Lab Paper-Plant Pigments and Photosynthesis

Lab Paper-Plant Pigments and Photosynthesis - Lab 4: Plant...

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Lab 4: Plant Pigments and Photosynthesis Introduction: Plants do not grow from just absorbing nutrients in the soil, they use the process of photosynthesis. Photosynthesis, in a nutshell, is the process that allows plants to capture the sun’s energy and store it as chemical potential energy in the bonds of carbohydrate molecules. The glucose made by plants is used by plants and animals as a source of energy. To release the energy contained in the bonds of glucose, the glucose must be converted to ATP through a process called cellular respiration. All plants undergo respiration as well as photosynthesis. Respiration also produces waste products including carbon dioxide and water, which are the same substances that served as raw materials for photosynthesis. The process of photosynthesis begins with light-absorbing pigments in plant cells. A pigment molecule is able to absorb the energy from light only within a narrow ranged of wavelengths. In order to absorb as much of the entire bandwidth from sunlight as possible, different pigments, capable of absorbing different wavelengths, act together to optimize energy absorption. These pigments include the green chlorophyll a and chlorophyll b and the cartenoids, which are red, orange, or yellow. When the light is absorbed into one of these pigments, the energy from the light is incorporated into electrons within the atoms that make up the molecule. These excited electrons are unstable and almost immediately re-emit the absorbed energy. The energy is then reabsorbed by electrons of a nearby pigment molecule. The process of energy absorption, followed by energy re-emission, continues, with the energy bouncing from one pigment molecule to another. The process ends when the energy is absorbed by one of two special chlorophyll a molecules, P680 and P700. These two chlorophyll molecules, named with numbers that represent the wavelengths at which they absorb their maximum amounts of light (680-700 nanometers), are different from other chlorophyll molecules because of their association with various nearby pigments. Together with these other pigments, chlorophyll P700 forms a pigment cluster called photosystem I (PSI). Chlorophyll P680 forms photosytem II (PSII). Plants use different types of photosynthetic pigments. Some photosynthetic
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This note was uploaded on 03/03/2010 for the course AP BIO AP BIO taught by Professor Apbioteacher during the Spring '09 term at École Normale Supérieure.

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Lab Paper-Plant Pigments and Photosynthesis - Lab 4: Plant...

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