(a) Osmotic Pressure: The maximum pressure, which is developed in a solution when it is separated from its pure solvent by a semipermeable membrane is called osmotic pressure. The osmotic pressure of a solution is directly proportional to the concentration of solute molecules present in the solvent. The more is number of solute molecules in the solution, the more will be the osmotic pressure of the solution. (b) Wilting: Due to more transpiration or less water absorption by roots, the plants suffer scarcity of water thereby turgor pressure of cells decreases. Due to this the leaves drop down. This situation is called wilting. When leaves wilt at noon and straight at evening, it is called temperory wilting. If the soil lacks water this wilting turns into permanent in this situation plant dies.