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IA Model Report - Testing the capacity of biological buffer...

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Testing the capacity of biological buffer systems to resist changes in pH P. H. Meter DESIGN Background: Organisms, and therefore their tissues and cells, are constantly working to maintain homeostasis of their internal environments. For example, excess CO 2 in blood, a tissue, as a product of metabolism , reacts with water in the blood to form carbonic acid . The carbonic acid releases hydrogen ions (H + ) into the blood, potentially lowering the pH of the blood and causing a dangerous condition called acidosis . Furthermore, other tissues must maintain pH homeostasis to provide optimum working environments for enzymes, pH sensitive molecules, and products of metabolism may compromise pH homeostasis. Yet, organisms rarely die of acidosis and therefore must have adequate systems in their tissues for buffering against changes in pH (i.e. buffering capacity). The purpose of this study is to investigate the ability of select tissues (cells and extracellular fluid) from a plant and an animal to resist changes in pH. Research Question: Do the tissues of organisms resist changes in pH? Hypothesis: Plant and animal tissues may have the ability to resist changes in pH. Prediction: The initial pH of tissues from plants and animals will not change significantly compared with distilled water, with addition of 0.1 M HCl and 0.1 M NaOH until the buffering system is overwhelmed. Independent Variable: Volume (mL) of HCl or NaOH added Dependent Variable: pH of water or tissue solution Graph of Predicted Results (solid lines are distilled water; dotted lines are animal or plant homogenate) : 1 1 2 3 4 5 6 7 8 9 10 11 12 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Number of Drops
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Controlled Variables: Temperature, concentration of tissue solution, volume of solution tested, water for making each solution. Discussion for how variables listed above will be controlled: Temperature of test solutions will be recorded with a lab thermometer before acid or base are added and at the end of each experimental protocol. The mass of plant or animal material to volume of water ratio will remain constant (100 g tissue: 1,000 mL water). All tests will be done on 25 mL of tissue solution. All tissues will be made with distilled water and distilled water will be used as the control against which the living tissues will be compared. Drawing or Photo of Design, Research Site, Experimental Setup, etc. (when appropriate): Materials: Safety goggles 2, 50-100 mL beakers 0.1 M HCl bottle, with pipette 0.1 M NaOH bottle, with pipette pH paper (pH 1-12 Hydrion) Forceps 25 mL graduated cylinder Water (pH 7) Liver and potato tissue Other plant tissues; Viele Lake water Mortar and pestle Procedure A, Control: 1. Pour 25 mL of distilled water into each of two small beakers (50-100 mL).
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