Water potential

Water potential

The force responsible for the movement of water in a system, measured in bars or mega

Solute potential/Osmotic potential (Ψs)

the tendency of water to move by osmosis (solute concentration)

Pressure Potential Ψp

results from exertion of pressure on membranes/walls as water moves in or out, can be positive or negative

What is the water potential of pure water?

Ψ = Zero, because pure water has the highest concentration of water molecules, and thus the highest water potential, the water potential of all other solutions must be lower than 0 (negative)

What does adding solute do to water potential

adding solute decreases water potential (the more solute, the more negative)

solute potential will always be ________ unless its pure water

a negative number

hypertonic solutions have what kind of solute potentials

negative solute potentials

formula for water potential

solute potential + pressure potential (Ψs+Ψp=Ψ)

What areas of water potential does water move to>

moves from areas of higher water potential to lower water potential (towards the more NEGATIVE, concentrated region)

Increasing the amount of solute in water will cause what for solute and water potential

Increasing the amount of solute in water will cause an INCREASE in solute potential and a DECREASE in water potential

Increasing water potential will cause what for pressure potential?

Increasing water potential will cause an increase in pressure potential

Decreasing pressure potential will cause what for water potential

a decrease in water potential

equation for solute potential

Ψs = -iCRT

i=

ionization constant

C=

molar concentration

R =

pressure constant

T=

temperature at Kelvin (273 + C)

Zucchini cores are measured and determined to have a sucrose concentration of 0/36 M. Calculate the solute potential Ψs of these cells (temp is 22 degrees). Will water go in or out of the plant cell?

Solute potential = -iCRT

i = 1

R = 0.0831

T = temp K (273 + C of solution)

Ψs = -8.83 bars

Water will move into the plant cells since the surrounding area is pure water at a concentration of 0, which is higher than -8.83. water moves from an area of higher water potential to an area of lower water potential.