Final answer:
A semipermeable membrane allows selective movement of solvent molecules, typically water, from a dilute to a concentrated solution through osmosis, a type of passive transport, until solute concentrations equalize or osmotic pressure balances.
Step-by-step explanation:
A semipermeable membrane is a type of barrier that allows only certain types of molecules or solvents, typically small ones, to pass through while preventing the passage of other substances. In the context of osmosis, a semipermeable membrane will enable the movement of solvent, usually water, from an area of low solute concentration to an area of high solute concentration. This movement continues until the solute concentrations on both sides of the membrane are nearly equal or until the osmotic pressure is balanced.
Placing a semipermeable membrane between two solutions of differing concentrations, as described in the example, will lead to osmosis. The water molecules will move from Solution A, which is presumably more dilute, to Solution B, which is more concentrated. This is driven by the concentration gradient and is an example of passive transport. The net transfer indicates that the semipermeable membrane allows for this process until the solutions' osmotic pressures equilibrate. This principle is fundamental to the understanding of cellular processes and the function of cell membranes.