Osmosis
Osmosis is a rather simple topic that is nonetheless vitally important to a complete understanding of cellular biology. Osmosis is, in short, the process by which water diffuses through a membrane. When water moves passively through a cell membrane, that's osmosis. However, there are several factors that contribute to the direction of which osmosis occurs. The main constraint on osmosis is concentration. Concentration is the ratio of solute material in a solution to the solvent that it is dissolved in. Concentration can be abbreviated as [salt water], which means literally "Concentration of Salt Water." (Putting brackets around something means the concentration of the thing the brackets are around, if I was unclear before).
Water will naturally move from an area with a lower concentration of solutes to an area with a higher concentration in order to achieve equilibrium, or a state where the concentrations are balanced throughout. Water will move through any membrane it can as long as it is moving to an area with a higher concentration. These areas are called hypertonic, and areas with lower concentrations are called hypotonic.
Osmosis is vital to life because of its function in maintaining equilibrium inside and outside of a cell. However, conditions on a cell can sometimes cause problems. If there is a high concentration of say, salt outside a plant, all the water from inside plant cells will diffuse outside of the plant and cause the plant cells to shrink in a process called plasmoloysis. An example of plasmolysis is the wilting of flowers after they are kept out of water for a time. Because the water content inside the plant goes down, the cells constrict through plasmolysis and the whole plant grows limp, as the cells aren't as tightly packed in the plant and thus can't support the weight of the leaves.
Water will naturally move from an area with a lower concentration of solutes to an area with a higher concentration in order to achieve equilibrium, or a state where the concentrations are balanced throughout. Water will move through any membrane it can as long as it is moving to an area with a higher concentration. These areas are called hypertonic, and areas with lower concentrations are called hypotonic.
Osmosis is vital to life because of its function in maintaining equilibrium inside and outside of a cell. However, conditions on a cell can sometimes cause problems. If there is a high concentration of say, salt outside a plant, all the water from inside plant cells will diffuse outside of the plant and cause the plant cells to shrink in a process called plasmoloysis. An example of plasmolysis is the wilting of flowers after they are kept out of water for a time. Because the water content inside the plant goes down, the cells constrict through plasmolysis and the whole plant grows limp, as the cells aren't as tightly packed in the plant and thus can't support the weight of the leaves.