ch 36 Flashcards
3 mechanisms of plant transport
1) uptake and loss of water and solutes by ind. cells
2) short distance transport cell to cell
3) long distance transport of sap within xylem and phloem at the level of the whole plant
Water will always move across a membrane into the solution w the _
lower water potential
usually the more negative
Direction of flow is according to_
water potential
What is water potential
solute and pressure potential combined
What is solute potential
water moves in direction of solutes because they bind water so it cannot flow back
what is pressure potential
physical pressure of water
What is osmosis
diffusion of H20
the word potential in water potential refers to
waters potential energy- capacity to perform work
osmosis only works at
short distances
Long distance H2O movement via
bulk flow
transpiration
Ascent of Xylem Sap charactersitics
roots actively pump minerals in and water follows, moving upward
Transpiration (evaporative water loss) from leaves
What cohesion-adhesion
water molecules attract each other upwards ( cohesion) and waters hydrogen bond interaction w xylems cell walls ( adhesion)
What is the main force for water movement
Pulling
Stomata is the site for
evaporation
stomata allow for _ in photosynthesis and _ by product
Co2, 02
h20 exists what
h20 exists xylem in leaf vascular bundles and through the stomata
How does the stomata regulate gas/water exchange
by actively opening and closing
How do the stomata open and close
By guard cells
Characteristics of guard cells
open and close by changing shape
what are guard cells controlled by
the active pumping of potassium ions
guard cells turgid
stomata open
guard cells flaccid
stomata closed
Opening is triggered by
1) increased light
2) depletion of c02
3) circadian rhythms of opening and closing
closing is triggered by
1) water deficiency
2) high temperature