Transport in cells - AQAComparing diffusion, osmosis and active transport

For an organism to function, substances must move into and out of cells. Three processes contribute to this movement - diffusion, osmosis and active transport.

Part ofCombined ScienceCell biology

Comparing diffusion, osmosis and active transport

In animals, plants and microorganisms, substances move into and out of cells by diffusion, osmosis and active transport.

Process	Descriptions	Substances moved	Energy required
Diffusion	Substances move from a high to a low concentration down a concentration gradient	Carbon dioxide, oxygen, water, food substances, wastes, eg urea	No
Osmosis	Water moves from a high to a low concentration across a partially permeable membrane and down a concentration gradient	Water	No
Active transport	Substances move against a concentration gradient	Mineral ions into plant roots, glucose from the gut into intestinal cells, from where it moves into the blood	Yes

Process	Diffusion
Descriptions	Substances move from a high to a low concentration down a concentration gradient
Substances moved	Carbon dioxide, oxygen, water, food substances, wastes, eg urea
Energy required	No

Process	Osmosis
Descriptions	Water moves from a high to a low concentration across a partially permeable membrane and down a concentration gradient
Substances moved	Water
Energy required	No

Process	Active transport
Descriptions	Substances move against a concentration gradient
Substances moved	Mineral ions into plant roots, glucose from the gut into intestinal cells, from where it moves into the blood
Energy required	Yes

Active transport

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