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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 of Biology (Single Science)Cell 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.

ProcessDescriptionsSubstances movedEnergy required
Diffusion Substances move from a high to a low concentration down a concentration gradientCarbon dioxide, oxygen, water, food substances, wastes, eg ureaNo
OsmosisWater moves from a high to a low concentration across a partially permeable membrane and down a concentration gradientWaterNo
Active transportSubstances move against a concentration gradientMineral ions into plant roots, glucose from the gut into intestinal cells, from where it moves into the bloodYes
ProcessDiffusion
DescriptionsSubstances move from a high to a low concentration down a concentration gradient
Substances movedCarbon dioxide, oxygen, water, food substances, wastes, eg urea
Energy requiredNo
ProcessOsmosis
DescriptionsWater moves from a high to a low concentration across a partially permeable membrane and down a concentration gradient
Substances movedWater
Energy requiredNo
ProcessActive transport
DescriptionsSubstances move against a concentration gradient
Substances movedMineral ions into plant roots, glucose from the gut into intestinal cells, from where it moves into the blood
Energy requiredYes
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