LIFE SCIENCE

Detailed explanation-1: -Osmosis is a special type of diffusion, namely the diffusion of water across a semipermeable membrane. Water readily crosses a membrane down its potential gradient from high to low potential (Fig. 19.3 ) [4]. Osmotic pressure is the force required to prevent water movement across the semipermeable membrane.

Detailed explanation-2: -In facilitated diffusion, substances move into or out of cells down their concentration gradient through protein channels in the cell membrane. Simple diffusion and facilitated diffusion are similar in that both involve movement down the concentration gradient.