AP BIOLOGY

Detailed explanation-1: -Xylem vessels always push water upwards and nutrients towards roots. Tracheids are dead tubular cells with tapering ends, vessels with thin elongated structures that have a tubular appearance, and no cytoplasm.

Detailed explanation-2: -Tracheids, vessels and xylem fibres are dead when mature.

Detailed explanation-3: -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.