AP BIOLOGY

Detailed explanation-1: -Xylem is unidirectional; its job is to make sure water flows upward. However, phloem is bidirectional and transports food and nutrients to all of the plant. Mature xylem is made up of dead cells that do not have cell contents, while phloem contains living cells (albeit without nuclei).

Detailed explanation-2: -The xylem distributes water and dissolved minerals upward through the plant, from the roots to the leaves. The phloem carries food downward from the leaves to the roots.

Detailed explanation-3: -Abstract. Water flowing through the xylem from the roots to the leaves of most plants must pass through junctions where branches have developed from the main stem. These junctions have been studied as both flow constrictions and components of a hydraulic segmentation mechanism to protect the main axes of the plant.

Detailed explanation-4: -The main function of the xylem vessels is to transport water in one direction, upward from the roots, through the stem, and to the leaves.