Which process describes the movement of particles from an area of high concentration to an area of lower concentration?

Which process describes the movement of particles from an area of high concentration to an area of lower concentration?

• A. Diffusion
• B. Osmosis
• C. Facilitated Diffusion
• D. Active Transport

Answer: (A)

Movement of particles down a concentration gradient, from high to low, without using energy. This is diffusion, the random motion of molecules that leads to a net flow toward lower concentrations until equilibrium is reached. Osmosis is diffusion of water across a selectively permeable membrane, a specific case focused on water movement. Facilitated diffusion is still diffusion but requires membrane proteins to help substances cross the membrane, though it proceeds down the gradient and without energy. Active transport, on the other hand, moves substances against their gradient and requires energy. So the described process is diffusion.

Movement of particles down a concentration gradient, from high to low, without using energy. This is diffusion, the random motion of molecules that leads to a net flow toward lower concentrations until equilibrium is reached. Osmosis is diffusion of water across a selectively permeable membrane, a specific case focused on water movement. Facilitated diffusion is still diffusion but requires membrane proteins to help substances cross the membrane, though it proceeds down the gradient and without energy. Active transport, on the other hand, moves substances against their gradient and requires energy. So the described process is diffusion.