Page 18 - E-Biology Sec.2 2024-2025 U1_Handy

2- Ascent of water and salts from the soil:

Root hairs absorb water by osmosis.
It moves to the root tissues by osmotic pressure.
Xylem vessels and tracheids
Xylem of the stem then to the vessels of the leaves (veins)
Mesophyll tissue (decreasing of the cell sap concentration)
Water evaporates from the mesophyll cell walls to air chambers.

(increasing the concentration of the cell sap and increase their ability to
pull up water)

• Adhesion & cohesion theory explains the role of transpiration in water
ascent in the vessels of tree till 125 m.

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Second Term