AP BIOLOGY

Detailed explanation-1: -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. The perforations may be restricted to smaller areas, sieve fields, several of which are contained in each sieve plate.

Detailed explanation-2: -Sieve tubes and companion cells are living cells present in the phloem tissue. Phloem is a type of vascular conducting tissue present in plants. Sieve tubes are elongated cells associated with the conduction of food and companion cells remain associated with the sieve tubes. Was this answer helpful?

Detailed explanation-3: -The main conducting elements of the phloem are the sieve elements, of which there are two different types: sieve cells and sieve-tube members. Sieve cells have narrow pores, their sieve areas are quite uniform in structure, and they are distributed evenly on all walls.

Detailed explanation-4: -Sieve tubes, found in angiosperms, are living cells that are associated with companion cells. The association with companion cells helps in distant transportation within the plant cells. The sieve tubes are made up of longitudinal arrangement of sieve tube members from end to end.

Detailed explanation-5: -They are the conduits of food (mostly sugar) transport from the leaves to the rest of the plant. In angiosperms, these cells are known as sieve tubes. In non-angiospermous vascular plants-e.g., gymnosperms, lycophytes, and ferns-rows of sieve cells, showing more primitive structural features, perform the same function.