Movement in and out of cells
In a gas or liquid particles move
from an area of high concentration to an area of low concentration until
the particles are uniformly spread out.
We say that the particles move down a concentration
gradient. They are moving from a region where their
concentration is high to a region where their concentration is low.
This is a random process and does not need to be provided with energy.
Particles in a gas or liquid are always moving about at random and will,
over time spread themselves evenly (randomly) throughout the gas or