Final answer:
Osmosis is the process where water moves across a semipermeable membrane from an area of high water concentration (and thus low solute concentration) to an area of low water concentration (high solute concentration), facilitated by proteins like aquaporins.
Step-by-step explanation:
Osmosis describes how water moves during the process where it transports only water across a semipermeable membrane according to the water's concentration gradient. This movement is from a region of higher water concentration to a region of lower water concentration, which inherently is from low solute concentration to high solute concentration, inversely proportional to the solutes' concentration. The movement is facilitated by aquaporins in cellular membranes.
In simpler terms, imagine a beaker divided by a semipermeable membrane with unequal concentrations of a solute that cannot move across the membrane. Osmosis will result in water moving from the side with fewer solute particles (higher water potential) to the side with more solute particles (lower water potential), seeking to equalize the concentration on both sides of the membrane.
It's important to note that osmosis is crucial for maintaining homeostasis in cells and is particularly significant in red blood cells and kidney tubules.