Passive transport

Definition

Passive transport is the movement of molecules across cell membranes without the need for energy input. It relies on the concentration gradient to facilitate diffusion.

5 Must Know Facts For Your Next Test

1. Passive transport includes processes like simple diffusion, facilitated diffusion, and osmosis.
2. Molecules move from an area of high concentration to an area of low concentration in passive transport.
3. No ATP (adenosine triphosphate) or cellular energy is required for passive transport.
4. Membrane proteins such as channels and carriers can assist in facilitated diffusion, a type of passive transport.
5. Osmosis is a specific kind of passive transport involving the movement of water across a semipermeable membrane.

Review Questions

• What are the main types of passive transport?
• How does passive transport differ from active transport?
• Why is no energy required for passive transport?

Related terms

Simple Diffusion: The movement of molecules directly through the cell membrane without assistance.

Facilitated Diffusion: The process by which molecules pass through a cell membrane using special proteins called channel or carrier proteins.

Osmosis:

The diffusion of water across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration.