AP BIOLOGY

Detailed explanation-1: -Tubular shape with no cross walls which allows a continuous column of water + facilitates more rapid transport within the xylem vessels. There are two types-protoxylem (first formed xylem) + metaxylem (mature xylem) depending on pattern of lignin.

Detailed explanation-2: -The xylem is the vascular tissue responsible for the upward conduction of water and nutrients from the roots. The xylem tissue moves water and nutrients to various parts of the plant such as shoots and leaves. Its major components include xylem parenchyma, xylem fibers, tracheids, and xylem vessels.

Detailed explanation-3: -Xylem is a tissue system consisting of specialized cells with lignified secondary cell walls responsible for water movement through the plant. What is lignified? Cells with secondary cell wall thickening typically contain lignin.

Detailed explanation-4: -Both lignin and cellulose are found in the rigid cell walls of the xylem cells (those that conduct water) in the primitive plant Selaginella.