Water Relations b How water and minerals flow 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?



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 (?)


Gas ExchangeGas Exchange


Gas ExchangeGas Exchange• C02 and H20C02 and H20• TranspirationTranspiration

• Trade Off (?)Trade Off (?)


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

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 -


1. Dipolar -1. Dipolar - 2. Universal solvent2. Universal solvent


Hydrated shells - Hydrated shells -


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.


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)


Osmotic Osmotic pressurepressure

((OO))


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


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


• 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


• 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!!



• ……………………………………………………....



• 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

Water Relations b How water and minerals flow through the plant.

Documents

Transcript of Water Relations b How water and minerals flow through the plant.