Topic 4 Lab report PDF

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Lab report based off of Comparative Cell Membranes and Transport lab...

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Topic 4 Lab: Comparative Cell Membranes and Transport Biology 101 10/23/2020

Exercise 1: D. Was the hypothesis you recorded in Data Table 1 supported or refuted by your experimental results? Discuss your results in relation to your hypothesis. (It is acceptable if your hypothesis was refuted, as long as you can explain WHY.) My hypothesis was incorrect. I was thinking the higher the sucrose level would mean the higher the mass; but it was the opposite. The reason it was the higher the sucrose level the lower the mass is because water leaves the cell through osmosis to meet the equilibrium. E. If you were asked to place potato strips in a solution that would cause the potato to neither gain or lose mass, what molarity would you choose and why? Would this solution be hypotonic, hypertonic, or isotonic? If I was asked to place potato strips into a solution that would cause the potato to neither gain nor lose mass, I would use an isotonic solution with 0.6M sucrose. I assume this solution allows the potato to be isotonic due to the water to sugar ratio being similar to the potato.

Exercise 2: C. In the first part of Exercise 2, a glucose/starch solution was placed in dialysis tubing. Then, the tubing was placed in a cup containing IKI indicator. Did starch stay within the tubing or move out of the tubing? Did IKI indicator stay in the solution in the cup or move into the tubing? Support your answer with the observations you recorded in Data Table 3. The starch stayed in the tubing. The IKI indicator moved into the tubing which turned the starch/glucose mix a dark blue color.

D. In the second part of Exercise 2, the IKI solution in the cup and the contents of the dialysis tubing were heated with Benedict’s reagent. Did sugar stay within the dialysis tubing or move out of the tubing? Support your answer with the observations you recorded in Data Table 4. The sugar stayed in the tubing. The IKI solution did not change in color. Also, when the test tube was heated in the water bath it showed the presence of starch because of the orangish red color.

H. From your data, might it be inferred that a) starch and glucose molecules are the same size, b) starch molecules are larger than glucose molecules, or c) starch molecules are smaller than glucose molecules. Use your data to explain your answer I would infer that answer B is correct. From what I saw, the starch molecules are larger than glucose molecules due to the amount of sugar that is found in starch. Unlike the starch molecules, the glucose molecules were unable to leave the tubing. This is supported by the change of color in the tubing during the starch test. Why does temperature affect the rate of diffusion? (Hint: Consider the relationship between temperature and the speed at which particles move.) From what I observed cold water tended to diffuse the potassium at the fastest rate but then would also settle to the bottom the fastest. The warm water diffused at the slowest rate and would result in a dark bottom color that would be light at the top of the solution. The Ambient water was the fastest to diffuse and went from top to bottom and would pretty evenly distribute the dye.

References: Hands-On Labs, Inc. “Mitosis and Meiosis Lab” www.HOLscience.com...