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Osmosis Investigation

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Introduction

Osmosis Investigation Aim: The aim of this investigation is to explore osmosis in potato cells and find approximately the concentration of sucrose within potato cells by measuring the change in mass of potato chips when immersed in different sucrose solutions for a set period of time Introduction: Osmosis happens in the cells of all living things. It is a simple process where water molecules diffuse from one cell to another through the partially permeable cell membrane. (the membrane has tiny holes in it that allow simple molecules, such as water, to pass through) During the process of osmosis, water moves between higher and lower concentrated solutions of either saline or a sugar solution until water molecules are evenly distributed between the two (or more) solutions (until they reach equilibrium), and in the case of cells, when the cells are of equal dilution. This movement of water is called diffusion. In the example below, there are two unbalanced solutions separated by a partially permeable membrane. Solution A has a higher concentration of sugar molecules than Solution B. As the process of osmosis begins, the water molecules from solution B begin to move into solution A, seen below. After time, enough water molecules have moved to achieve equilibrium, and the process stops. ...read more.

Middle

1 sharp scalpel ( to cut chips to size) 1 large potato (to take chips from) 6 sugar solutions of varying concentrations; 0%, 10%, 20%, 30%, 40% and 50% (to place potato chips in to find concentration) 1 stop clock that will time 1 hour (to keep amount of time in solution the same for each chip) 1 test tube rack (to hold the test tubes during the experiment) 6 soft tissues of the same make (to remove excess solution from the potato chips before their mass is measured) 6 beakers (for mixing the different solutions in) 6 30ml measuring cylinders ( to measure amount of solution each chip is placed in) 1 pair of tongs (to remove chips from solutions) Method: 1.Prepare a range of sugar solutions of varying concentrations; 0%, 10%, 20%, 30%, 40% and 50% in separate beakers to prevent contamination. 2. Take 6 sections of potato using the 10mm borer, remove skin 3. Carefully cut each section to 50mm in length using the scalpel & ruler 4. Measure mass of each chip with top pan balance to ensure each is almost the same. Any major differences mean the chip must be discarded and a fresh one made. 5. Record your mass readings for future use in a results table. ...read more.

Conclusion

6. Place the test tubes in a test tube rack and carefully measure out 25ml of each solution and pour it into the relevant tube. 7. Place the potato chip in the tube containing the 50% solution. Start a stop clock as the chip enters the tube. 8. Leave the chip for one hour. 9. Carefully remove the chip with tongs, remove any excess moisture with a soft tissue and measure the mass immediately with the top pan balance. Quickly record the result. 10. Place the chip into the test tube containing the 0% solution as quickly as possible to prevent evaporation and start the stop clock. 11. Leave the chip for 1 hour. 12. Carefully remove the chip with the tongs, remove any excess moisture with a soft tissue and measure the mass with the top pan balance. Record the result. 13. Repeat experiment 3 times to check your findings. This preliminary experiment would determine whether or not osmosis is reversible and a full investigation into this matter could then be performed. Other than those things, not much else could be changed, as the results were very reliable due to the extensive precautions taken to make it a fair test. In the future yet more experiments could be performed to learn more about osmosis, such as seeing how time affects osmosis or how surface area exposed to solution affects rate of osmosis. Also, different vegetables could be used to examine variations in sucrose concentration in different species. ...read more.

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