A comparison table of diffusion, osmosis and active transport characteristics Doc Brown's GCSE biology exam revision study notes

Transport: 8. A comparison table of diffusion, osmosis and active transport characteristics

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INDEX of biology notes on transport in organisms

(8) A comparison table of diffusion, osmosis and active transport characteristics

Mode of transfer	Substances being moved	Situation conditions	Requirements	Energy required?
Diffusion	Any soluble substance - dissolved gas, liquid or solid	From a higher to a lower concentration	Transfer of substances down a concentration gradient	No energy needed
Osmosis	Water	From a dilute solution to a more concentrated solution	Water passing through a partially permeable membrane	No energy needed
Active transport	Any dissolved substance	Transferring a substance from a lower concentration to a higher concentration	Moving substances against a natural diffusion concentration gradient through a partially permeable membrane	Uses protein carrier molecules and energy needed from ATP - respiration in the mitochondria

Phrasing: In the context of diffusion - from a higher to a lower concentration means transfer from ...

(i) a more concentrated solution to a more dilute solution,

or (ii) a higher/greater level/concentration of a gas to a lower/smaller level/concentration

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