Question

Why is osmotic potential given a negative sign?

Answer 1

Hint: The result of dissolved solutes in cell sap is osmotic potential and is proportional to the concentration of solutes and inversely proportional to the volume of cell water. It is often negative in plants and decreases as solutes accumulate during dehydration of plants.

Complete answer:
The ability of water molecules to pass through a semipermeable membrane from a hypotonic solution (more water, fewer solutes) to a hypertonic solution (less water, more solutes). Because of the presence of solute particles, osmotic potential is the free energy of water in a system. This osmotic potential value is always negative since the presence of solute always produces a solution of less water than the same amount of pure water (means no solute particles are present). Though the osmotic potential is numerically equal to the osmotic pressure.

Water moves to the cell with greater D.P.D.-16 bars from a cell with lower D.P.D. Similarly, osmotic potential is the modern term for osmotic pressure that has the same value but is negative, while positive is O.P. For instance, if the O.P. The atmosphere of the cell is 24; its osmotic potential is -24 bars.

Note: Osmotic pressure is a hydrostatic pressure exerted to the solution to prevent the flow of water through the semipermeable membrane. As a solution will always have some solute, the amount of water will be lesser than pure water. Thus the osmotic potential of a solution will always be negative (value less than zero).