active and passive transport

Active transport is the movement of particles across a cell membrane from an area of lower concentration to an area of higher concentration, requiring energy.

Passive transport is the movement of particles across a cell membrane without the use of energy, typically 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 equilibrium is reached.

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.

Exocytosis is the process by which a cell expels materials in vesicles that fuse with the cell membrane, releasing their contents outside the cell.

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

Protein pumps are specialized proteins in the cell membrane that use energy to move ions or molecules against their concentration gradient.

Facilitated diffusion is a type of passive transport that uses transport proteins to help move molecules across the cell membrane.

The cell membrane is a protective barrier that surrounds the cell, controlling what enters and exits the cell.

Cells need energy for active transport to move substances against their concentration gradient, which is not possible through passive means.