the pencil mark on your paper strip. In fact, you want to ensure that the solvent is slightly lower than the pencil mark on your chromatography paper strip.
Cover the test tube with the cork and set it in the test tube rack to observe. Allow the solvent to travel up the paper strip. This can take about 1 minute. *Video record this part of the experiment showing the movement of your solvent and separation of colors.
As the solvent rises you will observe the leaf exact that was applied to the paper strip. As the solvent travels upward, it will get separated into its constituent pigments.
Once you notice that the solvent has stop moving for a period (no more colors running), remove the paper strip from the test tube and place it on the desk.
With a pencil mark where the final color stopped.
Once you have marked the point where the color(s) have stop moving, you now need to calculate the distance the colors have travelled from the point of origin (the original pencil line that you first drew on the chromatography paper strip). This is known as the distance travelled or moved by the solvent.
Next, mark the front edge of each pigment for each color, and you want to measure how far each pigment, or each color moved. From the point of origin (the original pencil line that you first drew on the chromatography paper strip). Here is an example below:
Calculate the R value for each pigment that you found on your chromatogram. To do this for each color you want to take the distance moved by the pigment (in mm) and divide this by the distance that the solvent has moved (in mm).
Once you have calculated the R values for each pigment that is observed on your chromatogram you can compare it against known published R values to help identify the pigments on your chromatogram, and therefore the pigments in your leaf. *Example: The published R factor for Carotene tends to be between 0.89-0, so if you obtain a number within this range, and it tends to be a yellow orange color it is likely to be the pigment Carotene. Use the table below to find the published R values.
Record all results in the space provided on the results sheet.
Repeat steps 4-27 this time use with the Chinese Cabbage leaves.
Once completed, repeat steps 4-27 this time use with the Four Leaves Clovers.
Record the results for the three trials.
Clean your area and prepare to be dismissed.

Data collection: 1 the results of each chromatogram on the diagram below (6 pts):

Label the pigments observed for each strip using the following information. Take decent photo of your labeled chromatograph(s) for your lab report. (5 pts)

7/7=0. Chinese Cabbage

1.8/7.3=0 2.2/7=0. 2.4/7= 0. Four Leaves Clover

Analysis of results: Comparing with the data in the table and color in the paper, one can see in the spinach, 3 is the light green which means that it is chlorophyll a. 6 cm is the dull green which means that it is chlorophyll b. And in the 7 is the yellow which means that it is xanthophyll. However, in the table, according to the published Rf factor, in the place of 3 cm, it is chlorophyll b, and in the place of 6, 6, 7cm, it is carotene. Comparing with the data in the table and color in the paper, one can see in the Chinese Cabbage, the 1 cm place is bright green which indicates that it is chlorophyll a. In the 0 cm place is bright green which indicates that it is chlorophyll a. In the 2. cm place is light yellow, which indicates that it is xanthophyll. Corresponding to the color indicating on the paper, according to the published Rf value and the data calculating in the table, one can see in the 1 place, the Rf value is 0, which is in the range of xanthophyll. However, in the place of 2 and 2 cm, the calculating Rf value is in the range of anthocyanin. In the Four Leaves Clovers, in the paper, one can see that in the place of 1 is bright green which indicates that it is chlorophyll a. In the place of 2 cm is yellow which indicates that it is xanthophyll. However, according to data calculating in the table and the published Rf value, it is shown that in the place of 1, the Rf value equals to 0 which is in the published Rf value of anthocyanin.

Conclusion: Different plants present different plant pigments by chromatography. These pigments can be determined by either their unique Rf values or the color showing on the chromatography paper ranging from yellow to green. And the most soluble pigment is carotenoids and the least soluble is Chlorophyll b.

When I extracted the leaves, I did not dry the funnel. As a result, the water inside the funnel may mix with the plants leaves liquid, and thus influence the final results.
The chromatography paper was not one hundred percent vertical in the flask so that there can be some error.
When I was doing the Four Leaves Clovers, I accidentally dropped a little plant liquid on the edge of chromatography paper, which may influence the distance each pigment move.
The oil from our hands may influence the accuracy of the results. As the equipment need to be reused during the whole process, there could be some other plants’ leaves liquid in the equipment even after cleaning, especially in the pestle and mortar.
We broke one flask while doing the experiment because we did not carried the flask which is in the bottom
We did not calculate the Rf value immediately because of the time limit. Thus some of the point was not so clear after drying a little bit.

Before using the funnel, use the tissue paper to dry it to avoid the inaccuracy bringing by the water.
Use the string to make the chromatography paper suspend on the string and thus can promise the vertical position while putting the chromatography into the flask.
Be careful when using the capillary tubes to avoid the accident as mentioned in the error 3.
To avoid the oil from our hands, next time when doing such an experiment, we can put on gloves, or we can mostly use the tweezers.
Next time when doing the experiment with a combination of equipment, we need to put all of them on an aiding equipment like tube stand to avoid the accident like error 5.
Next time we need to manage our time more efficiently. And if the time is enough, we need to finish one and then calculate that one instead of calculating all of them in the end.

Literature citation Photosynthesis. Education. (n.). Retrieved April 2, 2023, from education.nationalgeographic/resource/photosynthesis/. Part I: The adventures of fred fish - texas tech university. (2010). Retrieved April 2, 2023, from depts.ttu/ciser/science-teacher-resources/traveling- lab/curriculum/green-engineering/Fred_Fish D, L., G, G. shekhar, A, P., & A, P. (2018). Green Chemistry: A Study on acid- base indicator property of various flower pigments. International Journal of Research and Development in Pharmacy & Life Sciences, 7(6), 3155–3163. doi/10.21276/ijrdpl.2278-0238.2018.7(6).3155-

In your own words, explain why most plants will not grow well if kept under green light. (4 pts) This is because the plant reflects the green light. Under the green light , the plants do

the chromatography strip is twice length of the one I used, the Rf value will still not change. This is because every pigment has a unique Rf value. As long as the pigment never changes, the Rf value will not change.