Biology Lab on Osmosis

Purpose: The purpose of this lab is to familiarize you with osmosis and, specifically, what happens to cells when they are exposed to solutions of differing tonicities.

The Osmosis and Diffusion lab was conducted to provide us with information on how built up mucus affects those conflicted by the recessive genetic disease, Cystic Fibrosis., due to a mutation to the membrane regulating chloride (Cl-). This mutation prevents the Cl- from leaving the cell causing the amount of sodium (Na+) in epithelial cells, which results in extreme mucus on the lungs and airways causing this disease to be fatal if not treated but treatment does not equate to a long lifetime. During the lab we took the data from three parts: Diffusion, Osmosis in an Elodea Cell, and finally the Role of Osmosis in Cystic Fibrosis. During Part 1 we looked at diffusion across a semipermeable membrane for starch and glucose, which resulted in both having a negative solution when placed in a semipermeable membrane. Then we looked at osmosis in the Elodea Cell to watch for the occurrence of Plasmolysis, when a cell’s plasma membrane pulls away from the cell, and how a plant cell is affected by both hypertonic and hypotonic solutions. Finally, we observed the role of Osmosis in Cystic Fibrosis using dialysis bags to represent a normal cell and a Cystic Fibrosis cell with the normal containing 1% NaCl while the Cystic Fibrosis bag contained 10% NaCl. After we ran the experiment, we looked at the Percent Change in Mass and compared them after 30 minutes. We found that Cystic Fibrosis cells didn’t change mass as much as the normal cell ending with a change in mass over -1%. The

Table 1 shows the contents of the bags and the content of the concentration it was submersed in. Bags 2-4 each contain a solution of both sucrose and water. These bags were each put into beakers containing hypertonic solution. These bags gained weight over time because the water moved from its high concentration inside the beaker to the low concentration inside the membrane of the artificial cell, the membrane being the bags that consisted of dialysis tubing. The

Water diffuses across the membrane from the region of lower solute concentration (higher free water concentration) to that of higher solute concentration (lower free water concentration) until the solute concentrations on both sides of the membrane are equal. The diffusion of free water across a selectively permeable membrane, whether artificial or cellular, is called osmosis. The movement of water across cell membranes and the balance of water between the cell and its environment are crucial to organisms. ("Diffusion And Osmosis - Difference And Comparison | Diffen"). A semi-permeable membrane known as the cell membrane surrounds the living cells of both plants and animals. Both solute concentration and membrane permeability are

During osmosis, solvents move across a semipermeable membrane in order to regulate the solute balance within the cell (Campbell Biology). Experiment 5.5 was conducted to further research osmotic activity, particularly in potato cells in different osmolarities of a NaCl solution. The goal of the experiment was to find out whether the potato slices used would be hypotonic or hypertonic to the different osmolarities. This process is relevant because without osmosis, the passage of solvents would not be possible. To perform the experiment, seven potato slices were soaked in 5cm of a different osmolarity level of a NaCl solution (0M – 0.6M) to determine whether each slice was hypotonic or hypertonic to the NaCl solution it was placed in, based on percent weight change. The prediction that the potato slices soaked in solutions with lesser osmolarities (0M – 0.1M) of NaCl would be hypotonic to their solutions, and the potato slices soaked in solutions with higher osmolarities (0.2M – 0.6M) would be hypertonic to their solutions was supported by this experiment because the slices soaked in (0.2M – 0.6M) had

The following hypothesis was made in regard to effect of the concentration gradient on the rate of diffusion: The higher the concentration gradient, the faster the rate of diffusion.

Osmosis is defined as the tendency of water to flow through a semipermeable membrane to the side with a lower solute concentration. Water potential can be explained by solutes in a solution. The more positive a number is more likely it will lose water. Therefore should water potential be negative the cell the less likely it will lose water. In using potatoes the effects of the molarity of sucrose on the turgidity of plant cells. According to Clemson University, the average molarity of a White potato is between .24 M and .31 M when submerged in a sorbitol solution. This experiment was conducted with the purpose of explaining the relationship found between the mass in plants when put into varying concentrations of sucrose solutions. Should the potatoes be placed in a solution that contains 0.2M or .4M of sucrose solution it will be hypotonic and gain mass or if placed in .6M< it will be hypertonic and lose mass instead. Controlled Variables in this lab were: Composition of plastic cups, Brand of Russet Potatoes, Brand of Sweet Potatoes and the Temperature of the room. For independent variable that caused the results recorded it was the different Sucrose concentrations (0.0M, 0.2M, 0.4M, 0.6M, 0.8M, 1M). The dependent variable was the percentage change from the initial weighs to the final. The cup with .4 molarity was the closest to an isotonic solution and was used as the control group for the lab. Water potential is the free energy per mole of water. It is

If someone was to drown in salt water their would be a dramatic change in the shape of the blood cells found in the body, exspecially when compared to a victim that drowns in fresh water. This is all tied in to the process of osmosis, or the diffusion of water through a selectively permeable membrane. Water moves through the membrane until equilibrium is reached. Initially, the more concentrated solution results in a increase of volume and pressure. Their are three types; isotonic, hypertonic, and hypotonic.

Finally, the potato chunk placed in a solution with 1 molar of sucrose began with a volume of 2.025mm3, and decreased to a volume of 1.078mm3 overnight. This was a decrease in volume by 47%. This potato chunk in this solution began with a mass of 2.1 grams, and decreased to a mass of 1.3 grams, which was a 38% decrease in mass. Although the data presented does not include every data point collected, the main points shown represent how a plant cell will decrease in mass and volume when placed in a higher sucrose solution. This decrease of volume and mass is due to the plant cell being placed into a hypertonic solution.

Osmosis is a special type of diffusion where water molecules move down a concentration gradient across a cell membrane. The solute (dissolved substance) concentration affects the rate of osmosis causing it either to speed the process up or slow it down. Based on this, how does different concentrations of sucrose affect the rate of osmosis? If sucrose concentration increases in the selectivity-permeable baggies, then the rate of osmosis will increase.

Cells in all living things have an outer layer known as the cell membrane. The structure of the cell membrane consists of the phospholipid bilayer organized by the arrangement of hydrophilic heads and hydrophobic tails. It is a selectively permeable membrane, where it divides the outer environment from the interior of the cell. It can control substances moving in and out of living cells. Certain molecules like gases, water, and food are permitted to pass the membrane through the method of diffusion. Diffusion refers to the process in which molecules move on the concentration gradient, where they move from an area of high concentration to an area of low concentration. A type of diffusion is known as osmosis. It is the diffusion of water moving across the selectively permeable membrane. In this lab, students will be using eggs to construct an experiment to get a better study on how osmosis works in a cell. The eggs will be soaked in vinegar solution to remove their shells to expose each inner layer that resembles a selectively permeable membrane. The egg shell is composed of calcium carbonate that would dissolves in acidic solution such as vinegar. In the chemical reaction, it releases carbon dioxide gas. After the removal of the egg shell, it will be ready to be able to construct the experiment.

Osmosis is a special type of diffusion. It is the diffusion of water across a semipermeable membrane which is a membrane that is freely permeable to water but is not freely permeable to solutes, the water moves from a dilute solution to a more concentrated solution (Karp, 2010). Both diffusion and osmosis are passive transport, energy is not used in the transport. In osmosis water moves across a membrane toward the solution of greater concentration, because the concentration of water is lower there (Martini and Bartholomew., 2007).

The way to get the full results of this lab was through the process of osmosis. Osmosis is the movement of water across a membrane into a more concentrated solution to reach an equilibrium. When regarding cells osmosis has three different terms that are used to describe their concentration. The first of these words is isotonic. Cells in an isotonic solution show that the water has no net movement and the amount of water that goes in is the same that goes out. Isotonic comes from the root iso, which means equal. This makes sense because the definition of isotonic is: same concentration. The second out of three words is hypotonic. Cells in a hypotonic

I have been hired to recommend soil salt concentration and soil pH, as well as optimize light bulbs, for a greenhouse growth of different types of potatoes. Based on the recommendations that I give to the growers, they will be able to begin their trails to further optimize potato growth. To be able to find the recommended soil salt concentration and soil pH for these potatoes I had to be able to determine the ideal soil salt concentrations by calculating percent mass change in potatoes at various salt concentrations, determine the optimal pH for maximum catalase activity, and I had to be able to use a spectrophotometer to determine the absorbance of pigment extracted from leaves. Initially,important information to know to be able to determine the ideal soil salt concentrations by calculating percent mass change in potatoes at various salt concentrations is osmosis, osmosis in animals cells vs.plant cells, enzymes, catalase enzymes, and determining the absorption spectrum extracted from leaves.

Data: Effect of Solute Concentration on Osmosis in Potato Cells (for the 6 groups of our class)