NEET BIOLOGY

Detailed explanation-1: -The cohesion – tension theory of sap ascent explains how how water is pulled up from the roots to the top of the plant. Evaporation from mesophyll cells in the leaves produces a negative water potential gradient that causes water and minerals to move upwards from the roots through the xylem.

Detailed explanation-2: -As water molecules evaporate from plant leaves, they attract the water molecules still in the plant, helping to pull water up through the stems from the roots. The combination of transpira-tion and capillary action delivers the water from the bottom to the top of a plant.

Detailed explanation-3: -As transpiration occurs, it deepens the meniscus of water in the leaf, creating negative pressure (also called tension or suction). The tension created by transpiration “pulls” water in the plant xylem, drawing the water upward in much the same way that you draw water upward when you suck on a straw.

Detailed explanation-4: -Water and dissolved minerals are distributed upward through the plant by the xylem, to the leaves which would take place from the roots.

Detailed explanation-5: -The direction of xylem transport is upwards and unidirectional i.e. from roots to other plant parts. The water column moves only upwards because of the two forces, transpirational pull, and positive root pressure.