3.3 Passage of water through plant Flashcards
what percentage of water passing through a plant is used for photosynthesis?
1%
the 99% of water not used in photosynthesis evaporates from the leaves in which process?
transpiration
what is the highest water potential?
0 (pure water)
the more solute the ……. the water potential?
lower
the greater the number of water particles the …….. the water potential?
higher
what is water key in?
structure and metabolism of plants
turgor/hydrostatic pressure is a result of what?
osmosis
what does turgor/hydrostatic pressure create in plants?
hydrostatic skeleton
what does turgor drive in plants?
cell expansion
what does evaporation do to plants?
cools them down
mineral ions and products of photosynthesis are transported in what?
aqueous solutions
water is a raw material for what?
photosynthesis
does soil solution have a high or low water potential? why?
high it is mainly eater with small quantities of mineral ions
inside the root is there a high or low water potential?
low
why is there a low water potential in the root?
there are amino acids, mineral ions and sugars
water moves into the root hair cell down a what?
water potential gradient
how are root hairs an adaptation to help absorb water?
increase root surface area which increases speed of water uptake
how else are plant roots adapted to absorb water?
thin surface layer of cellulose wall and cell surface membrane (short diffusion distance)
what are the two routes which the water can move from the root hair cell into the xylem?
apoplastic pathway
symplastic pathway
what does the apoplastic pathway use?
the apoplast/outside
what does the symplastic pathway use?
the symplast/middle
water moves through the symplast by what process?
osmosis
(symplast) due to water diffusing in from soil the root hair cell has higher water potential than the next cell, so what does water do?
moves from root hair to next cell along by osmosis
(symplast) water moves from cell to cell until what is reached?
the xylem
(symplast) when the xylem is reached water moves through which p?
plasmodesma
what is the plasmodesma?
gaps between the cell
(symplast) as water leaves the root hair what happens to the water potential of the cytoplasm? what does this maintain?
it decreases
maintaining steep water potential gradient
in the apoplast pathway what does water fill?
spaces between network of fibres in cellulose cell wall
(apoplast) as water moves into the xylem, what happens to more water molecules?
pulled through apoplast due to cohesive forces between molecules
(apoplast) what do the cohesive forces between water molecules create?
tension
(apoplast) what does the tension of the water result in?
continuous flow of water through the cellulose wall with little or no resistance
in the apoplast pathway the water reaches the endodermis and the casparian strip, what is this?
waterproof band in the endodermal cells preventing the water from passing
what happens to the water reaching the casparian strip by the apoplast?
forced into protoplast (living part) joining water from symplast
what is the mechanism by which the water gets into the xylem from the symplast and apoplast?
active transport of salts into the xylem
when endodermal cells actively transport salts into the xylem what does it create and what does it result in?
lower water potential so water moves into xylem by osmosis
creating force moving water up the plant - root pressure
what happens to root pressure when temperature increases?
pressure increases
temperature increase will increase the rate of production of what?
ATP
why does increased temperature increase ATP production?
root pressure requires energy
ATP is produced by enzymes which work faster and more efficiently at high temperatures
how do metabolic inhibitors affect root pressure?
prevent energy release by respiration, no energy for root pressure
give an example of a metabolic inhibitor:
cyanide
