Question

Which of the following helps in the ascent of sap?
A.Root pressure
B.Transpiration
C.Capillarity
D.All of the above

Answer 1

Hint: Ascent of sap is a part of xylem tissue which is responsible for the upward movement of the water and mineral . It consists of both living and the non living tissue.

Complete step by step answer:
1. The theory of ascent of sap describes the upward flow of the water from the roots of the place to the leaves of the plant through the xylem tissue which is responsible for flow of water within the plants.
2. The theory of ascent of sap describes that the upward movement of water within the plant is due to the transpiration pull , capillarity, cohesive theory and the root pressure.
3. Transpiration is define as the loss of water from the leaves due to excessive sunlight, when sunlight falls on the surface of the leaves water from the leaves get evaporated in atmosphere in the form of vapours it makes a pressure gradient within the plant which pull the water from the root or soil near the plant and results in the upward movement of the water.
4.The theory of capillarity states that when water flows from the Capillarity the water moves away from its high concentration so water moves upward.
5.Roots apply a pressure which results in the flow of water inside the roots from its higher concentration to its lower concentration and that pressure gradient initiates its upward movement.
So all of the above are responsible for the ascent of sap.

 So option D is correct.

Note:
Once the water is absorbed by the root hairs by diffusion it moves deeper into the root layers by two different pathways- apoplast pathway and symplast pathway.