Water Relations Water Relations How water and minerals flow How water and minerals flow through the plant. through the plant.
Jan 16, 2016
Water RelationsWater Relations
How water and minerals flow How water and minerals flow through the plant.through the plant.
Water RelationsWater Relations
How water and minerals flow How water and minerals flow through the plant.through the plant.
Why does the plant need water?Why does the plant need water?
Water RelationsWater Relations
How water and minerals flow How water and minerals flow through the plant.through the plant.
Why does the plant need water?Why does the plant need water?• TurgidityTurgidity• growthgrowth• photosynthesisphotosynthesis• cooling (evaporative)cooling (evaporative)• solvent/metabolic mediumsolvent/metabolic medium
Movement of Water?Movement of Water?
Movement of WaterMovement of Water
Leaves ->Leaves ->
stem->stem->
roots ->roots ->
Leaf StructureLeaf Structure
Purpose of Stomata (?)Purpose of Stomata (?)
Purpose of Stomata (?)Purpose of Stomata (?)
Gas ExchangeGas Exchange
Purpose of Stomata (?)Purpose of Stomata (?)
Gas ExchangeGas Exchange• C02 and H20C02 and H20• TranspirationTranspiration
• Trade Off (?)Trade Off (?)
Purpose of Stomata (?)Purpose of Stomata (?)
Gas ExchangeGas Exchange• C02 and H20C02 and H20• TranspirationTranspiration• Trade Off:Trade Off:
– How can a plant take in adequate carbon How can a plant take in adequate carbon dioxide without losing too much water???dioxide without losing too much water???
– Natural adaptationsNatural adaptations
– Synthetic solutions - Synthetic solutions - antitranspirantsantitranspirants
Leaf StructureLeaf Structure
Leaf StructureLeaf Structure
Diffusion?Diffusion? (Much of what happens during (Much of what happens during
water transport depends on water transport depends on physical laws and the physical physical laws and the physical characteristics of water.)characteristics of water.)
DiffusionDiffusion
DiffusionDiffusion The movement of molecules from
an area of greater concentration to an area of lesser concentration.
TKE Translocational Kenetic Energy
Solute & SolventSolute & Solvent
Laws of Laws of ThermodynamicsThermodynamics
FirstFirst
SecondSecond
Laws of Laws of ThermodynamicsThermodynamics
FirstFirst• the total amount of energy in the the total amount of energy in the
universe is constant. Can change universe is constant. Can change from one form to another.from one form to another.
SecondSecond
Laws of Laws of ThermodynamicsThermodynamics FirstFirst
• The total amount of energy in the universe The total amount of energy in the universe is constant. Can change from one form to is constant. Can change from one form to another.another.
SecondSecond• The total amount of free (usable) energy is The total amount of free (usable) energy is
declining.declining.• Some energy lost as heat of every transfer.Some energy lost as heat of every transfer.
Osmosis?Osmosis?
OsmosisOsmosis
OsmosisOsmosis
The movement of water The movement of water through a differentially through a differentially permeable membrane.permeable membrane.
SolutionsSolutions
Hypotonic Hypotonic - lesser concentration of - lesser concentration of solute on the outside of the cell. solute on the outside of the cell. (Turgor Pressure)(Turgor Pressure)
SolutionsSolutions
Hypotonic Hypotonic - Lesser concentration - Lesser concentration of solute on the outside of the cell. of solute on the outside of the cell. ((Turgor PressureTurgor Pressure))
HypertonicHypertonic - Greater concentration - Greater concentration of solute on the outside of the cell. of solute on the outside of the cell. ((PlasmolysisPlasmolysis))
SolutionsSolutions
Hypotonic Hypotonic - Lesser concentration of - Lesser concentration of solute on the outside of the cell. solute on the outside of the cell. ((Turgor PressureTurgor Pressure))
HypertonicHypertonic - Greater concentration of - Greater concentration of solute on the outside of the cell. solute on the outside of the cell. ((PlasmolysisPlasmolysis))
IsotonicIsotonic - Equal concentrations of - Equal concentrations of solutes on the inside and outsides of solutes on the inside and outsides of the cell.the cell.
Plasmolysis & Turgor Plasmolysis & Turgor PressurePressure
Properties of Properties of WaterWater
1. Dipolar - 1. Dipolar -
Properties of Properties of WaterWater
Properties of Properties of WaterWater
1. Dipolar -1. Dipolar - 2. Universal solvent2. Universal solvent
Properties of Properties of WaterWater
Hydrated shells - Hydrated shells -
Properties of Properties of WaterWater
Properties of Properties of WaterWater
1. Dipolar -1. Dipolar - 2. Universal solvent2. Universal solvent 3. As solutes are added to pure water 3. As solutes are added to pure water
the boiling point increases and the the boiling point increases and the freezing point depression decreases.freezing point depression decreases.
Properties of Properties of WaterWater
3. As solutes are added to pure water 3. As solutes are added to pure water the boiling point increases and the the boiling point increases and the freezing point depression decreases. freezing point depression decreases. Freezing Point Determination for Freezing Point Determination for osmotic pressure (O)osmotic pressure (O)
Properties of Properties of WaterWater
Osmotic Osmotic pressurepressure
((OO))
Properties of Properties of WaterWater
Plasmolytic Method for (O)Plasmolytic Method for (O)• series of sugar solutions:series of sugar solutions:
• 0.2M 0.3M 0.4M 0.5M ………0.2M 0.3M 0.4M 0.5M ………
Incipient Plasmolysis Incipient Plasmolysis
Properties of Properties of WaterWater
Plasmolytic Method for (O)Plasmolytic Method for (O)• series of sugar solutions:series of sugar solutions:
• 0.2M 0.3M 0.4M 0.5M ………0.2M 0.3M 0.4M 0.5M ………
• use plant cells - epidermal tissueuse plant cells - epidermal tissue• check for check for incipient plasmolysis incipient plasmolysis OO solution solution
= = OO cells cells
Osmotic Potential (O) of a Osmotic Potential (O) of a PlantPlant
Gravimetric MethodGravimetric Method for O for O determination:determination:• 1. Series of Known sucrose solutions:1. Series of Known sucrose solutions:• 2. Cylinders of plant tissue in each solution2. Cylinders of plant tissue in each solution
– 0.5M -14.3 Bars0.5M -14.3 Bars– 0.55 -16.0 Bars0.55 -16.0 Bars– 0.60 - 17.7 Bars0.60 - 17.7 Bars
• 3. Determine wt. 3. Determine wt. LossLoss or or gaingain - (No change - (No change in wt. = O of plant cells.)in wt. = O of plant cells.)
Osmotic Potential (O) of a Osmotic Potential (O) of a PlantPlant
Chardakoff Falling Drop MethodChardakoff Falling Drop Method for for W determination:W determination:• 1. Series of Known sucrose solutions:1. Series of Known sucrose solutions:• 2. Cylinders of plant tissue in a series of 2. Cylinders of plant tissue in a series of
each solution and MB in another serieseach solution and MB in another series– 0.5M -14.3 Bars tissue … MB0.5M -14.3 Bars tissue … MB– 0.55 -16.0 Bars tissue … MB0.55 -16.0 Bars tissue … MB– 0.60 - 17.7 Bars tissue … MB0.60 - 17.7 Bars tissue … MB
• 3. If 3. If tissuetissue absorbs water (O > sol) = absorbs water (O > sol) = drop risesdrop rises
• If tissue emits water (O < sol) = drop If tissue emits water (O < sol) = drop fallsfalls
Overall Water Status of a Overall Water Status of a PlantPlant
Water Potential (W) =Water Potential (W) = Osmolarity (Osmolarity (OO) + Wall Pressure ) + Wall Pressure
(P)(P)
W = W = OO + P + P
Overall Water Status of a Overall Water Status of a PlantPlant
• Pressure Bomb MethodPressure Bomb Method for for determining W:determining W:
• (direct measurement - most accurate)(direct measurement - most accurate)
– 1. Place plant part in pressure chamber 1. Place plant part in pressure chamber with cut stem on the outside. (Cut stem with cut stem on the outside. (Cut stem usually shows water under tension.)usually shows water under tension.)
– 2. Increase pressure inside of chamber 2. Increase pressure inside of chamber until water droplets pushed out of cut until water droplets pushed out of cut stem. Pressure reading at this point = Wstem. Pressure reading at this point = W
Overall Water Status of a Overall Water Status of a PlantPlant
• Water Potential ( W)Water Potential ( W)
• Water tends to move from cells Water tends to move from cells that have relatively high (less that have relatively high (less negative!) water potentials to negative!) water potentials to cells that have lower (more cells that have lower (more negative) water potentials!!negative) water potentials!!
Overall Water Status of a Overall Water Status of a PlantPlant
• Water Potential ( W)Water Potential ( W)
• ……………………………………………………....
Overall Water Status of a Overall Water Status of a PlantPlant
• Water Potential ( W)Water Potential ( W)
• Water tends to move from cells Water tends to move from cells that have relatively high (less that have relatively high (less negative!) water potentials to negative!) water potentials to cells that have lower (more cells that have lower (more negative) water potentials!!negative) water potentials!!
• Soil --> Root --> Stem --> Leaves --> Soil --> Root --> Stem --> Leaves --> AtmosphereAtmosphere