Active vs Passive Water Absorption

Difference between Active and Passive Absorption of Water in Plants: Plants absorb water along with minerals from the soil through root by a process called ‘absorption of water’. Based on the involvement of metabolic energy, the water absorption process in plants may be of two types – (1) Active absorption and (2) Passive absorption.

Active absorption: It is the absorption of water, usually against the concentration gradient, by the utilization of metabolic energy (energy from ATP).

Passive absorption: Absorption of water without the utilization of metabolic energy.

The present post discusses the Difference between Active and Passive water absorption process in plants with a comparison table.

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Active and Passive Absorption of Water in Plants

Sl. No.	Active Absorption	Passive Absorption
1	Active absorption of water utilizes metabolic energy	Passive absorption utilizes solar energy
2	Water is absorbed ‘by’ the roots (Roots have an active role)	Water is absorbed ‘through’ the roots (Roots have only a passive role)
3	The water is absorbed by osmosis and non-osmosis method along or against the DPD gradient	Water is absorbed as a result of the tension created by the transpiration pull
4	Involves symplast * (protoplast) movement of water	It involves apoplast * (nonliving part) movement through free spaces
5	Absorption is independent of transpiration	Absorption is dependent on transpiration
6	Usually, takes place when the water level is high in the soil	Usually, takes place when the water level is low in the soil
7	Occur only in the presence of roots	Occurs even in the absence of roots
8	Produce positive pressure in the xylem canals	Produce negative pressure in the xylem canals
9	Absorption rate is comparatively slow	Absorption rate is comparatively fast
10	Quickly inhibited by metabolic inhibitors or toxins	Metabolic inhibitors or toxins do not have an immediate effect on passive absorption
11	Two types: (1) Active osmotic water absorption and (2) Active non-osmotic water absorption	No such classification in passive water absorption

* Symplast: a living portion formed by the continuous network of interconnected plant cell protoplasts

*Apoplast: a continuous network of channels formed by the dead portions of the cell such as cell wall and intercellular spaces.

*Osmosis: movement of molecules of a solvent in a solution from a region of higher concentration to a region of lower concentration through a semipermeable membrane (example: plasma membrane).

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