How do things move across the cell membrane, either in or out? This animation shows two broad categories of how things pass into or out of a cell: passive transport and active transport.

Passive transport is automatic; no input of energy is required. For example, diffusion is a passive process in which particles move either into or out of the cell from an area of higher concentration to an area of lower concentration.

Active transport, on the other hand, is when particles move from an area of lower concentration to an area of higher concentration. Because particles are moving against the concentration gradient, energy is required.

After viewing this video, the viewer will be able to:
• List the two broad categories of cell transport
• Describe the difference between active and passive transport.

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