...Investigating Osmosis in Potatoe Tissue To find out how the concentration of sucrose solution affects the rate of osmosis in a potato and what happens to the length and mass of the potato. What is osmosis? Osmosis is the movement of the water molecules across a partially permeable from a region of high water concentration to a region of low water concentration. Osmosis is a special case of diffusion The biochemical process in living cells always takes place in a solution. A solution is made up of a solvent (the dissolving fluid) and solute (the particles dissolved in the solvent). In living organisms, the solvent is water and the solution is called aqueous solution. Living cells are separated from their surroundings by the partially permeable cell surface membrane. The contents of the cell, the cytoplasm, are one aqueous solution and the surroundings of the cell, for example pond water, is another aqueous solution. If the two solutions do not have the same concentration of various substances, molecules may move away from one to the other by diffusion, if the membrane is permeable these substances. To summarise osmosis: The diffusion of water molecules, down a water potential gradiant across a partially permeable membrane. Cells and osmosis A cell is surrounded by a partially permeable membrane, and water may cross the membrane easily. If cell is placed in a solution of lower water potential, water leaves the...
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...Diffusion and Osmosis Jeveen Edmondson Micah Martello Rachel Mitchell Katelyn Lanier Biology Lab 152_26 October 21, 2010 Introduction Purpose: To show the different effects concentration gradients have on diffusion and osmosis across a selectively permeable membrane. Diffusion is the movement of a molecule from an area of high concentration to an area of low concentration. Osmosis is the movement of H20 from an area of high concentration to an area of low concentration across a selectively permeable membrane. Selectively permeable means that the membrane is regulating the passage of some substances while preventing others from entering the cell. The rate of diffusion or osmosis depends upon different factors. Diffusion rates depend on temperature, concentration gradients, and the size of the molecule that is trying to pass. Osmosis will depend up whether the membrane is permeable to water. In this experiment, the rate of diffusion or osmosis is based on the concentration gradient. The differences in the concentration gradient will either make for an isotonic, hypotonic, or hypertonic solution. Isotonic means that the concentration is equal inside and outside of the cell. Hypotonic means that there is a higher concentration outside of the cell than inside, so molecules would move from outside of the cell to inside the cell; and hypertonic means that there is a higher concentration inside the cell than outside, so molecules would move from inside...
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...What is reverse osmosis? What is reverse osmosis? Reverse osmosis is a special kind of diffusion. The word reverse means the opposite of the original direction of movement and osmosis is the movement of water molecules from where they are plentiful to less abundant over a selectively permeable membrane. Therefore, reverse osmosis can be define as when the solvent passes through the selectively permeable membrane from where they are less abundant to where they are in abundance. In other words, reverse osmosis is the flow water molecules opposing the natural direction of osmosis through a porous membrane. The reverse osmosis process happens after the osmosis process. Therefore, in order to fully grasp the process of reverse osmosis one has to understand the process of osmosis first. When a lower concentrated solution and a higher concentrated solution are separated by a selectively permeable membrane, water naturally moves across the membrane to the higher concentrated solution to dilute it. In time, the osmotic pressure will counter the diffusion process precisely and then the solutions will be at equilibrium. No net movement of water will be at this stage. This process is called osmosis. But, if there is an adequate amount of counter pressure applied to the concentrated solution to overpower the osmotic pressure, then osmosis will be reversed. The solution is now coerced through the selectively permeable membrane contrary to the natural flow of water. This is called...
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...purpose of this experiment was to demonstrate how diffusion and osmosis moves across a dialysis membrane. The sub-purpose was to determine if the sucrose solution, that was in dialysis tubing would leak into the distilled water. The hypothesis states that if a sucrose solution, in dialysis tubing, is placed into a beaker filled with distilled water the net movement of sucrose will be into or out of the dialysis bag. The null hypothesis states that if the sucrose solution in a dialysis bags mass may change after taking it out of the water each time to be weighted between each 15-minute increment 5 different times. After 15, 30, 45 and 60 minutes it can be concluded that weighing the sucrose solution in the dialysis bag increased in weight after each increment. Keywords: Diffusion, Osmosis, Dialysis bag, Sucrose solution, Distilled water Introduction...
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...diffusing across a membrane? requires passive transport requires no energy requires active transport requires both a and b Which correctly describes the plasma membrane? fluid and nonpermeable rigid and nonpermeable fluid and partially permeable fluid and completely permeable Which component of the phospholipid bilayer is considered hydrophobic? phospholipid head phospholipid tail phospholipid head and tail none of the above Which correctly describes the fluid-mosaic model of the cell membrane? phospholipid monolayer with embedded proteins phospholipid bilayer with embedded proteins phospholipid monolayer with embedded triglycerides cholesterol bilayer with embedded proteins This process uses a carrier protein...
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...Clara Skepple Miranda Wilby, Sarah Cavanagh Thursday, March 3 2016 Observing Diffusion and Osmosis INTRODUCTION: Related Theory: The cell membrane is the outermost boundary of the cell, made up of proteins and lipids. This membrane holds the cell together and establishes the movement of materials that go into and out of the cell. This is a selectively permeable membrane: a barrier that allows some molecules to pass through, but prevents other molecules from penetrating (1). Passive transport is the movement of materials across a cell membrane without the use of energy from the cell. One type of passive transport is diffusion. Diffusion involves the movement of molecules from an area with a higher concentration to one with a lower concentration (1). Diffusion is affected by many things; temperature, concentration and pressure. It disperses until molecules are equally distributed within a space. Osmosis is diffusion of water through a selectively permeable membrane. Water will diffuse from the place with higher concentration to the place with a lower concentration. Water goes through the concentration gradient. Which is when molecules without energy diffuse from the place with higher concentration to the one with lower (1). The ability to diffuse through water all depends on the size of the molecule as well. For example, starch is a large molecule therefor it should not fit through the cells membrane. Starch is a polysaccharide because it is comprised of lots of sugars. Individually...
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...Diffusion and Osmosis Diffusion is the passive movement of molecules or particles along a concentration gradient, or from regions of higher to regions of lower concentration. Osmosis is a type of diffusion. This is the diffusion of water through a selectively permeable membrane (chooses what comes in and what goes out) from a region of higher water potential to a region of lower water potential. Water potential is the measure of free energy of water in a solution. Unlike diffusion, osmosis requires ATP to move the particles across the membrane. Hypothesis: In both experiments diffusion and osmosis will occur between the solutions. In experiment 1A the tube of glucose/starch will absorb the iodine solution in the cup. In experiment 1B the tube of distilled water will lose weight, and the tube of glucose will gain weight. The purpose of the experiments is to differentiate which test was diffusion and which was osmosis. Materials: Experiment 1A: Plastic Cup, Plastic Pipet, Iodine-Potassium Iodide, Deionized Water, Glucose Paper Strip Experiment 1B: (3) 15 cm pieces of Dialysis Tubing, beaker, 15 cm piece of white thread, 80% Glucose, 2% Starch, Plastic cup, 10% glucose, 15 cm blue thread, distilled water, 15 cm red thread, 20% glucose Procedure Experiment 1A: First cut a 15-cm length of dialysis tubing. Place the dialysis tubing in a beaker of distilled water and allow it to remain in the beaker for 1 minute. Open the dialysis tube by rolling it in between thumb...
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...demonstrating differential permeability Part B: A model for osmosis Aim: To observe and record the effects a differentially permeable membrane has on the process of diffusion. To observe and examine the process of osmosis. Partner: Phil Reichelt Results: Part A demonstrating differential permeability Table 1 results of test: | Water in tube at start of experiment (distilled water) | Water in tube at start of experiment (distilled water) | Water in tube at end of experiment | Water in tube at end of experiment | | clinistix | Iodine test | clinistix | Iodine test | Results | Glucose not present in deionised water | Starch not present deionised water | Glucose present in external deionised water | No evidence of starch being present | interpretation | The water is not contaminated | The water is not contaminated | Glucose has diffused through the membrane | No change | Part B results shown on the following page Discussion: PART A – 3) a. The two substances present in the dialysis bag at the start of the experiment were glucose and starch. In the solution outside the dialysis bag, we later found the presence of glucose, indicating it had moved from the inside of the dialysis bag into the external deionised water. The reasons for glucose being able to penetrate the membrane is because glucose is a monosaccharide molecule (simple sugars) and a small enough to pass through the pores of the membrane ( dialysis bag). b. The difference between the glucose and...
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...Diffusion and Osmosis: A Full Analysis on the Concentration of Solutes and the Molecular Weight of Substances in a Dialysis Tubing and Potato Experiment Alejandro Gonzalez October 30, 2012 Biology 1500 Professor Raja Abstract The purpose of the diffusion and osmosis lab experiments is to determine the contents present before and after leaving a dialysis tubing in a beaker of solution and to test water potential by determining the percent change in mass of potatoes when left in different concentrations of sucrose in numerous beakers. In the first experiment, what occurred was that we put contents into the dialysis tubing and in a solution in a beaker and we were to set the tubing in the beaker for a set amount of time and see what contents are present in the beaker and in the dialysis after the amount of time. In the second experiment, we were to test if a mass change would occur if we set potatoes in different concentrations of sucrose. My alternate hypothesis in the first experiment with the dialysis tubing was accepted due to the fact that glucose and sodium sulfate diffused across the pores of the tubing, but starch and protein could not be. My alternate hypothesis in the second experiment was also accepted due to the fact that there was a mass change in the potatoes when put in different concentrations of glucose. Introduction Diffusion and osmosis are two terms that actually coincide with each other in the big picture and in this particular set of experiments...
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...Lab #6 Diffusion, Osmosis, and Tonicity Group #3 Section A3 Group Members: Laghu Shakya, Alex Maican, Kelvin Chen, Ziye Lin 10/18/2015 Abstract: In this lab we will be gaining an understanding of how transport in membranes work. This is important because in our semi permeable cell membrane the mode of movement relies on transport. Some methods of transportation for molecules are simple diffusion, facilitated diffusion, active transport, exocytosis and osmosis. The reason molecules tend to move around when dissolved in a solution is because all molecules display random thermal motion and have kinetic energy. Kinetic energy is what allows the molecules to diffuse down a gradient of high concentration to regions of low concentration until the distribution of molecules become equal and achieved dynamic equilibrium. The entire solution only becomes homogeneous when one of the several factors are reached: the size of the dye molecules, temperature of the solution, density of the solvent and concentration of the dye. Heat is what causes random motion of molecules and passively moves molecules in biological systems. However, we can’t see this movement with our naked eye. In order for us to see this movement, we must use a microscope to see the small particles move after collision, this is called the Brownian movement. When talking about the cell membrane we must understand that it is selectively permeable, which means it can choose what can pass through the membrane and what...
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...make up the membrane. It confines the cell organelles from the extracellular area. The cell can manage its own environment. The phospholipid bilayer controls what enters and exits the cell, with the aid of transporter proteins and channels. However if the internal cell environment is not performing correctly then the channels will...
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...require energy, diffusion, facilitated diffusion and osmosis are included in this. Active transport is a process which does need energy to function. Endocytosis and exocytosis are examples of this. Diffusion and the factors affecting how well it can occur will also be talked about. http://chemwiki.ucdavis.edu/@api/deki/files/26918/=17.6.new.jpg?revision=1 The phospholipid bilayer is a structural component that makes up all cell membranes. The lipid bilayer is named so because there are two layers of fat cells within the membrane. They are made up of a glycerol backbone with a phosphate group and two fatty acid chains attached to it. The phosphate group is polar while the fatty acids are no polar. Phospholipids are the main molecules found in the plasma membrane. The plasma membrane protects the interior of the cell which also has selective permeability. Most of the cell membrane is impenetrable to water soluble substances as it’s made up of lipids. Those water soluble substances and other molecules can pass through the membrane when it is made up of proteins. They can pass through by a channel protein or carrier protein. Cells need a membranes in order to control what substances go in and out. It also compartmentalises individual cell processes by containing the contents and organelles of the cells. Because of the bilayer, communication with the external environment can be achieved. This is also the site where many chemical reactions can take place. The membrane can allow the...
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...Effects on rate of Osmosis across a selectively permeable membrane for varying starch solute concentrations and water mixed with Lugol’s Iodine The contents of this document pertain to the effect of particle (starch) concentration on the rate of Osmosis through a selectively permeable membrane made visible by the use of Lugol’s Iodine indicator. The results proved that the greater the concentration of the starch solute within the membrane, the greater the rate of osmosis and change in color of the solute due to an increase of Lugol’s Iodine diffusing into the membrane and reacting with the starch. Ruba Nizam 3/18/2014 Introduction The purpose of this lab is to test the rates of osmosis on a model of a selectively permeable membrane filled with varying levels of starch concentrations using dialysis tubing. This experiment will make it possible to see how particles move from an area of high concentration to an area of low concentration due to the use of Lugol’s Iodine indicator. According to Michael McKinley, osmosis is defined as the, “movement of water molecules across a membrane from an area of high water concentration to an area of lower concentration until equilibrium” (McKinley). Diffusion is related to the movement of particles from an area of high concentration to an area of low concentration. Osmosis and diffusion are both passive transports that do not require energy although osmosis is the diffusion of water (Balmer). These transport processes occur across...
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...In our lab, we were able to witness the process of osmosis and diffusion through dialysis tubing, starch, glucose, iodine, and water. The reason we chose to use these materials is because the dialysis tubing could act as a selective permeable cell membrane to view which molecules are able to pass through and which weren’t. We used the starch, since it is a polymer, and found out that it could not pass though the membrane. We used the glucose, which is a monomer, and found that it was easily able to go into a state of equilibrium with the water. The monomer was able to pass through the dialysis tubing due to its small size and the polymer was not due to its large size. This was what we had predicted in our hypothesis except for the fact that although the glucose did pass through the membrane it did not completely pass through only some of it to create equilibrium. In the starch and iodine solution it was the iodine which was allowed to pass thought the starch was not able to due to its large size further explaining why the water had eventually turned almost clear again compared to its brown looking initial state and the inside of the membrane had turned almost completely blue compared to the clear color it was before. When measuring the glucose both inside and out of the membrane we found that they both had some glucose in it, and although we could not visibly see the changes, it was noticed that the diffusion had occurred and since there was some glucose in each it is safe to...
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...Osmosis of Water Biology 105 Lab 3/22/11 Introduction Cells have kinetic energy, a source of energy stored in cells. This energy causes molecules to bump into each other and move in new directions. Diffusion is one result of this molecular movement. Diffusion is the random movement of molecules from an area of higher concentration to areas of lower concentration. Osmosis is a special kind of diffusion where water moves through a selectively permeable membrane that only allows certain molecules to diffuse though (Lab Manual 7e, 2010). Diffusion or osmosis occurs until dynamic equilibrium has been reached. This is the point where the concentrations in both areas are equal and no net movement will occur from one area to another. If two solutions have the same solute concentration, the solutions are said to be isotonic. If the solutions differ in concentration, the area with the higher solute concentration is hypertonic and the area with the lower solute concentration is hypotonic. Besides osmosis and diffusion, molecules and ions can be moved by active transport. This process includes the use of ATP (adenosine tri-phosphate) to drive molecules in or out of a cell. Active transport is generally used to move molecules against a concentration gradient, from an area of low concentration to an area of higher concentration of molecules. The purpose of this experiment was to show that osmosis of water thru plant stomata does not require energy (ATP)...
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