Diffusion describes movement from higher to lower concentration without energy.

Diffusion describes movement from higher to lower concentration without energy.

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

Answer: (A)

Movement from a region of higher concentration to one of lower concentration without using cellular energy is diffusion. This happens because molecules are in constant random motion; when there’s more of a substance on one side, collisions push them into the less concentrated area, creating a net flow down the concentration gradient until even distribution is reached. It’s a passive process, so it does not require ATP or other energy. Endocytosis and active transport, by contrast, rely on energy and involve vesicles or carrier proteins moving substances, often against their gradient. Osmosis is a special case of diffusion focused on water crossing a semipermeable membrane; the situation described fits the general, broad idea of diffusion best.

Movement from a region of higher concentration to one of lower concentration without using cellular energy is diffusion. This happens because molecules are in constant random motion; when there’s more of a substance on one side, collisions push them into the less concentrated area, creating a net flow down the concentration gradient until even distribution is reached. It’s a passive process, so it does not require ATP or other energy. Endocytosis and active transport, by contrast, rely on energy and involve vesicles or carrier proteins moving substances, often against their gradient. Osmosis is a special case of diffusion focused on water crossing a semipermeable membrane; the situation described fits the general, broad idea of diffusion best.