Transport in plantsHard
Question
The rupture and fractionation do not usually occur in the water column in vessel/tracheids during the ascent of sap because of
Options
A.lignifiend thick ealls
B.cohesion and adhesion
C.weak gravitational pull
D.transpiration pull
Solution
Thevertica conduction of eater from root to aerial parts of plant is called ascent of sap. The water molecules remain joined to each other due to a force of attraction called cohesion force. This attraction is due to the presence of hydrogen bonds between them. The magnitude of this force is very highthrefore,the continuous water column in the ylem cannot be brokeneasily due ti the force of gravity of other odstructions offered by internal tissues in the upward movement of water. This adhesive property of wter ie, attraction between the water molrcules and the walls of xylem ensures the continuity of water column in xylem.
Due to transpiration water evaporates to outer atmosphere through stomata. As a result leaf cells develop low water potential and water from leaf veins moves into leaf cells. The xylem vessel in tuen draw water from xylem of main stem. A pressure (pull) is thus, exerted by all the leaves on the stems, which is called transpiration pull. This is strong enough to pull up the column of water to a great height.
Due to transpiration water evaporates to outer atmosphere through stomata. As a result leaf cells develop low water potential and water from leaf veins moves into leaf cells. The xylem vessel in tuen draw water from xylem of main stem. A pressure (pull) is thus, exerted by all the leaves on the stems, which is called transpiration pull. This is strong enough to pull up the column of water to a great height.
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