AP BIOLOGY

Detailed explanation-1: -Sieve tubes are elongated tubular conducting channels of phloem. Each sieve tube is formed of several cells called sieve tube members, sieve tube cells or sieve elements. Sieve tube members are placed end to end. Their end walls have many small pores or sieve pits.

Detailed explanation-2: -Detailed Solution. The correct answer is Phloem transports photosynthetic products. Phloem is a living tissue in vascular plants that conducts the soluble organic compounds synthesized downwards from the leaves during photosynthesis.

Detailed explanation-3: -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-4: -So, the correct answer is ‘Peripheral cytoplasm, a large vacuole and a prominent nucleus; all are absent in a mature sieve tube element’