Active and Passive Transport

Active transport is the movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration, using energy in the form of ATP.

Passive transport is the movement of molecules across a cell membrane without the use of energy, moving from an area of higher concentration to an area of lower concentration.

Diffusion is the process by which molecules spread from areas of high concentration to areas of low concentration until they are evenly distributed.

Osmosis is the diffusion of water molecules through a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration.

Endocytosis is the process by which a cell takes in materials by engulfing them in a membrane.

Exocytosis is the process by which a cell expels materials by vesicles fusing with the cell membrane.

A hypertonic solution has a higher concentration of solute particles compared to another solution.

A hypotonic solution has a lower concentration of solute particles compared to another solution.

An isotonic solution has the same concentration of solute particles as another solution.

The sodium-potassium pump is a type of active transport that moves sodium ions out of the cell and potassium ions into the cell against their concentration gradients.