What is Diffusion? Definition, Meaning & Example
The spontaneous movement of particles from an area of higher concentration to an area of lower concentration.
TL;DR: The spontaneous movement of particles from an area of higher concentration to an area of lower concentration.
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Diffusion: The spontaneous movement of particles from an area of higher concentration to an area of lower concentration.
Explanation
Diffusion is a passive transport process where particles move without requiring energy from the cell. The movement continues until the concentration becomes equal throughout. In living organisms, diffusion is essential for oxygen entering blood cells, nutrients moving into cells, and waste products leaving cells. This fundamental biological process does not depend on the presence of a semipermeable membrane.
Example
When you open a perfume bottle in a room, the fragrance spreads throughout the room as perfume molecules diffuse from high concentration (near the bottle) to low concentration (rest of the room).
Frequently Asked Questions
Is diffusion active or passive transport?
Diffusion is passive transport because it does not require energy; particles move due to their natural kinetic energy.
Can diffusion move particles against concentration gradient?
No, diffusion always moves particles from high to low concentration; it cannot work in the opposite direction without energy input.
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