how does transpiration help in upward transportation of substance
Answers
Answer:By root pressure.
Answer:
Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. Transpiration is essentially evaporation of water from plant leaves.
The transpiration pull and cohesion tension theory explains the upward movement of water in tall trees. According to this theory, the main force responsible for the upward movement of water is transpiration pull generated in the leaves which pulls the water column filled in the xylem tracheids and vessels.
Explanation:
Transpiration : Constant water loss via transpiration from the leaves causes a negative water pressure in the leaves. The negative pressure in the leaves works like a 'suction' force, pulling the water up the stem.
Capillary Action: water moves up the stem in response to the 'suction' caused by transpiration because of two forces: adhesion and cohesion. Cohesion is the tendency for water molecules to stick together and adhesion is the tendency for water molecules to stick to other surfaces, such as the inside of the xylem vessels. Stem xylem is structurally adapted to take advantage of capillarity, because they are very long with a narrow diameter.
Root Pressure: water can also be moved up the stem via a 'push' force from the roots. Water is constantly being absorbed by the roots due to the negative water potential in the root cells. This movement of water into the roots can cause the water pressure inside the roots to become high, resulting in a force that 'pushes' water up the stem xylem.