8a Flashcards
What is the most abundant molecule in plants?
Water
9 properties of water
Polar molecule, hydrogen bonding, hydration shells, liquid over a large range of temperatures, thermal conductivity, high heat of vaporization, solvent properties, biochemical reactions, transparency
Waters physiological roles?
Uptake to maintain turgor, nutrient carrier
Water cohesion: strong mutual attraction between water molecules is due to?
Hydrogen bonding
Water cohesion: what does it do to waters surface tension?
Gives high surface tension
Water cohesion: what is waters tensile strength?
Unusually high tensile strength (max tension that an uninterrupted column can withstand)
Water adhesion: what is water attracted to?
Solid surfaces
Water adhesion: what does this allow for?
Allows capillary rise in small- diameter columns
What is diffusion? How do particles move?
Simplest way of movement through a solution or across a membrane
Particles move from high concentration to low concentration
What is diffusion of water called?
Osmosis
What does water cross during osmosis?
A selectively permeable membrane
What is osmotic potential? Positive or negative?
The change in free energy or chemical potential of water produced by solutes
Negative
What is water potential?
The sum of osmotic potential and wall pressure - potential energy of water
What is water potential affected by?
Affected by how much is dissolved
What is osmotic pressure?
The pressure needed to stop water movement
What is osmotic pressure the difference of?
The difference in chemical potential of the two solutions
Water potential is designated as?
ψ psi (sigh)
Osmotic potential is designated as?
ψ pi
Pressure potential is designated as?
ψ p
Matric potential is designated as?
ψ m
Osmotic potential is the effect that…
Solutes have on water potential
What is pure water’s potential
0
What does solute addition do to potential?
Decreases potential
Osmotic potential is related to the number to of…
Particles in solution
What is pressure potential?
Pressure in excess of ambient atmospheric pressure
What effect does pressure have on water potential
Stretching or compression
Pressure potential units
MPa or bars
What is pure waters potential at 1 atmosphere?
Zero
Pressure potential is positive or negative?
Can be both
What is matric potential
Water adhesion to cell walls, membranes, soil particles
matric potential is positive or negative
Always negative
matric potential is important for _________, and ignored for __________ _______
Soils, living cells
Water moves to:
Moves to where water potential is more negative
Moves from high water potential to lower water potential
When does water move?
Whenever there is a difference in potential