Osmosis Experiment with Swede - Essay Example

Osmosis Experiment with Swede In this experiment, I tried to find out the effect of osmosis on slices of swede, a root vegetable, immersed in a pan of water solution. Osmosis is a process where water passes in or out through the tissue of the plant or vegetable. This process explains how plants or vegetables absorb water into its cells or release water from its cells. How does osmosis take place A plant or vegetable is full of cells that contain water. Each of these tiny cells is surrounded by a membrane like our skin. The membrane protects the cell by keeping its parts inside and keeping other things outside. This membrane can stop many things from entering the cell, but it cannot keep water out. Water can pass through the membrane, either going inside the cell or going outside of it. In what direction does the water flow This is what this osmosis experiment will try to find out. According to the scientific theory, water will flow from a place where the concentration of chemicals is lower to another place where the concentration of chemicals is higher. What this means is that if the amount of chemicals inside the cell is higher than the amount of chemicals outside the cell, water will flow from the outside to the inside. The cell will absorb water. When the cell absorbs water, the cell will increase in weight or gain weight because there will be more water inside it. If the amount of chemicals outside the cell is higher than the amount of chemicals inside the cell, water will flow from the inside to the outside. The cell will lose water. When this happens, the cell will lose weight because there will be less water inside it. My experiment therefore will test whether the following hypothesis is true: that water will pass through the cell membrane of a plant or vegetable from the solution where the amount of chemicals is higher and into the solution where the amount of chemicals is lower. For this experiment, I used the following materials: 15 slices from the same piece of suede, each slice is more or less the same size 3 test tubes, all the same sizes and with the same amount of tap water at the same temperature Test tube racks Beaker of water kept more or less at the same temperature (not near a heat source) Salt Tissue paper Measuring spoon: 1 teaspoon = gram Weighing scale Clamp Paper and pen for recording data Timer I decided to conduct the experiment in the following way. 1. Cut a piece of swede into 15 slices and placed the slices inside a container at room temperature and covered the container with a lid. 2. Poured tap water into each test tube labelled A, B, and C. 3. Used the clamp to pick up three slices of swede A, B, and C and weighed each slice using the scale. 4. Recorded the weight in grams. 5. Placed slice A of swede in test tube A; slice B in test tube B; and slice C in test tube C to soak in the solution. Waited for 5 minutes. 6. Used the clamp to pick up the soaked swede and weighed it. Recorded the weight of each slice A, B, and C in grams. 7. I then threw away the water in the test tube, cleaned the test tube, and dried it. 8. This test is repeated four more times. Steps 2 to 4 above were followed, but before step 5, I used a teaspoon to add salt to the water in the pan. I then mixed the water for 1 minute until the salt was dissolved before putting the slice of swede inside the test tube to soak for 5 minutes. 9. The amount of salt in each test was: a. Test 1 0 teaspoon b. Test 2 1 teaspoon c. Test 3 2 teaspoons d. Test 4 3 teaspoons e. Test 5 4 teaspoons The results of the experiment are shown in Table 1. The mass of each piece of swede before and after soaking in the solution is recorded in grams. The change in mass is recorded in grams. The amount of salt added to the water is also measured in grams. The time is measured in minutes. The temperature for the environment is recorded in degrees Celsius. The temperatures for the materials used in the experiment - the 15 pieces of swede, salt, and water - are kept constant and is measured in degrees Celsius. The temperatures of these items used in the experiment are kept constant because a change in temperature of any of these materials could affect the capacity of the swede to absorb water. From the table, it could be seen that as salt was added to the solution in the test tube, the weight of the swede changed. At Test 1, when there was no salt in the water, the change in the weight of the three pieces of swede was +40. At Test 2 after 1 teaspoon of salt was added to the water, the weight of the swede went down by 38. At Test 3 when 2 teaspoons were added, the weight of the swede went down by 30. At Test 4 when 3 teaspoons were added, the weight of the swede went down by 26. At Test 5, after 4 teaspoons of salt were added, the weight of the swede went down by 52. In Test 1, water moved from the pan to the swede, making the weight of the swede go up. In Tests 2, 3, 4, and 5, the water moved from the swede to the pan, making the weight of the swede go down. What I can conclude from the osmosis experiment are: First, when the amount of salt in the solution was zero, the water flowed from the solution to the swede. At this stage, there are more chemicals in the swede than in the solution. Second, when I added salt to the solution, the water flowed from the swede to the solution because there were more chemicals in the solution than in the cells inside the swede. The next part of the experiment would try to analyse the way the swede lost mass as more salt was added to the solution. As shown by Table 1, the swede lost 3.1% to 4.4% of its mass in Tests 2, 3, and 4, and then lost 6.2% of its mass in Test 5 after more salt was added. Table 1: Results of Experiment Weight in Grams Test Tube Salt Start Wt Total Test Final Total Test Change Total Change/ Test %-age Start Wt 1 A 0.0 2.84 7.68 2.98 8.08 0.14 0.40 5.2% B 0.0 2.00 2.09 0.09 C 0.0 2.84 3.01 0.17 2 A 0.5 3.61 9.21 3.51 8.83 -0.10 -0.38 -4.1% B 0.5 2.90 2.79 -0.11 C 0.5 2.70 2.53 -0.17 3 A 1.0 2.94 6.88 2.82 6.58 -0.12 -0.30 -4.4% B 1.0 1.88 1.78 -0.10 C 1.0 2.06 1.98 -0.08 4 A 1.5 3.12 8.27 3.05 8.01 -0.07 -0.26 -3.1% B 1.5 2.89 2.84 -0.05 C 1.5 2.26 2.12 -0.14 5 A 2.0 3.52 8.45 3.29 7.93 -0.23 -0.52 -6.2% B 2.0 3.27 3.04 -0.23 C 2.0 1.66 1.60 -0.06 [Source: Experiment Conducted] Bibliography Agashichev, S.P. (2005) Reverse osmosis at elevated temperatures: Influence of temperature on degree of concentration polarization and transmembrane flux. Desalination, 179 (1-3), pp. 61-72. AWWA (2007) Reverse osmosis and nanofiltration (AWWA manual), 2nd Ed. Denver, CO: American Waterworks Association. Cath, T.Y., Childress, A.E. & Elimelech, M. (2006) Forward osmosis: Principles, applications, and recent developments. Journal of Membrane Sciences, 281, pp. 70-87. Gilbert, S.F. (2000) Developmental biology, 6th Ed. Stamford, CT: Sinauer Publishing. Matthews, W.W. & Schoewolf, G.C. (1998) Atlas of descriptive embryology, 5th Ed. New York: Prentice-Hall. Tyler, M.S. (2000) Developmental biology: A guide for experimental study, 2nd Ed. Stamford, CT: Sinauer Publishing. Read More