is osmosis a type of active transport or a type of diffusion?

Osmosis is a type of diffusion , not active transport.

What osmosis actually is

• Osmosis is the diffusion of water molecules across a partially permeable membrane.
• Water moves from a region of higher water concentration (more dilute solution) to a region of lower water concentration (more concentrated solution), down its concentration gradient.

• Because it moves down a concentration gradient and does not require energy from ATP, osmosis is classified as passive transport, specifically a special case of diffusion.

Why it is not active transport

• Active transport moves substances from low to high concentration, against the concentration gradient.
• This process requires energy from ATP and usually uses carrier proteins or pumps in the membrane.

• Osmosis does not use cellular energy and always goes from higher to lower water concentration, so it does not meet the definition of active transport.

Simple way to remember

• If energy (ATP) is needed and molecules move “uphill” in concentration, think active transport.
• If water is simply spreading out “downhill” through a membrane, think osmosis, a special kind of diffusion.

Information gathered from public forums or data available on the internet and portrayed here.