The increased pressure of water inside the vacuole is called Turgor pressure. Then the cell becomes turgid. Plasmolysis is the opposite of turgor. This happens when plant cells may be placed in a less concentrated solution of water, although this is very unlikely to happen in nature. Water passes out of the vacuole, the cytoplasm, the cell membrane and the cell wall and into the solution outside the cell.
The cell membrane is similar to the membrane mentioned above, so the cell would lose water because of osmosis if it were placed in an environment in which water concentration is greater than that of the cell. A solution is isotonic if the concentration of dissolved substances is the same as the concentration inside the cell. Osmosis does not occur in an isotonic solution. A hypotonic solution is a solution in which the concentration of dissolved substances is lower than the concentration inside the cell. If a cell were put in a hypotonic solution, osmosis will cause water to move through the cell membrane into the cell.
Osmosis Investigation Aim To find out what type of things affect the rate of osmosis in plants for example, temperature and time. I will do this using a piece of potato submerged in different amounts of sugar solution and record any changes in mass. Prediction ========== Osmosis is the movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of low concentration. Therefore I predict that the potato in the highest sugar solution will have the lowest water concentration and the weakest sugar solution will have the highest water concentration. This is due to the fact that in high sugar solutions the water leaves the cells due to osmosis making the potato lighter.
If a potato cell was placed in the same circumstances the cells would increase in length, volume and mass because of the osmotic effects. If the same potato cells were placed in a solution with a low water concentration, then the effects would be the opposite - water would move out of the cell into the area of lower concentration, the water. Thus, the potato chip will decrease in length, volume and mass. In more extreme cases, the cell membrane would break away from the cell wall and the cell is then known as plasmolysed. The higher the concentration of water in the external solution, the higher the amount of water that enters the cell by osmosis.
If the concentration of a sugar solution that caused no osmosis to occur was found, then the concentrations of both the sugar solution and the cytoplasm must be equal. This process happens in both plant and animal cells. Plants have a strong cellulose wall surrounding them. So they gain water through the roots by osmosis and move water into the plant cells using osmosis. This is how plants become turgid or stiff, which helps keep them upright.
This means that when the plant cells are placed in a strong sugar solution (where there is more sugar than water.) there will be a decrease in weight and volume. This process is defined as plasmolysis. This is where the cell membrane pulls away from the cell wall, this is because a lot of water has been moved from the cell as the plant cell has the strong concentration of water and the solution has a weak concentration the water will move from the plant top the water. Sometimes the cell will shrivel up completely and it becomes flaccid.
This could be called a weak or dilute solution. In a low concentration of water the amount of sugar is high. This could be called a strong or concentrated solution. When two solutions are divided by a semi-permeable membrane the water will move from the area of high concentration to the area of low concentration, until both sides are equal (have reached equilibrium). [IMAGE] This can be seen in living cells.
Eventually the cell stops taking up water, even though the concentrations inside and outside are not even. This is because the cell wall becomes stretched and prevents any more water entering. The cell is said to be turgid. Cells placed in a concentrated sugar solution lose water by osmosis, as the water potential is higher inside the cell. As there are more water molecules inside the cell, more water molecules leave the cell than enter it.
A solution that has a lower solute concentration than is present in cells is said to be a hypotonic or hypo-osmotic solution. In this case, excess water flows into the cells and the cells swell. These cells may eventually rupture or burst open. This process is called lysis. Although we simplify osmolarity problems by using the % of a solute to
Osmosis The cell membrane is partially permeable in that it allows some molecules to diffuse rapidly but slows the passing of others. The glucose molecules try to diffuse to the outside but cannot get through the membrane because the pores are too small. The water molecules diffuse trough the pores down the concentration gradient. This membrane- controlled diffusion of water molecuse is controlled by osmosis, it can works both ways so that it can pass into and out of the cell. Osmosis and Diffusion If water is withheld from a flowering plant, the flowers wilt.