Tonicity refers to the affect of a solution on a cell. A solution is a mixture of two or more substances in which one (a solute) is dissolved in the other (a solvent). So a solute is the substance that is dissolved in a solvent to form a solution. This solution is homogeneous, meaning that it is a single phase and none of the solute is visible in the solvent. Common solutes would be salt or sugar. A common solvent would be water.
That solute can exert a certain amount of pressure referred to as tonicity. This pressure can affect the fluid volume and the pressure in a cell by affecting the movement of water down its concentration gradient. Yes, water, as other molecules will move down it’s concentration gradient.
Tonicity has three classifications; hypertonicity, hypotonicity and isotonicity. These refer to the concentration of a solution in reference to a living cell (a membrane bound structure).
Hypotonic –refers to a solution that is lower in solutes than that of the fluid inside of a cell. As a result, water will flow across the cell membrane into that cell (down its concentration gradient) from the surrounding environment eventually causing the cell to swell and burst (c).
Hypertonic – refers to a solution that is higher in solutes than that inside of a cell. As a result, water will flow out of the cell into the surrounding fluid eventually causing the cell to shrink or crenate (d).
Isotonic – refers to a solution whose concentration of solutes is equal to the concentration of solutes inside of a cell. The water flows equally across the membrane in both directions causing no change in the volume or shape of the cell (a,b).
Answer:
Tonicity of a solution is an important concept which plays a major role in maintaining the balance in the cells. One example is the living of organisms in fresh water these fresh water organisms have certain vacuoles that help in maintaining their tonicity otherwise the organisms are going to burst and die.
Tonicity is the defined as a process that describes the maintaining the concentration gradient across the semi permeable membrane. The tonicity is described in using 3 ideal terminologies ''isotopic'', ''hypotonic'' and ''hypertonic'' solutions.
