Xylem

Front 1

Describe structure of xylem tissue

Back 1

-Long cells arranged end-end form continuous column.
-consists of tubes to carry water and dissolved minerals,fibers to support plant & living parenchyma cells.
-Thick walls impregnated by lignin which waterproofs walls of cells and cause mature cells to die.
-end walls decay.

Front 2

Explain lignin

Back 2

-waterproofs thick walls - cell contents die.
-strengthens the vessel walls and prevents vessel from collapsing- leaves vessels open.
- lignin thickening forms a pattern in cell wall:
spiral, annular (rings),network of broken rings-prevents vessel from being too rigid, allows flexibility.
-incomplete lignification leaves pores (pits/bordered pits)
-allow water to leave one vessel and pass into another adjacent vessel or living parts of cells.

Front 3

Adaptions and functions of xylem tissue

Back 3

- made from dead cells , form continuous column.
-narrow tubes -so water column does not break easily and allow effective capillary action.
-pits in lignified walls allow water move sideways
-patterns formed by lignin allow xylem to stretch as plant grows.

Front 4

Why is the flow of water not delayed or prevented?

Back 4

-no end walls
-no cell contents
-no nucleus or cytoplasm
-lignin thickening prevents walls from collapsing