Quiz two questions Flashcards
list 3 physical properties of water
high tensile strength, low viscosity, and cohesive
what is the importance of high tensile strength of water?
adds structural support in the xylem of tall plants
what is the importance of low viscosity of water
facilitates the transport of water by providing less frictional resistance to the movement of water in the xylem
what is the importance of cohesion of water
it allows the water column to remain intact which prevents cavitation
water potential=
solute potential + pressure potential
what is the water potential of a plant that is turgid?
greater than 0
what is the water potential of a plant that is wilted?
less than or equal to 0
within a soil-plant-atmosphere continuum when water moves from the soil to the top of the plant where is the highest water potential found?
soil
within a soil-plant-atmosphere continuum is water potential in the soil positive or negative?
negative
movement of water from the soil into the roots is ______ transport
short distance
movement of water from the soil into the roots happens via
diffusion
movement of water from the roots to the top of the plant is ______ transport
long distance
movement of water in long distance transport happens via
mass flow
what are the two forces long distance transport can be driven by?
root pressure and transpirational pull
root pressure only aids in long distance transport of what types of plants
short
define an embolism
break in the water column
why is an embolism bad for plants
it causes damage to the xylem which may be long term; it can also negatively effect future water transport
what is a structural feature of xylem tissue that help minimize embolisms and why
the vessels are interconnected and this allows the lateral flow of water which detours water around the blocked vessels
what physical property of water helps minimize embolisms and why
high tensile strength because it keeps the water column intact
define guttation
the release of water from pores called hydathodes at the end of leaf veins
what causes guttation
high root pressure in plants
what conditions promote guttations
high soil moisture, plenty of mineral content in the soil, relatively high humidity, and stomata closed
what plants do guttation occur in
strawberries or turf
what are the protein pores that the bulk of the water that moves in and out of plants cells called
aquaporins
the transport of water through aquaporins is called
symplast
once water reaches the ____ cell layer it must travel by ____ only
endodermis; symplast
why must water travel only by symplast when it reaches the endodermis?
casparian strips in the endodermis cell walls block apoplastic water movement
relative humidity=
(actual mass of water vapor in an air mass/mass of water vapor air can hold at saturation) X 100
what does VPD stand for?
vapor pressure deficiet
how does VPD influence plant water status?
influences the rate a plant transpires which effects the overall water potential of a plant
how are plants able to use osmoregulation to survive dry soil conditions
they lower their cells’ water potential by increasing the solute level in the cells (produces sugars alcohol etc) which brings total water potential below the soils allowing the roots to take up water
