Comparing Diffusion, Osmosis and Active transport
| Diffusion | Osmosis | Active Transport | |
|---|---|---|---|
| Definition | Diffusion is the spreading out of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration. | Osmosis is the diffusion of water molecules from a dilute solution to a concentrated solution through a partially permeable membrane. | Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). |
| Additional energy needed | No | No | Yes |
| Moves down or against a concentration gradient | Down concentration gradient | Down concentration gradient | Against concentration gradient |
| Moves which substance(s) | Oxygen, Urea, carbon dioxide or glucose | Water only | Glucose, mineral ions, amino acids |
| Membrane needed | Sometimes a membrane is present, but it is not always needed | Yes, partially permeable membrane | Yes with carrier proteins |