Question

How does surface area affect osmosis? How does the water potential affect osmosis?

Answer 1

When the two solutions having different osmotic concentrations are separated by means of a semipermeable membrane the molecules of water move from the region of high chemical potential to a region of its lower chemical potential. This movement of water is called osmosis.

Complete answer:
Basically the osmosis was the diffusion of solvent across a semipermeable membrane. Pure water has maximum free energy, diffusion pressure, and chemical potential. When some soluble substances dissolve into it the free energy of its water molecules decreases. Likewise the diffusion pressure and chemical potential also decrease. Therefore the free energy, diffusion pressure, and chemical potential of solvent molecules in a solution are always less than those of pure solvent. Show the water molecules move from the region of more diffusion pressure, potential, and free energy to the region of less diffusion pressure, potential, and free energy.
The free energy per mole of any substance is called the chemical potential of the chemical system. The water potential is thus the potential energy of water. It decides the direction in which water will move from one cell to another cell in two regions. Water potential, thus helps in determining the direction in which the water molecules can move by osmosis.
The increase in the surface area to volume ratio of a cell is directly proportional to the rate of osmosis, that is it increases the rate of osmosis.

Note: When the water molecules move out of the cell due to hypertonic solution the type of osmosis is termed exosmosis. And water molecules enter the cell to two hypotonic solutions the process is called an endosmosis.