Q.
Transpiration and root pressure cause water to rise in plants by
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AIPMTAIPMT 2015Transport in Plants
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Solution:
The transpiration process, pulls wqter upwards with the help ofcohesion and adhesion properties of water molecules. According to transpiration pull theory, due to transpiration, the water column inside the plant comes under tension. This is called 'transpiration puli'. On account of this tension, the water column is pulled up passively from below to top of the plant (almost like a rope). Root pressure is the pressure that forces water, absorbed from the soil, to move through the roots and up i.e., pushes it up) the stem of a plant. It may be due to both the osmosis of water from the soil into the root cells, and the active pumping of salts into xylem tissue which maintains a concentration gradient along which the water moves.