The plasma membrane is a dynamic structure.
Water is usually the solvent, hence the term aqueous solution.
If a cell from a salt water fish is placed in a beaker of fresh water, the cell is said to be hyperosmotic to the water. If a cell from a fresh water fish is placed into a beaker of salt water, the cell is said to be hypoosmotic to the water. Passive form of transport caused by the help of carrier proteins specific for the molecules they transport. The cell must expend its own energy to move the substances. It takes 3 sodium ions out of the cell for every 2 potassium ions it takes into the cell.