AP BIOLOGY

Detailed explanation-1: -Phloem is living tissue, responsible for transporting food and other organic materials. Xylem consists of dead cells (parenchyma is the only living cells present in the xylem). Pholem mainly contains living cells (fibres are the only dead cells in the phloem).

Detailed explanation-2: -Hint: In phloem both companion cell and sieve tubes are living cells.

Detailed explanation-3: -Phloem parenchyma and companion cells are elements of phloem and both are living cells. Phloem fibres also called as bast fibres are the only dead cells present in the phloem.

Detailed explanation-4: -The phloem is composed of sieve tubes, companion cells, phloem parenchyma and fibres. The fibres are the dead sclerenchymatous cells in the phloem responsible for mechanical support. These cells are considered as non-living component of phloem.

Detailed explanation-5: -Final answer: Phloem fibre is dead tissue.