Question

Tracheids and vessels of the xylem are dead cells and are capable of carrying water and minerals. The sieve elements of phloem retain their plasma membrane and some internal structures and are considered to be living in order to carry water, sugar and other organic molecules. Why couldn't the phloem function if the cells were dead? Why does phloem cells have to be living for them to function when dead cells allow xylem to function? Explain.

Answer 1

Phloem couldn’t function if the cells were dead because it requires active transport since it is moving sugars across an increasing gradient. And In the absence of downward movement of food the portion of the bark above the ring on the stem becomes swollen after a few weeks.

Phloem cells : from leaves to rest of the plant it conduct food. Phloem cells are usually located outside the xylem. The two most common cells in the phloem are the companion cells and sieve cells & sieve tube elements needs to distribute the photosynthesis assimilates all over the plant, means it needs to move this in all directions , while xylem moves water only in 1 way from roots to leaves, so, it doesnt need to be alive