In animals, plants and microorganisms, substances move into and out of cells by diffusion, osmosis and active transport.
Process | Description | Substances transported | Energy required |
---|---|---|---|
Diffusion | Substances move from a high to a lower concentration down a concentration gradient | Carbon dioxide, oxygen, water, food substances, wastes, eg urea | No |
Osmosis | Water moves from a high to a lower concentration across a partially permeable membrane and down a concentration gradient | Water | No |
Active transport | Substances more from low to higher concentration up a concentration gradient | Mineral ions into plant roots. Glucose from the gut into intestinal cells, from where it moves into the blood | Yes |