chapter 9 - Transport in plants Flashcards
reasons why plants need transport systems
high metabolic demands for plants that dont photosynthesise
size- need transport system to move substances up and down plant
SA:V ratio - whole plant has relatively low sa:v ration therefore cannot rely on diffusion alone
what are dicotyledonous plants
make seeds that contain 2 cotyledonous , organs that act as food stores for developing embryo plants and forms first leaves when seed germinates
what are herbaceous plants
soft tissues with relatively short life cycle
what are woody dicots
hard lignified tissues and long life cycle
what is role of xylem
transport water and mineral ions
supports plants
what is the structure of xylem
non-living tissue
flows materials upwards
xylem vessels are long hollow structures made by columns of cells fusing together end to end
thick walled parenchyma packs around xylem vessels , storing food and containing tannin deposits
lignified walls
bordered pits where water leaves xylem
what is tannin
bitter chemical that protects plants from herbivores
what is the function of phloem
living tissue that transports food such as amino acids and sugar from leaves where they are made to cells that need it . flows up and down the plant
what is the structure of phloem
vessels of phloem are sieve tube elements made of cells joined end to end to form a long , hollow structure
between cells, walls become perforated to form sieve plates to let phloem contents through
tonoplast, nucleus and some organelles in cells breaks down
phloem filled with phloem sap and mature phloem cells have non nucleus
companion cells linked to sieve tube by plasmodesmata
why is water important for plants
- gives turgor pressure supports stem and leaves
- turgor drives cell expansion enabling roots to form their way through concrete
- loss of water by evaporation keeps plants cool
- mineral ions are transported in aquoues solutions
- water is a raw material for photosynthesis
adaptations of root hair
-microscopic so penetrate easily between soil particles
- large sa: ratio
- thin surface layer so diffusion and osmosis takes place quicker
- concentration of solutes in cytoplasm of root hair cells maintain water potential gradient between soil water and cell
what is the symplast pathway
water moves through symplast - continuous cytoplasm of living plant cells connected through the plasmodesmata by osmosis
what is the apoplast pathway
movement of water through apoplast - the cell walls and the intercellular spaces
what is the endodermis
layer of cells surrounding vascular tissue
contains casparian strip which is a band of waxy material called suberin forming waterproof layer
apoplast pathway is blocked and water if forced into cytoplasm of cell following symplast pathway
what is evidence of active transport of mineral ions in root pressure
poisons like cyanide affect mitochondria and production of ATP so root pressure dissapears as there is no energy for active transport
- root pressure increases with rise in temperature suggesting chemical reactions are involved
- if levels of oxygen fall, root pressure falls
- xyl
