AP BIOLOGY

Detailed explanation-1: -The sieve elements are elongated and narrow cells that are connected together to form the phloem’s sieve tube structure. They are considered the highly specialized types of cells that are found in plants.

Detailed explanation-2: -The structural elements of phloem include sieve tubes, companion cells, phloem parenchyma and secretory cells. The sieve tube is the conducting element of the phloem. It is formed from a vertical series of elongated cells, interconnected by perforations in their walls in areas known as sieve plates.

Detailed explanation-3: -Sieve cells and sieve tubes are known as sieve elements.

Detailed explanation-4: -Sieve tubes, which are columns of sieve tube cells having perforated sievelike areas in their lateral or end walls, provide the main channels in which food substances travel throughout a vascular plant.

Detailed explanation-5: -Sieve tubes and companion cells are components of xylem tissue.