Question

how does sap moves upward through the stem against the force of gravity​

Answer 1

The factors responsible for ascent of xylem sap are :

1. Transpiration pull : The Transpiration being carried out in the upper regions of the plant causes a continuous loss of water which causes a negative pressure to develop which drives the water upwards. Water has high tensile strength hence the continuous flow of water is not broken.

2. Root pressure : it is the positive pressure developed in the roots due to absorption of water and minerals from the soil which forces the water upwards to a certain range as well as prevents the formation of air bubbles.

3. Capillary action : It is the ability of water to rise up in thing tubes or columns. Water has the property of cohesion that binds the water molecules together as well as adhesion which helps the water molecules to stay attracted to the xylem walls.

4. Imbibition : It is the phenomenon in which colloidal particles attract a large amount of water. This also adds up in the overall process of ascent of xylem sap.

Hope you understood.

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Answer 2

Answer:

in ascent of sap , the sap moves upward through the stem against the force of gravity because of these five forces which acts:-

1- Root pressure

2- adhesion and cohesion of water

3- capillarity action

4- transpirational pull

5- osmosis

Explanation:

these are the main forces which hepls in the upward movement of sap .

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