AP BIOLOGY

Detailed explanation-1: -Xylem tissue is made of millions of tiny tubes made of cellulose. Because water molecules like to stick together (cohesion) and like to stick to the walls of the tubes of cellulose (adhesion), they rise up the tubes all the way from the roots to the leaves.

Detailed explanation-2: -A water drop is composed of water molecules that like to stick together-an example of the property of cohesion. In the picture of pine needles above, the water droplets are stuck to the end of the pine needles-an example of the property of adhesion.

Detailed explanation-3: -Adhesion, which is molecular attraction between “unlike” molecules. In the case of xylem, adhesion occurs between water molecules and the molecules of the xylem cell walls. Cohesion, which is molecular attraction between “like” molecules. In water, cohesion occurs due to hydrogen bonding between water molecules.

Detailed explanation-4: -Cohesion is the term used to describe water molecules sticking to each other. As water molecules travel upwards through the xylem tissue, the molecules cohere to each other. This cohesive attraction creates a chain or column of water molecules. The chain of water molecules is pulled up in a continuous unbroken column.