Water Flashcards
what is water helpful for
transpirational cooling
photosynthesis
transport
turgor
what is it about H bonds and polarity of water that connects to thermal and physical properties
water can make H bonds which are much weaker than covialent bonds. there is an attraction between partial + and partial - charge on neighbor molecule. This means it can bond to any molecule with a charge. Polarity is responsible for soil and xylem flow because it allows water to connect to other surfaces and molecules too.
3 properties of water
high specific heat
solvent
cohesion and adhesion
High specific heat
it takes a lot of energy to change water temp by one degree
high thermal conductivity
plant can conduct heat away from site where the heat is generated ( cool down)
how does water absorbing and dissipating heat benefit the plant
good bulk flow- make or break H bonds
what about water makes it a good solvent
polarity
definition of ionic substance
charged
cohesion
water attracted to eachother via hydrogen bonds
what is stronger- cohesion or adhesion
cohesion
adhesion
attraction of water to soild surfaces
capillarity
cohesion and adhesion
what is smaller in phloem, tracheid’s or veins
tracheids
if cohesion is greater than adhesion what happens
water droplets
soil water repellancy
uneven wetting front- water puddles on dry dirt
why does soil water repellancy happen
organic matter is hydrophobic- you must apply a wetting agent for soil to be wet again
what are surfactants
aids in soil water repellency
what can cause hydrophobicity in soil
dead plant material - high net carbon creates parches that are hydrophobic. Also mycelium and roots secreting their substances.
does the transport of water occur actively or passively with bulk flow and diffusion
passively
bulk flow
Driven by pressure , transpiration, and gravity in plants
diffusion
direct movement of a substance from high concentration to low concentration
osmosis
diffusion of water across a selectively permeable membrane
what protein moves water in bulk
channel protiens
water moves from ___ free water to _____ free water
(More or less)
more free water to less free water
what is free water
water not attached to a solute (solute makes hydration shells around sugars)
TF selectively permeable membrane allows water to pass through but not solutes
T
The passive movement of water across a membrane is a combination of ___________ and __________- __________
diffusion and bulk flow
aquaporin
protein that allows water to pass through the membrane
water movement depends on a difference in ___________ of water in two parts of a system
chemical energy
water will move passively from ___ to _____ chemical potential
higher to lower
TF water moves passively and actively
F it only moves passively
how do plants control water movement
controlling solutes
is water potential positive
no it’s always negative
osmotic potential
change in free energy of water from dissolved solutes
what is pure waters solute potential
0
hypertonic
high solutes
hypotonic
low solutes
the more negative the water potential is, the (more/less) free water in the cell
LESS
turgor pressure
pressure potential in plants can be postive or negative
positive turgor pressure is in
insidde cells
negative turgor pressure is in
xylem
what organelle has the greatest influence on water potential and turgor pressure
vacuole
water potential gradients tell which direction water will move TF
T
osmotic adjustment
plants adjust their cell solute content to respond to drought
what is the mPa of saturation
0 MPA
What is field capacity
the amount of water the soil can hold against gravity
What is the mPa of the wilting point
-1.5 MPa
if the plants mPa is -1,5 mPa and the soils mPa is -0.01 then will water go in or out of the plant
in
air is typically -50 mPa. Will water normally go in or out of plant from air
out of plant into air
radial conductance what affects it
anatomy, cell wall permeability, activity of water channels
axial conductance
happens through xylem
what are the two ways that water can take axially
symplastically and apoplatistically
simplistically
water moving through the root through the cells (slower)
apoplastic movement of water
movement through cell walls of water. faster, but then the water must move symplastically through the endodermis
Casparian strip
Suberin filled strip that keeps water in the endodermis
what are the 2 points of resistance that water can hit when water moves into moves
- water moving vis apoplasticallt vs symplastically
- Casparian band
root traits affecting water uptake
hydraulic conductivity
total root mass
root length
root hair abundance
spatial distribution
when is it advantageous to have long roots (nutrients)
nitrogen deficient areas
phosphorous stays on the surface
what are the two cell types of xylem
tracheids and vessels
hollowed, thickened, conducting cells
tracheids
gymosperm
narrow
vessels
angiosperm
wide and short
what moves water faster, traacheids or vessels
vessels
capillary rise is inversely proportional to _____ and ________radius
tracheid and vessel
transpiration
flow of water from leaf to air
what is the major mechanism for long distance
transpiration
elements to water flow in leaves
veins -> mesophyll -> stomata -> air
what is the driving force for transpiration
differences in concentration of water vapor between leaf air spaces and the atmospheere
what factors impact transpiration
stomata, cuticle, mesophyll, boundary layer, temperature, vapor pressure gradient, environmental factors (transpiration)
what is the most important leaf specific factor that impacts transpiration
stomatal resistance (whether they’re open or closed)
mesophyll resistance
the less compact the mesophyll is in a lead, the less a chance the water has to get to the guard cell
what is the mesophyll
inner cells of a plant
cuticle resistance to water
epidermal cells are surrounded with a cuticle to prevent water loss
boundary layer
area outside of epidermal cells
the calm air that surrounds the exterior of the leaf
the boundary layer impacts how quickly the plant absorbs ___ and exports ___-
CO2 and O2
a thick boundary layer increases or decreases water vapor exititng
decreases because the relative humidity around a plant leaf is increased
does a thick boundary layer increase water loss
no it decreases it
does a thick boundary layer increase a plants ability to cool itself
no , it decreases it bc less transpiration
does a thick boundary layer decrease the amt of nutrients
yes
what impacts the boundary layer
leaf hairs
wind
leaf shape
environmental factors that affect transpiration
temperature
relative humidity
wind
solar radiation
water availability
how does temp impact transpiration
increases transpiration and kinetic energy of molecules
how does relative humidity affect transpiration
lowers transpiration rate and moves free water outside to increase the vapor pressure gradient
when is low humidity good in plants
flowering - less chance for diseases
what is high humidity good for
germination, grafting, and early propagation cuttings
how does wind affect the boundary layer
dissolves it
