Question:
Discuss the factors responsible for ascent of xylem sap in plants.
Solution:
Transpirational pull is responsible for the ascent of water in the xylem. This ascent of water is dependent on the following physical factors:
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Cohesion – Mutual attraction between water molecules
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Surface tension – Responsible for the greater attraction between water molecules in liquid phase than in gaseous phase
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Adhesion – Attraction of water molecules to polar surfaces
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Capillarity –Ability of water to rise in thin tubes
These physical properties of water allow it to move against gravity in the xylem.