transport in plants Flashcards
dicotydelenous plants
have 2 dicotyledons- act as food stores for developing plat embryo plant and form 1st leaves when plant gemrinates
herbaceous dictos- soft tissues- short life cycle
woody dicots - hard tissues and long life cycle
bordered pits
water leaves out of the xylem and moves out into other parts of the cell!
osmosis
net movement of water from an area of high water potential to low water potential until equillibirium is reached !
advantages of turgor pressure ?
cell expanison, plant rots force way through tarmac/ concerete
what does loss of water do ?
keeps plant cool ( evaporation)
what happens after water reaches xylem in symplast
water potential of root hair cell cytoplasm falls again so that steep water potential gradient is maintained so lots of water can continue to move up to the cell from the soil
what keeps water moving in the apoplast pathway?
the pull from water moving into the xylem and up the plant and the cohesive forces between the water molecules to creat tension which causes continous flow of water through cellulose cell wall
advantage of symplast in the movement of water into the xylem through the endodermis
water must pass through selectively permeabel cell membranes- excludes toxic substances reach tissues
what happens once water is in the vascular bundle after arriving via symplast pathway from the endodermis
after it enters vascular buncle, it moves via apoplast pathway to enter xylem itself and moves up plant
how is root pressure causes
active pumping of minerals into xylem itself , produces movement of water via omosis which results in root pressure. root pressure pushes water up the xylem
evidence of active transport in xylem
all of it has to do with lack of energy being supplied for root pressure .
advantage of a waxy cuticle ?
prevents leaf cells from loing water rapidly via evaporation .
transpiration stream
water enters plant roots, transported up xylem, reaches leaves.
tehn moves by osmosis across membranes and by diffusesion into the apoplast pathway from xylem through cells of leaf
and then evaporates into the air via permeable cellulose cell walls of mesophyll cells
parenchyma and fibres in phloem
parenchyma: provides support
process of water movement through leaf cells
. water evaporates fro mesophyll surface into air spaces in leaf and move out of stomata into air by diffusion
.loss of water by evaporation from mesophyll cells lowers cell water potential thus water moves into cell from adjacent by osmosis via symplast + apoplast pathways
.repeated across leaf to xylem. water moves out of xylem by osmosis into cells of leaf
water molecule ahere to carbohydrates in xylem via hydrogen bonds, whilst also forming hydorgen bonds with each other ( cohesison ). capillary actionresults from combination of cohesion and adhaesion thus resulting in capillary action (Rising of water agaisnt gravity)
water drawn up by xylem in continous stream to replace water lot by evaporation ( transpiration pull)
.transpiration pull results in tension in xylem , helps water move from soil into roots
increase in transpiration results in ….
increase in tension thus increase in tree diameter. measure at day and ngith to proe cohhesion tension theory
in summary, what does tranpsiration do
cools leaf down, prevents heat damage,
disadvantage: so much water maybe lost whilst conditions are extreme eg, whilst platn is photosynthesising repidly . increased transpiration may cause in supply not meeting demand
why is it easy to measure water uptake of plant
99 percent of water is lost by transpriation, measured using potometer
effect of windspeed on rate of transpiration
air moving outside the leaf- carries away water vapour that has just diffusedo ut of the leaf- maintains high water vapour gradient
the process of phloem loading
soluble products of photosynthesis moved into phloem from sources by active process . sucrose= mai ncarbohydrate- not used as much as glucose this less likely to be metabolised during transport process
water follows sucrose by osmosis , what does this do ?
creates pressure of water that moves sucrose through phloem by mass flow
what does symplast involve
movement of molecuels through plasmodesmata
storage organs
tubers, tap roots etc…
plasmodesmata
hoelsi n whoch stuff goes through the cell membrane ( MEMORISE THIS !!!!!!!!!!)
