ICSE Class 9 Answered

Osmotic pressure is the pressure that needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane. Osmotic pressure is of vital importance in biology as the cell's membrane is selective toward many of the solutes found in living organisms. When a cell is placed in a hypertonic solution, water actually flows out of the cell into the surrounding solution thereby causing the cells to shrink and lose its turgidity.