Aveneu Park, Starling, Australia

In reactions.” Light reactions “need light to produce

In this lab, we observed, “the ability of differing pigments in spinach to absorb and transmit different wavelengths of light” (packet). The results that we acquired were that there were three different pigments in the vegetable that we used. We found a dark green, lighter green and yellow pigment on the chromatography paper provided to us by the teacher. Based on the visible light spectrum, the wavelengths vary from between 500 to 590 nm since there were traces of both yellow and green.Photosynthesis is “the process used by plants, algae, and certain bacteria to harness energy from sunlight into chemical energy” (LiveScience). This oxidation-reduction process was discovered by the English clergyman, and scientist Joseph Priestley began studying photosynthesis in 1771 after having burned a candle in a closed container. He then burned the candle until the air inside of the container could no longer support combustion. The next thing he did was put a sprig of a mint plant in the container and later found that it had produced oxygen a few days later. In 1779, a Dutch physician Jan Ingenhousz continued Priestley’s work and learned that the plant had to be exposed to light to restore the combustible substance. The process of photosynthesis is carried out by two general processes. These are the light reactions and “dark reactions.” Light reactions “need light to produce organic energy molecules (ATP and NADPH). They are initiated by colored pigments, mainly green colored chlorophylls” (school today). Dark reactions “make use of these organic energy molecules (ATP and NADPH). This reaction cycle is also called Calvin Benison Cycle, and it occurs in the stroma. ATP provides the energy while NADPH provides the electrons required to fix the CO2 (carbon dioxide) into carbohydrates” (school today). The technique that we used was called chromatography. What this does is it separates the molecules in pigments based on their relative polarity and solubility. This means that the more hydrophobic pigments will have less of an affinity for the paper. Therefore they will not bind and move with the solvent front. The materials that were used in this experiment were Chromatography solvent and Lugol’s iodine. The first thing we did was grind up spinach leaves to get the liquid pigment out of them. We then put this pigment on the chromatography paper two centimeters above the bottom of the test tube that we placed the paper in. We then poured about one centimeter of chromatography solvent and let it sit for approximately twenty minutes. The results that we found were that the pigments of the spinach leaf had separated. There were three pigments found: dark green, light green and yellow. This result means that the relative polarity of this pigment is the most hydrophobic since it is green-yellow, which means that chlorophyll b is what gives the leaf its pigment.  “Chlorophyll is the green pigment found in plants that allows them to convert sunlight into usable energy through a process called photosynthesis” (SCIENCING). “Chlorophyll b primarily absorbs blue light and is used to complement the absorption spectrum of chlorophyll a by extending the range of light wavelengths a photosynthetic organism can absorb”(SCIENCING).

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