Biology Lab Report Anas Mosleh Title: Extraction and analysis of pigments from plants Aim: a) To microscopically identify cells from the aquatic plant elodea b) To observe cytoplasmic streaming of chloroplasts c) To identify the location of starch in Coleus leaves d) To create absorption spectrum for pigments from plant leaves Materials Required: a) Microscope, clean slide, glass slip, beaker, petri dish, spectrophotometer b) Elodea leaf, Coleus leaf, ethanol, lugol?s iodine Procedure: Microscopic Identification of chloroplasts from Elodea: Set up the light microscope, and obtain a leaf from Elodea, add a drop of water on the slide with the leaf and observe under microscope. Identification of starch in Coleus Leaves: Obtain a leaf of Coleus, and place the leaf in a beaker of cold tap water. Remove the leaf and place it on a petri dish. Next transfer the same leaf to a beaker of boiling water. Then transfer the same leaf to a beaker of hot ethanol for 3 minutes in the hot water bath. Remove the leaf; place it on a petri dish and pipet 2mls of lugols iodine over the leaf. Determination of Absorption spectrum: Warm the spectrophotometer for 10-15 minutes and set the wavelength to 400nm. Blank the spectrophotometer using a cuvette of 4mls ethanol. Transfer 4mls of your pigment extract to different cuvette, record the absorbance and remove the cuvette. Change the wavelength to 425nm and repeat the same process until you reach 700nm. Results: Observations of Coleus leaf after various treatments Absorbance?s for leaf extract Conclusion: For this experiment we were to observe a type of leaf under the microscope, and the various changes that happened after each situation. Discussion: In this experiment we observed the complexity of a certain type of leaf called Elodea under the microscope, adding a drop of water over the leaf and observing it under the microscope. The next thing we did is take a Coleus leaf and see various changes that happen to the leaf after placing it in 5 different situations. Firstly, was seeing without treatment. Secondly placing the leaf in cold tap water letting the pink color fade. Thirdly, placing the leaf in boiling water letting it turn to white. Fourthly, taking the leaf into hot ethanol letting it curl up, die, and become crunchy. Fifth, placing lugols iodine on the leaf making it turn black and green. Application: Leaf before treatment Light green with shades of a purple pink in between. Fresh leaf Leaf after cold water Absorbs water, pink color fading Leaf boiling water Purple-pink is gone, turned to white Leaf after hot ethanol Turned white, curled up, dead and crunchy Leaf after Lugol?s Iodine Turned black at the lighter parts, remained green at other. Wavelength Absorbance 400nm 1.005 425nm 1.296 450nm 1.323 475nm 1.012 500nm 0.203 525nm 0.091 550nm 0.107 575nm 0.169 600nm 0.244 625nm 0.312 650nm 0.603 675nm 0.637 700nm 0.024
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