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Monday, October 22, 2012

5. Excess amount of absorbed water by plants is liberated out by :


(A) Evaporation
(B) Osmosis
(C) Diffusion
(D) Transpiration

Ans. (D) Transpiration

Evaporation is the process in which water is changed from its liquid state into its gaseous state called water vapor.

Osmosis is the tendency of water to flow from a hypotonic solution (low concentration of dissolved substances) to hypertonic solution (higher concentration of dissolved substances) across a semipermeable membrane.

Diffusion is the passive movement of molecules or particles along a concentration gradient, or from regions of higher to regions of lower concentration.

Transpiration is the process of loss of water from plants through stomata which are small openings on the underside of leaves connected to vascular plant tissues.

Difference between Evaporation and Transpiration :
Evaporation takes place only on the surface of water which is different from liberation of water from plants i.e. Transpiration.

Evapotranspiration is the sum of both evaporation and transpiration - the way water moves from the liquid state to the gaseous state

Visit this link for watching flash study content on Transpiration :
http://www.sciencemag.org/site/feature/misc/webfeat/vis2005/show/transpiration.swf

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