Chromatography Experiments for Science Fair Projects

Name: Megan
Grade: 2nd Year High School - Home School
Texas, USA
Science Category: Biology - Botany

Conclusion

After testing for pigmentation in my leaf samples using three different chromatography techniques, my hypothesis was proven partially correct. I stated that I believed that both the broadleaf evergreens and deciduous would contain all the pigments. I also stated that chlorophyll would be the most prominent because all the leaves were visibly green.

Because I learned that carotenoids, anthocyanins, and xanthophylls are all accessory pigments that work with chlorophyll to help absorb light from different wavelengths of the light spectrum, I believed it was necessary for each plant to contain all pigments. This is where my hypothesis was proven correct. Every plant sample, but the yucca, was found to have all four pigments. This, of course, came as no surprise since carotenoids, anthocyanins, and xanthophylls are important in a plants ability to absorb light.

My hypothesis went on to question the intensity of the pigments between the deciduous plants and the broadleaf evergreens. I stated that I believed the pigments in the deciduous plants would have a higher intensity that those of the broadleaf evergreens. I believed this because most of the deciduous plants I had chosen as specimens turn colors in the fall.

After analyzing my data, I observed that the pigments in the samples of the broadleaf evergreen showed to be more intense than the pigments in the deciduous plants. This is the opposite of what I hypothesized. I concluded that this was because I tested the deciduous samples during the season in which deciduous plants are losing their leaves and the pigments are breaking down and the plant is no longer producing the chlorophyll for the leaves. I believed that the broadleaf evergreens showed to be more intense in pigments because they are not preparing to lose their leaves and are still producing chlorophyll and their accessory pigments to continue to make food.

Application for my project basically lays the foundation to use this analysis to determine if a plant is stressed. Because the pigments work as accessory pigments which help absorb light, they are very important to the well being of the plant. If a plant lacks the necessary pigments, it can become very stressed and die. A chromatography test can be used to determine if a plant is lacking any pigments.

What I Would Do Differently Next Time

There are several things I would do differently in the future. The method I used to determine the pigmentations in the leaf cells was destructive. In the future, I would like to use a non-destructive pigmentation test and one where I could really identify of amount of pigment in my leaf samples. I have heard of a machine that measures the reflectance of the leaves based on the light spectrum in order to analyze pigments in a leaf. This would give a more accurate account of what kind and what amount of pigmentation is in the leaf cells.

I’d also like to test the pigmentation in deciduous plants during the growing season and throughout the year to see what kind of pattern the pigments have and their intensities. Because chromatography is an interesting way to determine if a plant is distressed, I would like to expand this project further. I would like to use a more accurate chromatography paper. I would like to test throughout the entire year during each season, and I would like to find a less destructive way to test for leaf pigmentation.

Overall, my hypothesis was partially correct. My results backed up my earlier statement that both deciduous and broadleaf evergreen plants would contain all pigments, but failed to back up the statement in which I hypothesized that the pigments in the deciduous plants would be more intense than those in the broadleaf evergreens.

Bibliography

Begnaud, John. Tom Green County Extension Agent-Horticulture. Interviewed by email. San Angelo, Texas. September 19, 2007 and October 22, 2007.

Cincinnati Parks Board. Leaf Chromatography Project. Nature Next Door. Retrieved September 27, 2008.

Coder, Dr. Kim D. Fall Tree Color Pigments, 1997. University of Georgia Cooperative Extension Service Forest Resources Unit. Retrieved February 18, 2008.

Farabee, M.J. Photosynthesis, 2007. Estrella Mountain Community College Online Biology Book. Retrieved January 30, 2008.

Federal United States Forest Service. Overview. Retrieved January 30, 2008.

Helmenstine, Anne. About Chemistry Website. About. October 4, 2005. Retrieved January 18, 2008.

Scherz Nursery. Interviewed staff horticulturist. San Angelo, Texas. February 7, 2008.

Shakhashiri, Bassam. The Chemistry of Autumn Colors. Science is Fun. Retrieved January 18, 2008.

Tanino, Karen. Leaf Coloration. Garden Line. Retrieved September 27,2007.

The American Heritage Science Dictionary Online Houghton Mifflin Company, 2002. Retrieved February 15, 2008.