Lab Report-Photosynthesis Essay Example

Lab Report Lab Report-Photosynthesis Paper Lab Report-Photosynthesis Paper Essay Topic: Synthesis When reduced this indicator changes from blue to a colorless solution. When light is absorbed, water is oxidized and the excited electrons are transferred for the process of reducing NADIA+ to NADIA. This transfer is done via the electron transport chain. DUCKPIN is able to capture the electrons that are transferred through the electron transport chain which will cause the color intensity of the indicator solution to decrease. The decrease in intensity of the indicator correlates to an increased rate of photosynthetic activity. Varied light intensities can alter the photosynthetic capability of chloroplasts. As light intensity increases, it is apparent that the rate of photosynthesis begins to decrease until a certain level of light saturation. If the intensity extends over a certain tolerance level, photo inhibition occurs. The light used for photosynthesis requires a specific wavelength for the pigments in chloroplast to absorb it. Light independent reactions occur in the stoma of the chloroplast whereas the light reactions occur in chloroplasts that sit on the ethylated membrane. White light is comprised of all the colors in the spectrum where each of these colors contains different energy; hence they are all of different wavelengths. Since pigments only absorb certain wavelengths within the visible spectrum, the others are transmitted or reflected. Blue and red light tend to contribute to the highest rates of photosynthesis whereas green and yellow result in the lowest rates. The purpose of the experiment was to investigate photosynthetic electron transport, using isolated chloroplast from silver beet leaves. Seven spectrophotometer tubes were numbered and solutions A-D were added according to the volumes in TABLE 1. Tube 1 was capped and inverted several times. The Spectrophotometer was calibrated using tube 1, which contained chloroplasts and sucrose only, as the blank, to ensure that any changes in absorbency for the other treatments could be attributed to the reduction of the dye DUCKPIN. At time, zero (miss), absorbency was recorded for al treatments immediately after addition of DUCKPIN and mixing of contents. This gives a rate per foot-candle and allows you to compare he effectiveness of the light based on color alone. In tube 2, there is a decrease in the absorption rate when the reaction mix is mixed. In test tube 3, the readings of the absorption rate decreases when in the presence of light. There is a decrease in reading up till the 60th minute and then the absorbency rate decreases in test tube 4. In test tube 5, there is a decrease in absorption rate when ADDICT is mixed. The readings for the absorption rate increases up till the 30th minute then it would decrease in test tube 6. In test tube 7, the readings increase up till the 30th minute then it would decrease and increase again. Graph of absorbency against time taken for DUCKPIN dye to turn colorless DISCUSSION The readings obtained in test tube 2 and 4 the readings are good as there is a decrease in absorption as the mixture is placed in the dark. Chlorophyll pigments can only carry out photosynthesis in the presence of sunlight. The dark chloroplasts and boiled chloroplasts showed some signs of photosynthesis but insubstantial compared to the fully functioning chloroplasts. Because DIP measures only the light reactions (because those are the only stages in which NADIA+ is reduced) and DIP reduction was very low in both, we can conclude hat the light-dependent reactions do not occur in either dark or boiled chloroplasts. Boiling most likely damaged (denatured) the chlorophyll beyond repair, so it functions just like as if it was covered with foil occasionally some stray photons will excite the chlorophyll, but holistically, that is not much at all. In test tube 3, the readings of the absorption rate decreases when in the presence of light. In test tube 5 the Hill Reaction will be analyzed by measuring the light absorbency of DUCKPIN as chlorophyll and the electron transport chain reduce it under exposure to light. An electron transfer inhibitor, 3-(3,4-decontrolling)-1,1 methyl-urea (DDCD), which prevents platitudinous from receiving electrons from the primary electron acceptor, will be present in different concentrations to demonstrate the reduction of DUCKPIN as being a consequence of the splitting of H2O and the transfer of electrons from chlorophyll to the primary acceptor and subsequent molecules of the electron transport chain. The rate that the DUCKPIN dye transforms from blue to clear is a function of how frequently electrons are passed through photosynthesis II, measurements of the absorbency of the DUCKPIN dye over exposure time to light will indicate the relative rate of H2O splitting ND photosynthesis II activity under the different concentrations of the DDCD electron inhibitor: the decrease in the rate of absorbency. In tube 6 the readings are such as photons are absorbed by the photometers when there is higher light intensity. A higher rate of photon absorption indicates that more electrons are excited in the photometers which leads to a higher rate of photosynthesis. However the readings are not accurate as the reading fluctuates increasing and decreasing when it is supposed to increase steadily this may be due to errors that was done during the experiment, when the absorbency rate was measured after the 60th minute the test tube was not closed this may have caused the reading to drop. In test tube 7 has high absorbency reading at the end of the 90th minute because green light wavelength is the least effective for photosynthesis. However the reading decreases at the 60th minute and this may be due to the way the test tubes were placed in the ice, the position of the test tube was altered and maybe only half of the mixture was immersed in ice. This may have caused the difference in the reading as the readings were affected by heat and chloroplast is heat sensitive.