AP BIOLOGY

Detailed explanation-1: -Xylem transports water, minerals, and nutrients from the soil to all the plant parts. There are two types of “transport” tissues in plants-xylem and phloem. Water and solutes are transported by the xylem from the roots to the leaves, and food is transported from the leaves to the rest of the plant by the phloem.

Detailed explanation-2: -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. Cohesion (water sticking to each other) causes more water molecules to fill the gap in the xylem as the top-most water is pulled toward the stomata.

Detailed explanation-3: -As water evaporates through the leaves, more water is pulled up through the roots of the plant. Nutrients and sugars from photosynthesis are dissolved in water and move from areas of high concentration, like the roots, to areas of lower concentration, such as the blooms, stem and leaves, for growth and reproduction.

Detailed explanation-4: -This is called the cohesion–tension theory of sap ascent. The cohesion-tension theory explains how water moves up through the xylem. Inside the leaf at the cellular level, water on the surface of mesophyll cells saturates the cellulose microfibrils of the primary cell wall.

Detailed explanation-5: -Once in the xylem tissue, water moves easily over long distances in these open tubes (Figure 5). There are two kinds of conducting elements (i.e., transport tubes) found in the xylem: 1) tracheids and 2) vessels (Figure 6).