ACTIVE transport of sodium across cell membranes is now established as one of the fundamental physiological processes of most vertebrate cells. This process probably requires some sort of carrier ...

The alternative to active transport is passive transport, which uses kinetic energy only to move the molecules. Passive transport can only move molecules from a region of higher concentration to lower ...

Diffusion Substances move from a high to a low concentration down a concentration gradient Carbon dioxide, oxygen, water, food substances, wastes, eg urea No Osmosis Water moves from a high to a low ...

Diffusion Substances move from a high to a low concentration down a concentration gradient Carbon dioxide, oxygen, water, food substances, wastes, eg urea No Osmosis Water moves from a high to a low ...