Question

Which of the following is not significant in osmosis?
(a)Gravitational potential
(b)Concentration gradient
(c)Solute potential
(d)Pressure potential

Answer 1

Osmosis is defined as the flow of solvent (water) from its high concentration to its low concentration through a semi-permeable or a selectively permeable membrane like the plasma membrane of the living cells.

Complete answer:
Osmosis is a process of diffusion referred specifically to water and it occurs spontaneously in response to a driving force. The net direction as well as the rate of osmosis is determined by the concentration gradient, solute potential, and pressure potential. Water flows in the downhill direction of the concentration gradient from a higher concentration of water to its lower concentration. Similarly, osmosis occurs in the downhill direction of solute potential and pressure potential. When solute potential and pressure potential reach equilibrium, osmosis stops. The gravitational potential does not affect osmosis.

Additional Information: Water potential: Water potential is a measure of kinetic energy possessed by the water molecules. The greater the number of water molecules, the higher is the water potential. Water moves from a container having higher water potential to a container having lower water potential. The unit of water potential is pascals (Pa).
Solute potential: The solute potential is a measure of the concentration of a solution. The higher the concentration of a solution, the more negative is the solute potential of that solution. At atmospheric pressure, water potential equals solute potential. The solute potential is negative of the solute concentration.
Pressure potential: Pressure potential is defined as the positive pressure developed against the cell wall of a cell due to an excess of water present in it. If pressure greater than the atmospheric pressure is applied to a cell, its water potential increases.
So, the correct option is ‘Gravitational potential’.

Note:
-The highest water potential is possessed by pure water and it is denoted by zero.
-The value of water potential is affected by both solute potential as well as pressure potential.
-Gravitational potential is defined as the work per unit mass required to move an object to that location from a reference location.