Diffusion And Osmosis Abstract In this Diffusion and Osmosis lab a total of three experiments were performed. For experiment 5. 1 we investigate diffusion through a selectively permeable membrane and the many factors that influence the rates of diffusion. In experiment 5. 2 we investigate both animal and plant cells in different molar solutions and the different osmotic behaviors within the cells. In experiment 5. 3 we test the osmolarity of plant cells through the usage of potato tuber cells. In experiment 5. in order to observe diffusion we examine the Brownian movement by observing carmine on a wet mount slide, and by using dialysis tubing, we investigate the selective permeability to reducing sugar, glucose, starch, and iodine potassium iodine. In experiment 5. 2 we use samples of ox blood and Elodea plant to observe the net flow of water from the surrounding solution into the cells. In experiment 5. 3 in order to estimate the osmolarity of the potato tuber cells we use the methods of change in weight and change in volume.
In experiment 5. 1 while observing the wet mount, the Brownian movement of the carmine particles are never ending and show no pattern. While investigating the permeability of the dialysis tubing through the Benedict’s test, the solution inside of the bag (glucose), was originally clear, but after the Benedict’s test turned a strong orange color, finally ending with a final color of dark blue-black. In experiment 5. 2 while observing the ox blood under the microscope the cells underwent either lysis or shriveled up.
When observing the Elodea cells in distilled water and separately in salt water, the appearance and condition of the cell drastically changed. When the Elodea cell was placed into the distilled water, the cell became swollen and underwent lysis. However, when the Elodea cell was placed into salt water, the cell shriveled up and appeared bumpy. In experiment 5. 3 when placing the potato segments into different molarities of sucrose a trend appeared. With a higher sucrose molarity, the potato segment gained less and less weight until eventually, the potato lost weight.
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In experiment 5. 1, using this information we discovered from the wet mount, we concluded that smaller particles move more rapidly than larger particles. In the dialysis tubing experiment we determined from the color changes in and outside of the bag that iodine and glucose are smaller particles able to pass through the tubing, while the starch is unable to do so because of its larger particle size. Iodine was absorbed into the tubing, turning the solution into the resulting blue-black color. In experiment 5. we determined that when the animal cell is placed in a hypertonic solution, water left the cell making the cell shrivel up and appear bumpy, or crenate. However, when the animal cell is placed in a hypotonic solution, water enters the cell and undergoes lysis, making the cell swell and eventually burst. When observing the Elodea plant, we determined that the distilled water was the hypotonic solution and the salt water was the hypertonic solution and had a higher OAS. We determined that the preferred way of living for plant cells is in either an isotonic or hypotonic environment.
In experiment 5. 3 we determined that as the sucrose molarity increases, less weight is gained by the potato, until eventually, the potato segments lose weight and their percent weight change becomes negative. Introduction In this lab, we observe the process of diffusion and osmosis. In the process of diffusion, molecules spread from an area of higher concentration to an area of lower concentration. When the molecules are even throughout the area, this is called equilibrium. Osmosis is the diffusion of water across a membrane. In osmosis water will move towards the higher concentration of solute.
Diffusion and osmosis are both type of passive transport, meaning that no energy is required for the molecules to move into or out of the cell (Lewis, M. ). There are three types of solutions or environments in which cells can be submerged in: Isotonic, Hypertonic, and Hypotonic. In an isotonic solution, the concentrations inside and outside of the cell are both equal to each other. The net movement of water moves back and forth in equally, making the term “iso” meaning the same. In a hypertonic solution, the concentration outside of the cell is higher than that inside of the cell.
This causes the water to exit the cell, making the cell shrivel up and shrink. If either animal or plant cells shrivel up and shrink, the cell may die. Finally, in a hypotonic solution, the concentration inside of the cell is higher than that on the outside. This causes the cell to gain water and grow larger. The difference is that plant cells may become enlarged, but are unable to burst due to the cell wall. Animal cells however are in danger of bursting, but the contractile vacuole will attempt to pump out the access water. Since substances move from a region of high concentration (more solute) to low concentration (less solute), remember that solutes will always move from a hypertonic solution to a hypotonic solution or solvents will always move from a hypotonic solution to a hypertonic solution. ” (Wayne, R. )
During the experiments, diffusion and osmosis occur until dynamic equilibrium is reached. Plant cells will undergo the process of increased turgor pressure or plasmolysis, while animal cells may undergo crenation or lysis. Experiment 5. 1 Part A: I hypothesize that the movement of the single carmine particles, which are small, will have no given pattern and move more rapidly than that of larger particles. Experiment 5. 1 Part B: * I hypothesize that the I2KI will be absorbed into the tubing, changing the color of the solution inside the tubing. I also believe that the glucose will not move because the particles will be too large to bypass the dialysis tubing membrane. Experiment 5. 2 Part A: * I hypothesize that when the animal cell is in a hypertonic solution, water will leave the cell and cause it to undergo crenation.
However, if the cell is in a hypotonic solution, water will enter the cell and the cell will undergo lysis and explode. Experiment 5. 2 Part B: * I hypothesize that when the Elodea plant cell is placed inside of the hypertonic salt solution the cell will shrivel up and may undergo plasmolysis. However, if the Elodea cell is placed in a hypotonic solution, it will result in an increased turgor pressure. Experiment 5. 3 * I hypothesize that the potato segment will gain weight when in a hypotonic solution. The potato segment should also lose weight while in a hypertonic solution.
I believe that the higher the sucrose concentration, the more weight will be lost. These experiments are in order to determine the process of passive transport, osmosis and diffusion. The experiments will provide information and demonstration of molecules moving from an area of higher concentration to an area of lower concentration. We will learn how and why diffusion and osmosis happens in all living things. I predict that examining cells in hypotonic and hypertonic solutions will provide us with information about how cells react and how they return to their normal isotonic state.
The methods of each experiment will allow us to see how animal cells undergo crenation and lysis, while plant cells undergo increased turgor pressure and plasmolyisis. Examining cells under the microscope will give us an in-depth look into how animal and plant cells react in hypotonic, hypertonic, and isotonic solutions. Enabling us to learn how dynamic equilibrium is reached through diffusion and osmosis. Materials and Methods In experiment 5. 1 the following materials are required in order to carry out the procedure: Part A: Dropper bottle of water, slide/cover slip, compound microscope, dissecting needle, and carmine powder.
Part B: String, 500-mL beaker (1/3rd filled with water), handheld test tube holder, 3 standard test tubes, transfer pipettes, two 400-mL beakers to hold dialysis bag, 30-cm strip of moist dialysis tubing, wax pencil, 30% glucose solution, starch solution, Iodine potassium iodide solution, Benedict’s reagent, and a hot plate. In experiment 5. 2 the following materials are required in order to carry out the procedure: Part A: Test tube rack, three test tubes with screw caps (each containing one of three unknown solutions), dropper bottle of ox blood, newspaper or other printed paper, 4 clean microscope slides and cover slips.
Part B: Compound microscope, 1 slide of Elodea in a hypertonic salt solution, 1 slide of Elodea in distilled water. In experiment 5. 3 the following materials are required in order to carry out the procedure: Part A: 1 potato, 1 large potato tuber, seven 250-mL beakers, marking pencil, forceps, balance weighing to the nearest 0. 01 gram, aluminum foil, petri dish, razor blade, cork borer, deionized water, paper towels, metric ruler, calculator, sucrose solutions (0. 1, 0. 2, 0. 3, 0. 4, 0. 5, 0. 6 molar) In experiment 5. 1 the dialysis tubing was filled with glucose and placed into a beaker of Iodine potassium iodide solution.
The control of water was placed to the side until need for the Benedict’s test. After approximately thirty minutes the color of the glucose inside of the bag turned from clear to a dark blue-black color. While the iodine potassium iodide solution inside the beaker did not change color. After the Benedict’s test, the contents inside of the bag turned orange, while the solution inside the beaker turned to a lighter shade of orange. The control remained unchanged until after the Benedict’s test turned the solution a light shade of blue.
In experiment 5. both the animal cells and plant cells were placed into hypertonic and hypotonic solutions. When the animal cell was placed into a hypertonic solution, the cell shriveled up and had a higher OAS. As the animal cell was placed into a hypotonic solution, the cell underwent lysis and eventually burst. The control was placing animal cells by themselves without any unknown solution. In experiment 5. 3, placing the potato segments into various sucrose molarities caused both weight gain and loss. The control was placing a segment of potato into a solution with a sucrose molarity of zero, and resulted in a 10% weight gain.
The independent variable was the sucrose molarity, which ranged from 0. 0 to 0. 6 molar. The dependent variable was percent change in weight of the potato segments. In experiment 5. 1 part A: * Obtain all of the materials and prepare the wet mount by adding a single drop of water to a clean slide. * After adding the carmine to the slide by means of the dissecting needle, observe the slide under a compound microscope. * Begin by observing on low power, and then onto high power. * After your observations are complete, record the results and draw conclusions based on the results.
In Experiment 5. 1 part B: * Prepare the dialysis bag by moistening the bag and adding 4 full pipettes of 30% glucose and 4 full pipettes of starch solution into the bag. * After sealing the bag, add 300-mL of water and several drops of iodine potassium iodide solution, until yellow, into a 500-mL beaker. * Record the color of the water and iodine potassium iodide in the data table. * After leaving the bag in the beaker for at least 30 minutes, remove the bag and record the color of both the inside the bag and inside the beaker. * Label three test tubes: control, bag, and beaker. Add 2 full pipettes of water into the control tube. * Add 2 full pipettes of the bag solution into the bag tube. * Add 2 full pipettes of the beaker solution into the beaker tube.
* Add a single drop of Benedict’s reagent into each test tube. * Heat the test tubes in boiling water for three minutes and record your observations. In experiment 5. 2 part A: * Observe the three test tubes of unknown solutions and blood and record what you see. * Gather four clean slides and label them A, B, C, and D. * Place a drop of blood on slide D, and observe the shape of red blood cells without treatment. Place a drop of solution A onto slide A and add a small drop of blood to the edge of the cover slip. * Repeat with solution B and C with their respective slides. * Record your observations.
In experiment 5. 2 part B: * Prepare the wet mount slide with the Elodea sample. * Observe the Elodea in both solution A and B. * Record what you see the cells do under the microscope into the provided data table. In experiment 5. 3: * Begin by cutting out seven cylinders of potato. * Record the initial weight of each piece and then transfer the potato pieces to the water beaker with the given sucrose molarity starting at 0. 0 and ending with 0. molar. * After incubating for 1. 5 to 2 hours, blotch the potato pieces with a paper towel and record their weight after being gently dried off. * Calculate the percentage change in weight by dividing (weight change/initial weight) x 100). * Record your observations and data in the designated data section. Results In experiment 5. 1 part A: (Plant cell in Hypotonic, Hypertonic, and Isotonic Solution) In experiment 5. 1 part B: Solution Source| Original Contents| Original Color| Final Color| Color After Benedict’s Test| Bag| Glucose| Clear| Blue-Black| Orange| Beaker| I2KI| Light Brown| Light Brown| Light Orange|
Control| H2O| Clear| Clear| Light Bluw| In Experiment 5. 2 part A: (Animal Cell in Hypertonic, Isotonic, and Hypotonic Solution) In Experiment 5. 2 part B: (Appearance of Elodea Cells in Solutions “A” and “B”) Solution| Appearance/Condition of Elodea Cells| A- Distilled Water| Cell became swollen and burst (Lysis)While others only underwent increased Turgor. | B- Salt Water| Cell shriveled up and appeared bumpy. | In Experiment 5. 3: Sucrose Molarity (Molar) x Percent Change in Weight (grams) Discussion/Conclusions The data collected from each experiment proved my hypotheses to be correct.
All supporting evidence proved our ideas to be true. Through the data tables and graphs given above, our conclusions were spot on when compared to our hypotheses. In experiment 5. 1 we believed that the particles of starch were too large to move through the dialysis tubing, however, the glucose and I2KI molecules would be small enough to be able to pass through the selectively permeable membrane. Our results proved our hypothesis to be correct. In experiment 5. 2 we believed that when the animal cells are placed in a hypertonic solution, that the cell would shrivel up and undergo crenation.
Yet, if the animal cell were in a hypotonic solution, it would swell, and go through lysis. On the other hand, if plant cells were placed in hypertonic and hypotonic solutions, they would undergo plasmolysis and turgor respectively. Our observations of the ox blood and Elodea plant proved to be correct when examined under the microscope. In experiment 5. 3 we predicted that as the sucrose molarity increased, the percent change in weight of the potato would decrease. We were able to see this trend after gathering our data in our table and transferring that information in the graph provided above.
The results that we produced in each experiment matched up with our predictions. We did not receive any unexpected errors or problems during our lab experiment. Our results as we predicted did match up with our pre-lab research and hypotheses. We were able to determine these results through our understanding of the net movement of water to and from the cell. Diffusion and osmosis are forms of passive transport, and with no requirement of energy, we were able to replicate the procedure through our lab work understanding.
A slight problem that I found was with experiment 5. 3. After placing the potato segments into their designated sucrose molarities, upon taking them out of the beaker, the potatoes were too fragile and could have been dried out for a significant more amount of time to truly see their change in weight percentage. With the potato segments even being moist, the slightest amount of moisture or water could drastically change the actual weight of the final potato segment. That was however a minor issue and the experiment did prove for my hypothesis to be correct.
I did not have any other problems or issues during the other experiments. Upon conclusion of the three experiments, our pre-experiment hypotheses were in fact correct. We were able to see both diffusion and osmosis in work through the eyes of the microscope. During experiment 5. 1 we were able to see the process of osmosis through the dialysis tubing. Experiment 5. 2 showed what happened to both plant and animal cells when placed in hypotonic and hypertonic solutions. We were able to see first hand the process of lysis, crenation, plasmolysis, and turgor. Finally, in experiment 5. , the potato segments showed how when placed in a higher molarity of sucrose, the less weight the potato is able to gain, until it began to lose more and more weight. Through the graph we designed, we were able to easily determine the osmolarity of the potato tuber tissue.
In conclusion, all three of our experiments were a success and gave us an in depth look and understanding on the processes of diffusion and osmosis. Literature Cited (References) * Lodish, H; Berk, A; Kaiser, C; Scott, M; Ploegh, H, Bretscher, M. 2007. Molecular Cell Biology, Freeman, United State of America. Wayne, R. 2009. Plant Cell Biology: From Astronomy to Zoology, Academic Press, United States of America. * Lewis, M. 1997. Diffusion, Osmosis, and ATP. Pp. 176-182 in Mallinson, J et al. eds, Integrated Science: Horizons (6th edition), Ginn, New Jersey. * Miller, S. 2006. Animal Cells and Their Function. Pp. 126-148 in Castro, B et al. eds, Zoology (7th edition). McGraw-Hill, Texas * Morgan, G; Carter, M; Dickey, J. 2010. Investigating Biology, Pearson, United States of America. * Cambell, N; Reece, J. 2007. Biology (8th edition), Cummings, United States of America.
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