The effects of hypertonic NaCl. When red blood cells are placed in a hypertonic solution, the higher effective osmotic pressure of the bathing solution compared with the intracellular fluid results in water moving down its osmotic gradient and a net movement of water out of the cell via osmosis (10).

– When a cell is put in a hypertonic solution, the water leaves the cell and the cell shrinks.

Pure water is a hypotonic solution compared to red blood cells, hence if placed in it the cell will swell. When red blood cells are in a hypertonic solution, i.e. higher concentration solution, water moves out of the cell faster than it comes in. This results in shrinking (shriveling) of the blood cell.

Plasmolysis is the shrinking of the cytoplasm of a plant cell in response to diffusion of water out of the cell and into a high salt concentration solution. During plasmolysis, the cell membrane pulls away from the cell wall. Plant cells maintain their normal size and shape in a low salt concentration solution.

The distilled water outside the red blood cell, since it is 100% water and no salt, is hypotonic (it contains less salt than the red blood cell) to the red blood cell. The red blood cell will gain water, swell ad then burst. The bursting of the red blood cell is called hemolysis.

Approximately 98 percent of water taken up by the roots is lost through transpiration in most plant species. Transpiration, and resulting water loss, is unavoidable as the leaves’ stomata need to be open to let in carbon dioxide for photosynthesis. When air humidity is low, transpiration increases.

No osmosis occurs. Plant cells placed in a solution with a high water concentration compared to their contents (eg pure water) will gain water by osmosis and swell up until their cytoplasm and cell membrane are pushing against their cell wall. The presence of the plant cell wall prevents plant cells from bursting.

When a plant cell is placed in pure water, it takes up water molecules by osmosis because the water potential of the cell is lower than that of the water surrounding it. However, it does not absorb water until it bursts because it has a strong cellulose cell wall.

It will make the cell to shrink. Hence, animal and plant cell will shrink if placed in a solution of sugar or salt in water due to osmosis.

Imbibition is a special type of diffusion that takes place when water is absorbed by solids-colloids causing an increase in volume. Examples include the absorption of water by seeds and dry wood. Water surface potential movement takes place along a concentration gradient; some dry materials absorb water.

You can consider osmosis to be a special case of diffusion in which diffusion occurs across a semipermeable membrane and only the water or other solvent moves. Diffusion and osmosis are both passive transport processes that act to equalize the concentration of a solution.

Diffusion is the movement of molecules from an area of high concentration of the molecules to an area with a lower concentration. The difference in the concentrations of the molecules in the two areas is called the concentration gradient. The kinetic energy of the molecules results in random motion, causing diffusion.

Diffusion can also happen in liquids. This is because the particles in liquids can move around each other, which means that eventually they are evenly mixed. For example, potassium manganate(VII) is a purple solid. If you put a crystal of it into a jar of water, the purple colour spreads slowly through the water.

This is because in hot water, the water molecules have more energy and are moving faster than the molecules of cold water. Because diffusion happens from high concentration to low concentration, the more molecules are moving, the more opportunities they have to mix together.

It is caused by the random movement of the particles. Diffusion is very important in the body for the movement of substances eg the movement of oxygen from the air into the blood and carbon dioxide out of the blood into the air in the lungs, or the movement of glucose from the blood to the cells.

The greater the difference in concentration, the quicker the rate of diffusion. The higher the temperature, the more kinetic energy the particles will have, so they will move and mix more quickly. The greater the surface area, the faster the rate of diffusion.

When a cell’s surface area increases, the amount of substances diffusing into the cell increases. This is known as the surface area/volume ratio (SA/V ratio). A cell will eventually become so large there is not enough surface area to allow the diffusion of sufficient substances like oxygen and it will die.

concentration difference (concentration gradient) – diffusion is faster if there is a big difference in the concentration between the area the substance travels from and the area that it is moving to.