AP BIOLOGY

Detailed explanation-1: -Xylem is a tissue consisting of dead, hollowed-out cells that form a system of pipes. The walls of xylem cells are lignified (strengthened with a substance called lignin ). This allows the xylem to withstand pressure changes as water moves through the plant.

Detailed explanation-2: -Xylem consists of tracheids, vessels, parenchyma, and fibers. Vessels consist of vessel elements joined together in files by large perforation plates, large gaps in the end walls between successive vessel elements, while tracheids have tapering ends that overlap with adjacent cells, and lack perforation plates.

Detailed explanation-3: -Xylem-type vessel cells can be either alive or dead. According to researchers and botanists, the elements of xylem tissue are dead except for the living parenchyma. The location of the xylem vessels is present in the vascular bundle carved into the plant and the xylem movement is unidirectional.

Detailed explanation-4: -Tracheids and vessels are the main water-conducting components of the xylem. They are dead cells as they do contain any protoplasm. They are elongated tube-like structures having a lignified wall.