Water movement

What is water potential

difference in potential energy

between pure water and water in a system

What is osmotic potential

from dissolved solutes

What is pressure potential

from hydrostatic and

pneumatic pressures – turgor and transpiration

What is matric potential

cohesive and adhesive

forces of water

What must we have to have a functional plant

water potential gradient

Rank water potentials

Ψsoil > Ψroot > Ψstem > Ψleaf > Ψatmosphere

What does the water potential gradient drive

force for the water to move from soil, through plant, into atmosphere

What is transpirartion

the main driver of water movement in plant

How is tension created

by transpiration

What are the 5 forces that move water

diffusion, osmosis, capillary forces, hydrostatic

pressure, and gravity

What is cohesion

water molecules stick to each

other

What is adhesion

water molecules stick to

hydrophilic molecules (cellulose)

How does water move up narrow tubes

adhesion and cohesion combined into capillary action

What forces does capillary action generate

large tension (negative hydrostatic pressure)

Where does water vapor difuse from

open stomata

What does a boundary layer of a leaf do

prevents excessive diffusion, a undisturbed gradient of water vapor

What does a larger boundary layer mean

gentler gradiant→ slower rate of diffusion

What effect does wind have on transpiration

increases transpiration via thinning of the boundary level

What are the adaptations listed to prevent water loss due to wind

• Dense layer of trichomes

• Stomatal crypts – or sunken stomata

What occurs when stomata are illuminated

the concentration of solutes

in the vacuoles of the guard cells increases

What occurs in the stomata when the concentration of solutes increase

strach is converted to malic acid, protons pump expel protons which creates a gradiant across plasma membrane

What occurs inside the leaf during illumnation

Loss of water vapor reduces the water potential of

intercellular spaces, The increase in ΔΨ leads to evaporation of water from

cell walls,Drier cell walls have increased tension, bringing waterrom surrounding areas (including inside and outside

cells),When ΔΨ is transferred to cells near vascular tissue,

water will move in from the xylem

What does cohesion do in the xylem

hydrogen bonds pull in the rest of the water

column, transferring the tension

What does adhesion do

also transfer the tension to the

walls of the xylem – but walls are too rigid to

move