lab 2 ap bio - Dhaval Rana AP biology October 8, 2009...

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Dhaval Rana AP biology October 8, 2009 Abstract : In this lab, we will be conducting an experiment where we will observe the processes of diffusion and osmosis and investigate the effect of solute concentration on water potential on living plant tissues. The experiment will show how molecules in solution are able to move from an area of high concentration to an area of low concentration. This was done in four different parts. In the first part, diffusion was measured through dialysis tubing. By comparing the initial and final color of the bags and beakers we were able to find the presence of glucose in the bag and beaker. In the second part of the lab, osmosis was measured. Osmosis is a special case of diffusion. Osmosis is the diffusion of water through a selectively permeable membrane from a region of higher water potential to a region of lower water potential. In the third part, water potential was measured. By using potato chunks indifferent molar concentration of sucrose in order to determine the water potential of potato cells. In the fourth part of the lab, Plasmolysis was measured. Plasmolysis is the shrinking of the cytoplasm of a plant cell in response to diffusion of water out of the cell and into a hypertonic solution surrounding the cell. A leaf was observed through a microscope. Then sodium was then put on the leaf. And lastly, the leaf was flooded with fresh water. The leaf was compared to its initial look to its final look. Hypothesis for Part 1: If the solute concentration in the bag is superior than the solute concentration in the beaker, then the solute will shift from the bag into the beaker. Hypothesis for Part2: If the sucrose in the solution is inflated, then the average change in mass is superior. Hypothesis for part 3:If the sucrose molarity is dropped, then the water potential is going to be elevated. Hypothesis for Part 4: If you add NaCl to the plant cell, then plasmolysis will take place. Problem: What effects will diffusion, osmosis, and water potential have on the final results of a model membrane system? Introduction Ideas explored in this lab were diffusion, osmosis and the effect of solute concentration on water potential as it relates to living plant tissues. Molecular diffusion, often called simply diffusion, is a net transport of molecules from a region of higher concentration to one of lower concentration by random molecular motion. When the particles are evenly distributed equilibrium is reached. One factor that has a huge impact on diffusion is temperature. As the temperature increases, the motion of the particles increases. As the steepness of concentration gradient increases, the rate of diffusion increases as well. Osmosis is a process in which a fluid passes through a semi permeable membrane,
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This note was uploaded on 10/15/2010 for the course SCIENCE 161 taught by Professor Potenza during the Spring '10 term at Anne Arundel CC.

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lab 2 ap bio - Dhaval Rana AP biology October 8, 2009...

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