Final answer:
Osmosis is the movement of water through a semipermeable membrane, while facilitated transport involves the movement of substances across the membrane with the assistance of transmembrane proteins down a concentration gradient. Both processes are important methods of transport through semipermeable membranes.
Step-by-step explanation:
Osmosis is the movement of water through a semipermeable membrane according to the concentration gradient of water across the membrane, which is inversely proportional to the concentration of solutes. While diffusion transports material across membranes and within cells, osmosis transports only water across a membrane and the membrane limits the diffusion of solutes in the water. One example of osmosis is the movement of water across the membrane of red blood cells and the membranes of kidney tubules. Facilitated transport, on the other hand, involves the movement of substances across the plasma membrane with the assistance of transmembrane proteins down a concentration gradient without the expenditure of cellular energy. These proteins form channels or pores that allow certain substances to pass through the membrane. Both osmosis and facilitated transport are important methods of transport through semipermeable membranes.