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Test on osmosis and its effect on pieces of potato

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Introduction

BIOLOGY LAB REPORT 1. ~~Test on osmosis and its effect on pieces of potato~~ *~Aim: to investigate the effect of osmosis on a plant cell (potato chips), left in different concentrations of sucrose solution, and distilled water, for a period of 1 day. *~Theory: Osmosis is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration. Semi-permeable membranes are very thin layers of material (cell membranes are semi-permeable), which allow some things to pass through them but prevent other things from passing through. . A region of high concentration of water is either a very dilute solution of something like sucrose or pure water. In each case there is a lot of water: there is a high potential of water. A region of low concentration of water is a concentrated solution of something like sucrose. In this case there is much less water. When you put a plant cell into liquid containing water one of three things will happen. * If the liquid surrounding the cell has a higher water concentration (hypotonic) than the cell, the cell will gain water by osmosis. Water molecules are free to pass across the cell membrane in both directions, but more water will come into the cell than will leave, as the net movement of molecules is from a higher concentration to a lower concentration. ...read more.

Middle

*~Fair test: In order to make this a fair experiment, few things must be kept in mind: -The beakers should be kept in the same environment and temperature throughout. -The top pan balance should be brought to zero before conducting the weighing. -We should be careful not to perform parallax errors while taking each potato chip's measurement. *~Apparatus: . 1. 4 pieces of raw potato 2. Cork borer- used to extract pieces of potato, 3. 4 beakers 4. Marker 5. Salt solution of 0.1 moles 6. Salt solution of 0.3 moles 7. Salt solution of 0.5 moles 8. Distilled water 9. Top pan balance 10. Ruler Procedure: 1. Using the cork borer, carefully extract 4 pieces of potato from the single raw potato. Apply force on the cork borer, in order to get a fine, cylindrical shape. 2. Pour each of the solutions in different beakers. 3. Label each of the beakers, according to the level of molarity(or distilled water), with the marker. 4. Measure the length of each potato chip, using the ruler, and record the readings. 5. Weigh each of these chips, using the top pan balance, and record the readings. 6. Place each of the chips in the respective beakers, filled with different concentrations of salt solution. ...read more.

Conclusion

E.g. Chip kept in distilled water: increased in length by 6.66% and in weight by 12.6% Error analysis: There wasn't really any scope for errors in the experiment as by far, all precautions were taken to ensure it being a fair test, without any unnecessary safety hazards. - But it is possible that some of the potato could have gotten extremely soggy and broken off into the water, leaving behind the chunk of potato. This would have been difficult to notice; therefore it is not a proved, but possible error. - As everything that would ensure a fair test was taken care of, there weren't any other noticeable or intentional errors. - It is possible that the solution was not accurately concentrated according to the said no. of moles. - The potato could have disintegrated into the water. - The weight of the potatoes weren't very accurate as while weighing it, the breeze etc. could have altered the results. Improvements: As the experiment followed strict guidelines, there wasn't any scope for improvement either. But the implementation of one aspect could have made test easier, and could have shown the results in a more comparative basis. - The potato chips should have been cut in equal lengths, therefore not only making the test easier, but the comparing of the decrease and increase would have been better and the results would have been more impressive, and more comprehensive. ...read more.

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