Biological Principles, Simplified

 Tonicity Tonicity is the ability of a surrounding solution to cause a cell to gain or lose water.  A hypotonic solution refers to a solution that, when surrounding a cell, causes the cell to gain water.  This is because there is more solute inside the cell than outside the cell. In Greek, 'hypo' means less. Since there are more solutes inside the cell than outside, water will move into  the cell. A hypertonic   solution refers to a solution that, when surrounded a cell, causes the cell to lose water.  This is because there is less solute inside the cell than outside the cell. In Greek, "hyper" means more. Since there are more solutes outside the cell than inside, water will move out of the cell. An isotonic   solution refers to a solution that, when surrounding a cell, doesn't induce any change in the water content of the solution or cell. This is because there are equal amounts of solute inside and outside the cell, so there will be no net movement of wate