Question

What is transpiration pull theory ?

Answer 1

Dear student
Transpiration pull or the suction force is the force which aids in drawing the water upward from roots to leaves. In leaves, some amount of water is used for photosynthesis and excess water is released into the atmosphere through openings called as stomata. This results in the upward pull of water from the root to the mesophyll cells by generating a negative pressure in xylem vessels to pull the water from the soil. Transpiration pull in plants results from the evaporation or excretion of water from the surface of cells in the leaves. The loss of water through evaporation from the leaves must be replaced by water coming up the xylem. Water molecules are attracted to each other due to cohesion between them. These forces are strong enough to hold the molecules together in a long column.

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