...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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...Introduction Osmosis is a key for every living organism on Earth, from humans to plants. In this lab we examined the processes of osmosis and diffusion. Osmosis is a specialized type of diffusion; “it is the process of water moving across a semi-permeable membrane, in response to a concentration gradient” (Readel, 2000). Fluid passes both in and out of the semi permeable membrane in osmosis, but usually there is a “net flow in one direction or another, depending on which side of the membrane has a higher concentration of solutes” (Smith, 2013). There are different factors that can affect the rate of osmosis such as temperature. In one experiment, my group and I used dialysis tubing to simulate a cell membrane. This tubing was filled with molasses and was immersed in water; cold, warm and hot. The bags were removed at regular intervals and measured for the amount of osmosis that occurred. We observed that the bags in the hot water experienced the highest amount of osmosis. In warmer temperatures the water particles tend to diffuse from high to low concentration, thus trying to dilute the solute concentration from the solution outside. From these observations and conclusion, my group and I hypothesized for our own experiment the level of solute concentration will affect the rate of osmosis. Diffusion is the process of “any substance moving from a region of high concentration to a region of lower concentration” (Readel, 2000). Therefore we predicted that the higher concentration...
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...Demonstration of Osmosis using visking tubing Aim The aim of the experiment is to demonstrate the effects of osmosis using visking tubing, warm water and sucrose solution. Method Test tube A on the inside is hypertonic because there is a more concentrated solute, on the outside it is hypotonic because there is a less concentrated solute. Test tube B is isotonic both on the inside and outside. Test tube C on the inside is hypertonic and on the outside is hypertonic. Experiment During the experiment 3 test tubes were placed in a wire rack, the test tubes were then labelled A, B and C. Tube A was half filled with 0.1M sucrose solution whilst tube B was half filled with 0.5M sucrose solution, tube C was half filled with 1.0M sucrose solution. Three lengths of visking tubing were soaked in warm water for two minutes. One piece of visking tubing was three quarters filled with 0.5M sucrose solution and knotted at either side, it was then rinsed to get rid of any sucrose solution on the outer tubing. The visking tubing was then dried and weighed. The same was done with test tube B and C. After 10 minutes the cell models (visking tubing) were removed from the test tubes and dried and weighed. The results were recorded and the cell models were returned to the test tubes. After 20 and 30 minutes the same thing was done and results were recorded afterwards. Tube | Start | 10 Minutes | 20 Minutes | 30 Minutes | A | 19.16g | 18.29g | 19.81g | 20.13g | B | 14.81g |...
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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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...includes selective transportation of molecules and cell-cell gratitude. The passive process of the plasma membrane doesn’t use energy to move substances down their absorption grade. Active transport process of the plasma membranes processes use energy to move substances across the membrane. Osmosis Lab 2. Explain your observations in detail in terms of concentration gradient, diffusion, osmosis, osmotic pressure, passive transport, and active transport. A. The osmosis lab was a really awesome lab. It gave you the excitement for three days to see how much the egg has changed. Concentration gradient is a ongoing change in the concentration of solutes in a solution as a function of distance through a solution. The concentration gradient of the egg was almost seeing through. You could see the eggs membrane and the yellow oak that was in the center of the egg. Diffusion is the tendency of atoms, molecules, and ions in a liquid or air solution to move from areas of higher concentration to areas of low concentration to become more diffuse. For the diffusion of the egg, the egg expanded and got higher concentration of the water outside of the membrane and a lower concentration inside the osmosis. Osmosis is the movement of water across a selectively permeable membrane into a...
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...Practice Problems – Osmosis and Water potential Use this key to answer all the problems below. If you choose B or C, rewrite the statement so that it is complete and true. A = TRUE B = FALSE C = NOT ENOUGH INFORMATION PROBLEM ONE: The initial molar concentration of the cytoplasm inside a cell is 2M and the cell is placed in a solution with a concentration of 2.5M. 1. Initially, free energy is greater inside the cell than outside 2. It is possible that this cell is already in equilibrium with its surroundings. 3. Initially, solute concentration is greater outside the cell than inside. 4. Water will enter the cell because solute potential is lower inside the cell than outside. 5. The cell will become flaccid because the pressure potential is greater outside the cell than inside. 6. The cell is already in equilibrium with its surroundings because of the combination of pressure potential and solute potential inside and outside the cell. 7. Initially, the cytoplasm is hypertonic to the surrounding solution. 8. Initially, the numerical value of the solute potential is more negative inside the cell than outside. 9. Net diffusion of water will be from inside the cell to outside the cell. 10. At equilibrium, the molarity of the cytoplasm will have increased. 11. At equilibrium, the pressure potential inside the cell will have increased. PROBLEM TWO: The initial molar concentration of the cytoplasm inside a cell is 1.3 M and the surrounding solution is...
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...Introduction: Water is the body’s prime solvent. In essence, the movement of water and solutes though cell membranes is an integral characteristic of physiology. Osmosis is a passive process that involves the movement of water across a membrane down a concentration gradient (Marieb, 2012). If a cell membrane is differentially, or selectively permeable, both water and solutes will move down their concentration gradients. Conversely if a cell membrane is impermeable, only water can move across it down a concentration gradient (Marieb, 2010). Varying osmotic gradients can affect the volume of a cell when it is placed in solutions of different concentrations. Hence, osmosis affects tonicity, which is a concept that refers to the way the movement...
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...In an isotonic environment, solute concentration and water are equal inside and outside the cell. Water goes in and out of the cell at an equal rate. With a hypotonic environment, the water concentration is greater outside the cell, with solute concentration higher inside. Water moves into the cell. In a hypertonic environment, water concentration is greater inside the cell, with the solute concentration higher outside the cell. Water moves out of the cell. Microbe’s reaction to the changes in osmotic pressure determines their viability in the environment. Isotonic or slightly hypotonic environments usually are best for optimal growth of bacteria. Some microbes can survive in different osmotic conditions and can survive in hypertonic conditions like salt water. They have adapted to the changes in osmotic conditions. Staphylococcus. Epidermidis in 1% NaCl solution had a large amount of growth and the solution was slightly cloudy, 4% NaCl solution had moderate growth, 10% NaCl solution had a small amount of growth. Saccharomy cerevisiae in 1% NaCl solution had a moderate amount of growth with the solution cloudy throughout, in 4% NaCl solution with minimal growth with the growth adhered to the side of the tube, scant amount of growth in the 10% NaCl solution. The test showed that S. epidermidis and S. cerevisiae can grow in concentrations of NaCl because both have adapted to the effects of NaCl in response to the osmotic pressure. The higher concentrations NaCl had the least...
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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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...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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...Brad Sanford Bio 1120 Section 6 September 17, 2013 Partners: Dominique & Carleigh Lab #2: Osmosis & Diffusion Introduction Diffusion is the movement of molecules from a high concentration gradient to a low concentration gradient. This can occur in gases, liquids, and solids. Osmosis is a type of diffusion that allows water molecules to move through a semipermeable membrane freely by way of passive transport. During osmosis a semipermeable membrane will allow small water molecules to pass through freely without any help but larger molecules like proteins will not move through the semipermeable membrane without active transport. Active transport requires a chemical energy like ATP (adenosine triphosphate) to help the larger molecules move through the cell’s membrane.(Krane) When describing high and low concentrated solutions, it is useful to understand the terms hypertonic, hypotonic, and isotonic. A hypertonic solution has a higher concentration of solutes compared to a lower concentrated solution as water will move out of the solution (Dehydration). A hypotonic solution has a lower concentration of solutes compared to a solution with a higher concentration of solutes and water will move into the solution (Swelling). In a isotonic solution the solutes are at an equal concentration and there is no movement of the water. In this lab, two experiments were performed. The first one uses a small plastic bag closed up and filled with cornstarch and distilled water...
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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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...Introduction Water can diffuse across the partially permeable membrane of cells depending on the concentration difference between the inside and the outside of the cells. You are going to look at the effect of different concentrations of sugar solutions on potato cells. By measuring the mass of the potato cylinders, you will be able to find out if water has entered or left the potato cells. Aim To find out what happens to the mass of potato cells when they are left in increasingly concentrated solutions. Hypothesis My hypothesis was that if the concentration of sugar where the water potential is higher than the water potential of the potato, the mass of the potato will increase. On the other hand, if they have similar water potential, the mass will not change. Variables Independent variable: concentration of sugar Dependent variable: change of mass of the potato before and after the experimant Controlled variable: temperature Apparatus • Potato • A 6mm Cork borer • Ruler • Scalpel • White tile • Sugar • Distilled water • Labelling pen • 50mL measuring cylinder • Weight balance • Stopwatch • Labels • Paper towel • 12 boiling tubes • Boiling tubes rack • Four 250mL beakers Methods 1. Measure 100mL of distilled water into a 250mL beaker. Label it “0% sugar solution”. 2. Measure 100mL of distilled water into a third 250mL beaker. Add 20g of sugar into it and stir until fully dissolved. Label it “20% sugar solution”. 3. Measure 100mL of distilled...
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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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...in a cell. It allows oxygen and carbon dioxide exchange in the lungs and between the bodies of intracellular fluid and cells. An example of this process is the diffusion of a smell in a room. Eventually dynamic equilibrium will be reached. This means that the concentration of the molecules carrying the smell will be approximately equal through out the surrounding enclosed area and no net movement of the molecules will occur from one area to another. Osmosis has to deal with the movement of water molecules. It is the diffusion or movement of water through semi-permeable membranes from a region of higher water potential (hypotonic solute) to a region of lower water potential (hypertonic solute). Water potential is the measure of free energy of water in a solution. The movement of water across the cell membrane depends on the concentration of solutes on both sides of the cell membrane. When water moves out of the cell, the cell will shrink. When water moves into the cell the cell will expand and possibly burst. Diffusion and osmosis are not the only processes responsible for the movement of ions or molecules in an out of cells. Active transport is process that uses energy from ATP to move substances through the cell membrane. Active transport moves a substance against its concentration gradient, that is to say from a region of low concentration to an area of higher concentration. Procedure 1A Obtain dialysis tubing that has been submerged in water. Tie off on of the ends to form...
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