4 - plant stem and transport

what is the epidermis

a single layer of cells covering the entire outside of the plant for protection

what is the parenchyma/ground tissue /4

cells specialised for:

* photosynthesis,
* storage
* support

what is the vascular tissue involved in /2 (TS)

transport and support

explain the structure of xylem vessels /6

* cellulose microfibrils in cell walls,
* thickened with lignin,
* continuous column made of hollow, dead cells with no end wall
* no cell contents,
* pits in walls,
* open ends

explain the function of xylem vessels /2

* transport of water and dissolved mineral ions from root and leaves,
* structural support

explain the structure of the phloem /6

* has a cellulose cell wall,
* sieve tube elements have thin peripheral cytoplasm
* very few organelles,
* have sieve plates and sieve pores,
* a companion cell is linked to each sieve tube element by plasmodesmata,
* living tissue

explain the function of the phloem

transport of organic solutes (sucrose, amino acids) from source to sink in a process called translocation

explain the structure of the sclerenchyma fibres (6)

fibres/cells have

• cellulose cell walls

• which are thickly lignified,

• dead and hollow cells when mature,

• often have pits in their walls,

• long narrow cells,

• usually pointed at both ends

explain the function of the sclerenchyma tissue

only structural support

what is the cambium

the layer of unspecialised cells that divide to give rise to the specialised xylem and phloem

what is the collenchyma tissue

cells found around the outside of the stem to give strength and stretch as the plant grows