AP BIOLOGY

Detailed explanation-1: -After traveling from the roots to stems through the xylem, water enters leaves via petiole (i.e., the leaf stalk) xylem that branches off from that in the stem.

Detailed explanation-2: -Once water is in the xylem, it travels upwards-against the force of gravity-towards the rest of the plant. Water is able to move against gravity due to two forces: tension and cohesion. Tension is a ‘sucking force’ which is created when water evaporates from leaves (transpiration), pulling more water into the leaf.

Detailed explanation-3: -Plant stems have some very special cells called xylem. These cells form long thin tubes that run from the roots up the stems to the leaves. Their job is to carry water upward from the roots to every part of a plant.

Detailed explanation-4: -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.