Osmosis Investigation

Osmosis Investigation
Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. Diffusion results because of the random movement of particles. The diffusion of water into and out of a selectively permeable membrane is called osmosis. Because of the selectively permeable membrane, nothing but water and other very small particles can be diffused through osmosis. The cell membrane is similar to the membrane mentioned above, so the cell would lose water because of osmosis if it were placed in an environment in which water concentration is greater than that of the cell. A solution is isotonic if the concentration of dissolved substances is the same as the concentration inside the cell. Osmosis does not occur in an isotonic solution. A hypotonic solution is a solution in which the concentration of dissolved substances is lower than the concentration inside the cell. If a cell were put in a hypotonic solution, osmosis will cause water to move through the cell membrane into the cell. A solution is hypertonic if its concentration of dissolved substances is greater than the concentration inside the cell. If a cell were placed in a hypertonic solution, it would lose water.
All particles that pass through the plasma membrane by the process of diffusion do not require energy, so their movement is called passive transport. The transport of materials against a concentration gradient requires energy, so it is called active transport. Aim Our aim was to find out how sugar solution strength affects osmosis, we did this by doing an experiment and then got the results. The results are as expected the 2m solution has made the potato pieces in the jar shrink. The experiment has proven that the stronger the solution is the more it affects the rate of osmosis in a semi-permeable membrane. The aim that we had was proved right and sought out to investigate osmosis in a more detailed way for us to find out more information about it. Preliminary work I have done this experiment in year 9 but it was not right the experiment was taken wrong and I have learned from this and hope to achieve to understand osmosis from this years work. Prediction Osmosis is defined as the diffusion of water across a partially permeable membrane "from the dilute to the concentrated solution. There are more water molecules in a dilute solution than in a concentrated solution so the diffusion gradient favors water passing across the membrane from the dilute to the concentrated solution. A concentrated solution for example sugar solution has a lower concentration of water molecules because the glucose molecules attract some of the water molecules when they dissolve in the water, preventing them from moving freely. Therefore there are more free water molecules in the dilute solution which can move through to the concentrated solution by osmosis. To find out if our prediction was right we did an experiment. [image] The water molecules pass both ways through the membrane but because there are more on one side than the other, there is a steady net movement of water molecules flowing from the weaker solution to the stronger solution by osmosis. The more concentrated sugar solution fills up with water molecules which act in an attempt to dilute it, until there is the concentration on both sides of the membrane. Equipment Apparatus: Sugar solutions : Distilled water ? 0.0M solution 2m Solution. Paper Towels Scalpel Cork Borer 1 large potato cut out each 6 potato chips to an equal circumference using the cork borer and use the scalpel to cut each piece into a 4cm chip and place them into the pure water. Remember to dry the chips first on the paper towel so that It does not affect the rate of osmosis. Method The method in which the experiment was done was that we cut the pieces of the potato with a scalpel then to 25mm then put them in a glass jar with a sugar solution of 0m and then done the same but put the other 3 pieces in a sugar solution of 2m. Remember to put sticky labels on each of the jars so we know which one had which solution in it. We then left the pieces of potatoes for 24 hours and picked them up with tongues and placed on a paper towel, then they were measured. Then the results were recorded on a table. Then the average was worked out by adding up all of the changes and dividing them by 3. Results The results shows us what happened after 24 hours. Strength of Solution Length Before In mm Length After in mm Change in mm Average Change 2m Solution 25 20 -5 -6.3 25 18 -7 25 18 -7 0m Solution 25 24 -1 0 25 26 +1 25 25 0 After my experiment I found that the potato pieces in the jar with 0m had no growth at all. And the 3 potato pieces in the jar with 2m solution had shrunk smaller. This is because the sugar solution in 2m was higher then that in the 0m. We then wanted to expand our knowledge of osmosis, and find out more detail about the effects of what sugar solution strength does on osmosis. Conclusion Osmosis is the diffusion of water molecules through a partially permeable membrane, diffusion moves from a region of high concentration to a region of low concentration to make everything equal. The graph shows what happened after 24 hours and it shows that 2m made the chips shrink it determines that the stronger the solution the more the osmosis occurs. I conclude that through the results I have collected, my prediction was correct. The chips placed in the distilled water gained weight, while the solutions with the higher percentage of sucrose decreased in weight. Obtaining evidence Info from http://www.usd.edu/~bgoodman/Osmos.htm When water diffuses the process is called osmosis. Water moves from a high concentration of water (less salt or sugar dissolved in it) to a low concentration of water (more salt or sugar dissolved in it). This means that water would cross a selectively permeable membrane from a dilute solution (less dissolved in it) to a concentrated solution (more dissolved in it). [image] Water can cross the cell membrane through the lipid bi-layer and with special proteins. If enough water enters the cell by osmosis, the cell can swell enough to burst open and die. This is demonstrated in the picture below. In this picture a red blood cell is put in a glass of distilled water (all water with no salt or sugar in it). Because there is a higher concentration of water outside the cell, water enters the cell by osmosis. In this case too much water enters and the cell swells to the point of bursting open. In the end pieces of cell membrane are left in the water. Pieces of red blood cell membranes are known as red blood cell ghosts. Evaluation I think in this experiment worked well in certain aspects, because our results show a reliable trend, which agrees with my prediction. I have also been able to analyze the evidence. I found that the necessary concentration at which there will be no change to the chip would be between 0M and 2M. In this experiment everything happened as I expected I have gained knowledge of what osmosis is and may go into more detail in the future. The methods used in this experiment worked because they were fair, a fair test is needed to get right results our results were written down after then experiment to show what had happened over night.

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