Section 2
Passive Transport
By Boundless
![Thumbnail](../../../../../../figures.boundless-cdn.com/18622/square/figure-05-02-02.jpeg)
Passive transport, such as diffusion and osmosis, moves materials of small molecular weight across membranes.
![Thumbnail](../../../../../../figures.boundless-cdn.com/18630/square/figure-05-02-01.jpeg)
The hydrophobic and hydrophilic regions of plasma membranes aid the diffusion of some molecules and hinder the diffusion of others.
![Thumbnail](../../../../../../figures.boundless-cdn.com/18631/square/figure-05-02-02.jpeg)
Diffusion is a process of passive transport in which molecules move from an area of higher concentration to one of lower concentration.
![Thumbnail](../../../../../../figures.boundless-cdn.com/18632/square/figure-05-02-04.jpeg)
Facilitated diffusion is a process by which molecules are transported across the plasma membrane with the help of membrane proteins.
![Thumbnail](../../../../../../figures.boundless-cdn.com/18634/square/figure-05-02-06.jpeg)
Osmosis is the movement of water across a membrane from an area of low solute concentration to an area of high solute concentration.
![Thumbnail](../../../../../../figures.boundless-cdn.com/18635/square/figure-05-02-07.jpg)
Tonicity, which is directly related to the osmolarity of a solution, affects osmosis by determining the direction of water flow.
![Thumbnail](../../../../../../figures.boundless-cdn.com/18636/square/figure-05-02-08.jpeg)
Osmoregulation is the process by which living things regulate the effects of osmosis in order to protect cellular integrity.