Xylem and Phloem

Why do plants need transport systems?

• Because a lot of multicellular organisms like plants hve a high surface area:volume ratio simple diffusion would be too slow a proccess to use to get all the necissary nutrients to relevant parts of the plant.

XYLEM

• transpot water and mineral ions
• move from roots to leaves
• very long and tube-like
• joined end to end without end walls to interupt the flow of water
• cells are dead thus containing no cytoplasm
• cell WALLS are impregnated with lignin
• lignin is either deposited in spirals or complete rings which allows flexibility and stops the stem from breaking
• as the cell gets older the ammount of lignin increases
• there are pits in the cell wall where there is no lignin present…