Diffusion and Osmosis

Diffusion and Osmosis - Title AP Biology Lab#1 Diffusion...

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Title: AP Biology Lab #1: Diffusion and Osmosis Purpose: In this lab, we will be conducting an experiment where we will observe the acts of passive transport: diffusion and osmosis. The experiment will show how molecules in a solution are able to move from an area of high concentration to an area of low concentration. With this, it will also show us how hypertonic and hypotonic solutions exist, as well as how cells try to get back into an isotonic state. In doing so, this lab will allow us to learn why and how diffusion and osmosis happens in all living things. We will be testing the movement of solutes from their area of high concentration to the area of lower concentration that surrounds them. Hypothesis: Exercise A) I believe molecules of starch and glucose will enter the water in the beaker. Exercise B) I believe osmosis will occur and try to make each solution isotonic. Exercise C) I believe the water potential of the potato will be negative. Exercise D) I believe there is no hypothesis to give. Exercise E) I believe the salt will cause the cell to become hypertonic. Procedure: Exercise A) 1) Obtain a dialysis tubing that has been submerged in water. Tie off an end to form a bag. 2) Test the solution for a presence of glucose. 3) Place a starch solution into the bag. 4) Fill a beaker 2/3 full of water and add a solution to the water. Record the color change of the solution and amount of glucose present. 5) Immerse the bag into the beaker of solution. 6) Wait 30 minutes or until a distinct color change has taken place in both the bag and solution. 7) Test the liquid remaining in the beaker for any presence of glucose. Exercise B) 1) Obtain 6 strips of presoaked dialysis tubing. 2) Tie a knot in one end of each piece of tubing to form 6 bags. Fill them each up with different solutions. 3) Rinse and record weight of each bag. 4) Place each bag into a beaker to find the molarity of the solution in the dialysis bags. 5) Now fill each beaker with 2/3 of water or enough to completely submerge the bag. 6) After 30 minutes, remove bags from water and determine their mass. Exercise C) 1) Slice a potato into 4 discs without skin. 2) Pour assigned solution into a beaker. 3) Measure and record the mass of the 4 discs. 4) Put all 4 discs into the designated solution and let sit overnight. 5) Remove discs. Measure and record their total mass. 6) Calculate percentage change from initial to final and graph data.
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Exercise D) 1) Complete the questions on the calculations of water potential from experiment. Exercise E) 1) Prepare a wet mount slide of an epidermis of an onion. Observe and record what you see. 2) Add a few drops of a salt solution across the slide. Sketch and describe the onion cell.
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Diffusion and Osmosis - Title AP Biology Lab#1 Diffusion...

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