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DIFFUSION & OSMOSIS How do substances move into and out of cells? Hypothesis: Glucose will diffuse through the dialysis tube (the selective membrane) whereas starch wont.

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Introduction

Diffusion & Osmosis Lab Purpose: How do substances move into and out of cells? Hypothesis: Glucose will diffuse through the dialysis tube (the selective membrane) whereas starch won't. Materials: - Dialysis tubing (20cm long) - Test tubes - 250mL beaker - 500mL beaker - String - Hot water bath - Iodine (KI) solution - Distilled water - 500mL beaker - Benedict's solution - 40% glucose solution - 1% starch solution - Dropper - Syringes Procedure: Preliminary tests: 1. Place 2mL of starch solution in test tube and add one drop of iodine to the solution. Record the result. 2. Place 5mL of glucose solution in a test tube and add 10 drops of Benedict's solution. Place the test tube in boiling water for 3 minutes and record the result. - Iodine tests for starch - Benedicts test for glucose Laboratory tests: 1. Take a piece of dialysis tubing and soak it in distilled water. 2. ...read more.

Middle

There was a color change from yellow to purple when placed a drop of iodine into the starch solution. 2. What happened to the sugar solution and Benedict's when heated? The color changes from blue to orange when we heated the sugar solution and Benedict's. 3. What happened during the experiment while the dialysis tubing was placed in water? While the dialysis tubing was placed in water, glucose diffused out of the dialysis tubing and water went in by osmosis. 4. What happened to the fluid in the beaker that contained the dialysis tubing after it was heated with the Benedict's solution? The fluid in the beaker that contained the dialysis tubing turned from blue to orange after it was heated with the Benedict's solution 5. A membrane that allows some molecules to pass but not the others is called? The membrane that allows some molecules to pass but not the others is called a semi permeable membrane. 6. Can material pass through a membrane in both directions at the same time? Support your statement. Yes. ...read more.

Conclusion

How would this cell respond if placed in a beaker of distilled water? The distilled water will go into the cell until the solute concentrations are equal. As the cell gains too much water, it would burst and die. (animal cell would die but not plant) 6. For the most part, plants, and animals live in either a salt water environment or a fresh water environment, not both. Explain the reason for this using the principles of diffusion. Most plants and animals can't live in both salt water environment and fresh water environment because animals or plants that live in salt water is used to the environment that has more salt and less water. When they are placed in fresh water, its environment become hypotonic to the cell. This would result in water entering the cell causing it to lyse. As for animals or plants that live in freshwater, they are used to an environment with more water and less salt. When they are placed in salt water, its environment become hypertonic to the cell resulting water leaving the cell. Once the water leaves the cell, it becomes plasmolyzed. ...read more.

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