Factors Affecting the Movement of Water Through Osmosis

Procedure: Variables: Controlled- water and size of potatoes. Manipulated variables- potatoes growth based on contents of solution.

• I also tried to ensure that each tuber was dried in the same way, but this proved to be very difficult. It was important to only remove the solution from the surface because we did not want to remove any water from the cells which would affect the mass of the tubers.

The graph above indicates that as the concentration of sucrose solution (%) is increased, the percentage change in mass decreases, thus it can be supposed that there is a negative correlation between the sucrose concentrations and the mass of potato cubes. It is also apparent from the graph above that an error has occurred during the 15% sucrose trial as it appears as an outlier also it can be estimated from the graph that approximately10% sucrose solution is the isotonic condition as there is no big change in mass.

An anomaly will be that when the mass of the potato was measured for 6% of sugar solution, the mass at time 5minutes was high then it decreased sharply at times 10 minutes to time 20 minutes this shows that the pressure with which the potato shrunk made the potato less rigid which made the cell membrane of the potato start shrink from the cell itself therefore causing the mass to decrease, also from 20% to 60% of sugar solution was used the mass of the potato decreased sharply as time went on which also shows that the cell membrane of the potato has plasmolysed which shows that the cell membrane has pulled away from the cell which shows with the shrinkage of the potato.

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

8. Use the plastic forceps to remove the potato cylinders from the beakers (keep them together in the same group), and blot off the excess solution weight on them with the paper towels.

Osmosis is the passive movement of water from an area of low solute concentration to an area of high solute concentration, normally across a membrane which prevents the movement of solvent. This is a process by which materials may move into, out of, or within cells. Osmosis doesn’t depend on energy provided by living organisms but is affected by the properties of the cell membrane. The rate of osmosis is dependent on such factors as temperature, pressure, molecular properties such as size and mass, and the concentration gradient. In osmosis, the relationship between a solute’s concentration outside of cell and inside of a cell is described in terms of the tonicity of the solution outside of the cell. A cell is in a hypotonic solution when the solute is more concentrated inside the cell and therefore water moves into the cell. In this solution the cell swells as water enters, this may continue until it ruptures or hemolyzes. In the reverse condition, the cell is in a hypertonic solution

Hypertonic is what the side with a higher concentration of solutes is called. Hypotonic is the side with a lower concentration of solutes. In osmosis the water moves to the hypertonic side from the hypotonic side.

First I gather all my materials needed for the experiment (see materials list). Second I peel and slice potatoes weigh each potato in grams. Get these slices to weigh the same in mass because if they vary to much in mass that could affect the results of the experiment. Third I place each potato in its own beaker. Fourth once the potatoes are placed in beakers I make sure to place enough solution to fully cover the potato. Each beaker should have a different amount of

Small slices of potato are placed in six concentrations of sucrose: 0.0 M, 0.1 M, 0.2 M, 0.3 M, 0.4 M, and 0.5 M. The initial mass of potato is noted before being placed in the solution. The potato remained in the solution for one hour then the potato was removed from the solution and dried off before the final mass was noted. The null hypothesis is that the solutions of different molarities of sucrose will not affect the

If the solution contains only sucrose then the osmotic pressure will increase substantially. This would represent a hypotonic solution because more water molecules are entering the cell meaning the solution contains no invertase. If the osmotic pressure has a slight increase than the solution contains sucrose and invertase due to the rate of the sucrose being broken down, however the cell will overtime begin to shrink. If the osmotic pressure remains close to the same than the solution contains no sucrose, containing only water and invertase. We predicted that because the height of the fluid in the osmometer tubing was increasing only a little bit our blue solution was hypertonic and contained invertase and sucrose. The invertase was able to break down sucrose into glucose and fructose which were small enough to be able to leave the cell membrane. This would reflect a hypertonic solution. We predicted this would cause the cell to shrink in size and the height of the fluid would never increase.

The potato cells, took in, or gave out the water depending on the concentration of the solution it is surrounded in. The results were fine and by looking at the mass measured before the experiment, you can see that there is no reading which seems to be out of the line. As the weights before the experiment range between 2.31g and 2.46g, this tells us that the potato pieces were cut well, and I believe accurate enough. The results show that: - Osmosis actually took place in the experiment.

How do different concentrations of sucrose solutions (0M, 0.2M, 0.4M, 0.6M, 0.8M, 1M) affect the mass of potato cores when in sucrose solution?

This would happen by using similar sizes and lengths of potato cylinders and applying the into different concentrations of sucrose (0,10%,30%, 50%, 70%) in foam cups then measuring the change in mass of the potato cylinders afterwards. Maintaining all variables unchanged such as pH, same size, covered solutions, and a constant temperature. The time taken for all potato cylinders will be 24 hours.

Osmosis is when water passes through a cell membrane, it is also form of a diffusion, which is a form of passive transport. Osmosis will continue to until an equilibrium is reached which is when the solutions are isotonic. This means that the solution has the same amount of solute on both sides. If the solution is hypertonic, it has more solute in the solution. In this situation water will move towards it. if the solution is hypotonic, it has less solute in the solution. Whereas in this situation, water will move out of the solution.