What is the difference between passive and active transport.

Passive and active transport are two mechanisms by which substances move across cell membranes. Here's a brief explanation of their differences:

Passive Transport

• Definition: Movement of molecules across the cell membrane without the use of energy by the cell.
• Direction: Moves substances from an area of higher concentration to an area of lower concentration (down the concentration gradient).
• Energy Requirement: Does not require cellular energy (ATP).
• Examples: Diffusion, osmosis, and facilitated diffusion.

Active Transport

• Definition: Movement of molecules across the cell membrane using energy.
• Direction: Moves substances from an area of lower concentration to an area of higher concentration (against the concentration gradient).
• Energy Requirement: Requires energy, usually in the form of ATP.
• Examples: Sodium-potassium pump, endocytosis, and exocytosis.

Final Answer

The main difference between passive and active transport is that passive transport does not require energy and moves substances down their concentration gradient, while active transport requires energy to move substances against their concentration gradient.