Which process is the net movement of molecules from a region of higher concentration to a region of lower concentration due to their random movement?

Which process is the net movement of molecules from a region of higher concentration to a region of lower concentration due to their random movement?

• A. Osmosis
• B. Diffusion
• C. Ingestion
• D. Reproduction

Answer: (B)

Diffusion is the net movement of molecules from regions of higher concentration to regions of lower concentration, caused by their random motion. Because particles are constantly bouncing about, they spread from crowded areas into less crowded ones until they are evenly distributed. This is a passive process and doesn’t require energy. Think of perfume spreading through a room or dye dispersing in water—mastering the idea that substances tend to even out their distribution by random motion matches what diffusion explains. Osmosis is a specific type of diffusion involving water moving across a semipermeable membrane, so it isn’t about all molecules moving down a concentration gradient. Ingestion and reproduction aren’t about the movement of molecules down a gradient, either.

Diffusion is the net movement of molecules from regions of higher concentration to regions of lower concentration, caused by their random motion. Because particles are constantly bouncing about, they spread from crowded areas into less crowded ones until they are evenly distributed. This is a passive process and doesn’t require energy. Think of perfume spreading through a room or dye dispersing in water—mastering the idea that substances tend to even out their distribution by random motion matches what diffusion explains.

Osmosis is a specific type of diffusion involving water moving across a semipermeable membrane, so it isn’t about all molecules moving down a concentration gradient. Ingestion and reproduction aren’t about the movement of molecules down a gradient, either.