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Biology Coursework - Osmosis

Extracts from this document...

Introduction

Contents Pg. 3 - Plan: Introduction & Aims Pg. 4 - Plan: Osmosis Research Pg. 6 - Plan: Potato Cell Research Pg. 8 - Plan: Variables & Non-Variables Pg. 9 - Plan: Proposed Method Pg. 10 - Plan: Hypothesis Pg. 11 - Preliminary: Introduction and Aim Pg. 12 - Preliminary: Variable and Controlled Variables Pg. 13 - Preliminary: Method Pg. 15 - Preliminary: Results Pg. 17 - Preliminary: Graphs Pg. 18 - Preliminary: Conclusion & Evaluation Pg. 19 - Experiment: Equipment Pg. 20 - Experiment: Safety Pg. 21 - Experiment: Method Pg. 22 - Results: Table Plan: Introduction & Aims In this coursework, I will be studying the process of Osmosis. To do so I will carry out an experiment, this will look at the effects of Osmosis on chips of potato in a sucrose solution. The experiment will involve placing identical potato chips into different sucrose solutions with varying concentrations, after 45 minutes, I will take the potato chips out of the solutions and weigh them, changes in mass would indicate Osmotic activity. My aim is as follows: "To investigate the effect of varying concentrations of sucrose solution on the amount of osmotic activity between the solution and a potato chips, identical in size" I hope that by the end of the investigation, I will have a better understanding of osmosis and a conclusion that demonstrates that knowledge. Plan: Osmosis Research To help me plan my investigation better, I have decided to do some background research on Osmosis, this is what I found: Osmosis is simply a special type of diffusion; the movement of water molecules from a high water concentration (low solute concentration, said to be high water potential), to a lower water concentration (high solute concentration, said to be low water potential) through a partially permeable membrane. This diagram shows the process of osmosis: "During osmosis, more water particles pass from the pure water into the dilute solution than pass back the other way. ...read more.

Middle

Duration of Experiment To make sure none of the potato chips are in the solution longer than the rest, I will use a stop watch to time the experiment, and leave each potato chip in the solution for exactly 30minutes. Weighing Scales To prevent variation in results from different weighing scales, I will weigh each of the potato chips on the same set of scales, blotting each chip first, to ensure no surface water Preliminary: Method This is the method I used for my preliminary test: Apparatus: * 4 Boiling Tubes * Test Tube Rack * Distilled Water * 1.5M Sucrose Solution * Potato Borer * Potato * Scalpel * Ceramic Cutting Tile * Scales * Measuring Cylinder * Paper Towel * Stop Watch Method: 1. Place all three boiling tubes into test tube rack, using the measuring cylinder measure out 20 ml of distilled water and place 20 ml each in two boiling tubes. Also measure 20ml of a 1.5 molar concentration of sucrose solution and place it into two of the test tubes 2. Using the potato borer and the scalpel, on the ceramic cutting tile, cut the potato into four chips, the first two 2cm long and the second two 3cm long. Weigh each chip and note down the starting mass, before placing 1 chip in each of the solutions. 3. Time 30 minutes on the stopwatch. 4. After 30 minutes, begin to remove the potato, hold each chip above the boiling tube for a few seconds to allow as much surface water as possible to drip back into the tube. 5. Blot each potato chip with a paper towel to remove any remaining surface water before weighing the chips on some scales and noting down the results. 6. Repeat the tests one more time then use the results to draw graphs and conclusions. Preliminary: Results 1st Test - Distilled Water --- 2cm 3cm Mass (g) ...read more.

Conclusion

In the future, I might consider planning more in advance for the experiments, to allow more time to rearrange extra-curricular activities, however, in the end I got the results I needed and whilst the problem was not resolved, it was worked around. Conclusion: Further Experiments In the future, I would be interested in investigating further into the equilibrium between the potato and the sucrose solution. Since I already know that the equilibrium must be around 0.5M, I would conduct an experiment to study closer the molar concentrations around this around this area. This would be my proposed method: 1. Place 11 boiling tubes into a test tube rack, using the measuring cylinder measure out 20ml of each concentration between 0.4 Moles and 0.5 Moles (0.4M, 0.41M, 0.42M, 0.43M, 0.44M, 0.45M, 0.46M, 0.47M 0.48M, 0.49M, 0.5M) and pour them into each boiling tube. Label the test tubes respectively. 2. Using, the potato borer and the scalpel, on the ceramic cutting tile, cut the potato into seven chips, all exactly 3cm long. Weigh each chip and note down the starting mass, before placing 1 chip in each of the solutions. 3. Time 60 minutes on the stopwatch. 4. After 60 minutes, begin to remove the potato, hold each chip above the boiling tube for a few seconds to allow as much surface water as possible to drip back into the tube. 5. Blot each potato chip with a paper towel to remove any remaining surface water before weighing the chips on some scales and noting down the results. According to my graph, the equilibrium would probably fall within the range I have planned to test, so therefore, we would find the exact point at which the potato and sucrose solution have exactly the same water concentration. This extension would hopefully expand my experiment, into a more interesting part of osmosis. ?? ?? ?? ?? Osmosis Coursework Claire Capp 10YSS - 1 - Candidate No. 7037 ...read more.

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This is a detailed and full write up of a well planned and conducted investigation. A high level of scientific knowledge and understanding is evident.

Marked by teacher Adam Roberts 26/04/2013

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