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Question
Cohesion and adhesion theory, is otherwise called
Cohesion and adhesion theory, is otherwise called
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Solution
The correct option is A Transpiration pull theory
Upward conduction of water in the form of the dilute solution of mineral ions (sap) from roots to aerial parts is called ascent of sap. It occurs through the tracheary element of xylem. Many theories were put forward to explain the mechanism of ascent of sap but most accepted theory is cohesion and adhesion theory. It is also known as transpiration pull theory. It was proposed by Dixon and Joly. This theory is based on the following assumptions:-1. There is a continuous water column from root hairs to the tip of the plant.
2. Cohesive and adhesive properties of water molecules- Cohesion is the mutual attraction between water molecules. Attraction of water molecules to polar surfaces (such as the surface of tracheary elements is known as adhesion.
3. The process of photosynthesis requires water. Transpiration supplies water for photosynthesis. All the transpiring leaves exert strong transpiration pull on the stem.
Upward conduction of water in the form of the dilute solution of mineral ions (sap) from roots to aerial parts is called ascent of sap. It occurs through the tracheary element of xylem. Many theories were put forward to explain the mechanism of ascent of sap but most accepted theory is cohesion and adhesion theory. It is also known as transpiration pull theory. It was proposed by Dixon and Joly. This theory is based on the following assumptions:-
1. There is a continuous water column from root hairs to the tip of the plant.
2. Cohesive and adhesive properties of water molecules- Cohesion is the mutual attraction between water molecules. Attraction of water molecules to polar surfaces (such as the surface of tracheary elements is known as adhesion.
3. The process of photosynthesis requires water. Transpiration supplies water for photosynthesis. All the transpiring leaves exert strong transpiration pull on the stem.
2. Cohesive and adhesive properties of water molecules- Cohesion is the mutual attraction between water molecules. Attraction of water molecules to polar surfaces (such as the surface of tracheary elements is known as adhesion.
3. The process of photosynthesis requires water. Transpiration supplies water for photosynthesis. All the transpiring leaves exert strong transpiration pull on the stem.
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