Movement of water through roots Flashcards
what is a plants special exchange surface in the soil?
the root hairs
what is the casparian strip made up of?
waxy, waterproof substance
what are root hair cells responsible for absorbing?
water and mineral ions
how do plants constantly lose water?
by transpiration
why are root hair cells efficient surfaces for the exchange of water and mineral ions?
- they provide a large surface area
- they have a thin surface layer across which materials can move easily
where do root hair cells grown?
in the spaces around soil particles
why do root hair cells have a lower water potential than a soil solution?
root hair cells have sugars, amino acids and mineral ions dissolved into them. soil solution is mostly water.
how does water move from the soil solution to the root hair cell?
by osmosis
what are the two ways water can travel through the plant?
the apoplastic and symplastic pathways
what is the apoplastic pathway?
water travels through the cell walls
what is the symplastic pathway?
water travels through the cell cytoplasm
how does the apoplastic pathway work?
- water drawn into ENDODERMAL cells, pulls more water along behind- COHESIVE properties of water molecules
- creates TENSION draws water along cell walls of cell of root cortex
- mesh like structure of cellulose cell walls have many WATER FILLED SPACES
- so there is little/no resistance to pull of water along cell wall
how does the symplastic pathway work?
due to OSMOSIS
water passes through the cell walls along tiny openings PLASMODESMATA- each is filled with a thin strand of cytoplasm
therefore is a continuous column of cytoplasm.
