Osmosis
Osmosis is a specific kind of diffusion - it is the diffusion of water molecules. Just like in normal diffusion, water goes from an area of higher concentration to an area of lower concentration. Water can directly diffuse across the cell membrane. No energy is consumed in osmosis, so it is considered passive, but heat energy may speed up the process.
Let's see what osmosis can do. When a cell is placed in an isotonic environment, because the concentration of water inside and outside the cell are equal, there is no net movement of water. Therefore the cell remains the same.
But what if the cell is placed in an environment with a higher or lower concentration? If the environment is hypertonic, then there is a greater concentration of solute outside, so that means a lesser concentration of water there. As a consequence, water leaves the cell and causes it to shrink. this is known as crenation. On the other hand, if the environment is hypotonic, then there is a lesser concentration of solute outside, so the concentration of water there is greater. In this case, water diffuses into the cell and causes the cell to swell or even burst. When plant cells swell, they create turgor pressure on the cell wall. When plant cells shrink, it is known as plasmolysis. The contents inside the cell membrane lose volume, but the cell wall remains the same.
Let's see what osmosis can do. When a cell is placed in an isotonic environment, because the concentration of water inside and outside the cell are equal, there is no net movement of water. Therefore the cell remains the same.
But what if the cell is placed in an environment with a higher or lower concentration? If the environment is hypertonic, then there is a greater concentration of solute outside, so that means a lesser concentration of water there. As a consequence, water leaves the cell and causes it to shrink. this is known as crenation. On the other hand, if the environment is hypotonic, then there is a lesser concentration of solute outside, so the concentration of water there is greater. In this case, water diffuses into the cell and causes the cell to swell or even burst. When plant cells swell, they create turgor pressure on the cell wall. When plant cells shrink, it is known as plasmolysis. The contents inside the cell membrane lose volume, but the cell wall remains the same.