If a cell were put in a hypotonic solution, osmosis will cause water to move through the cell membrane into the cell. A solution is hypertonic if its concentration of dissolved substances is greater than the concentration inside the cell. If a cell were placed in a hypertonic solution, it would lose water. All particles that pass through the plasma membrane by the process of diffusion do not require energy, so their movement is called passive transport. The transport of materials against a concentration gradient requires energy, so it is called active transport.
If a plant cell is placed in pure water, water outside the cell will flow into the cell by osmosis as the interior of the cell has a lower water potential than the pure water. The reason why the interior has a lower water potential is because the cytoplasm has substance like glucose dissolved into it. As more and more water flows into the cell the cell becomes more and more rigid. Eventually the cell becomes turgid and this is when the cell will not accept anymore water as the water potential inside and outside now balanced. If we replicated this with an animal cell it would burst as water would enter osmotically and then the cell would become rigid and there would be no support from a cell wall, and thus the cell will burst.
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.
In concentrated solutions, water is sucked out of the cell by osmosis and the cell shrinks. Both could be fatal if allowed to carry on in the body. This does not happen though because the blood water levels are kept constant by the process of homeostasis. The kidneys are the main regulator of the amount of water in the blood as well as
For example, if a plant cell (like the potato tuber cells) is in equilibrium with an external solution of such a concentration that there is no net gain or loss of water then the water potential of the external solution will be equal to the water potential of the cell. (Roberts 1991) By convention, the water potential of pure water is set at zero. Knowing that solutes make the water potential of solutions lower, solutes make solutions negative. Solute potential is the amount that the solutes lower the water potential of a solution. Pressure potential is especially important in plant 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.
If the medium has exactly the same water concentration as the cell, there is no overall movement. The cell will stay the same size. Water will cross the cell membrane in both directions, but the amount entering it will be the same amount leaving it, so there is no overall movement of water. The cell will stay the same size. If the medium has a lower concentration of water than the cell, the cell will lose water by osmosis.
The living contents of the cell contracts and eventually pulls away from the cell wall and shrinks, this is known as plasmolysis. If you put a plant cell in water, water enters by Osmosis, and then swells up. However, the cell will not burst. This is due to the fact that the cell walls are made from cellulose, which is extremely strong. Eventually, the cell stops swelling, and when this point is reached, we say the cell is turgid.
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.
The water passes through what is known as a partially permeable membrane, which basically is what separates living cells from their surrounding. The membrane is called partially permeable and not fully permeable because it only allows water to diffuse through it and not solute. The cell wall is an example of a fully permeable membrane because it allows water and solute to pass through it, it does not block any of these molecules. The diffusion of water molecules by osmosis always flows down a water potential gradient, which basically means from a high to a low water potential this is how the water moves up through a plant in the xylem vessels, once one cell is full of water, the water will move all at once to the next cell. The water is moving from a place of high concentration to a place of low concentration, like the valves in our hearts stop our blood flowing back the other way, the cell membrane of the cell make sure the water only flows up the plant, this is known as the transpiration stream.