Which process involves the movement of dissolved particles across a semipermeable membrane from an area of higher concentration to lower concentration?

The movement of dissolved particles across a semipermeable membrane from an area of higher concentration to lower concentration describes the process of diffusion. In diffusion, molecules spontaneously move to even out their concentration in a solution, flowing from regions where they are more concentrated to areas with lower concentration until equilibrium is reached. This process is critical in various biological systems, including cellular functions and hemodialysis.

Osmosis, on the other hand, specifically refers to the movement of water across a semipermeable membrane, not dissolved particles. Ultrafiltration involves the movement of water and solutes under pressure through a filter that retains larger particles, and concentration refers to the amount of a substance in a given volume of solution, not a movement process. Thus, diffusion is the accurate term for the defined movement of dissolved particles across a membrane.