WATER AND CELL TRANSPORT, XYLEM TRANSPORT, AND PHLOEM TRANSLOCATION.

Distribution of Earth's water supply

Saltwater - 97.5%
Freshwater - 2.5%

Freshwater distribution

Lakes and rivers - 0.3%
Groundwater - 30.8 %
Glaciers and permanent snow cover - 68.9%

Technologies to increase water availability:

• Digging wells to get groundwater
• Collecting rainwater
• Desalination

1 week

Average residence time for water molecules

Biospheric

1.5 weeks

Average residence time for water molecules

Atmospheric

2 weeks

Average residence time for water molecules

Rivers

2 weeks - 1 year

Average residence time for water molecules

Soil moisture

1 - 10 years

Average residence time for water molecules

Swaps

10 years

Average residence time for water molecules

Lakes and Reservoir

4,000 years

Average residence time for water molecules

Oceans and seas

2 weeks - 10,000 years

Average residence time for water molecules

Groundwater

1,000 - 10,000 years

Average residence time for water molecules

Glaciers and permafrost

Chemical properties

• Universal solvent
• temperature regulator
• Protectant
• Lubricant
• high specific heat capacity
• high heat conductivity
• buffered medium
• cohesion-adhesion property

Biological properties

• Dissolve minerals and nutrients for use of organisms
• Medium in fertilization of gametes
• Dispersal of seeds
• Reagent in photosynthesis
• Habitat

Unique properties of water

1. Water is polar
2. Water is an excellent solvent
3. Water has high heat capacity
4. Water has high heat of vaporization
5. Water has cohesive and adhesive properties
6. Water is less dense as a solid than a liquid

solid

Water is less dense as a \___________ than a liquid

liquid

Water is less dense as a solid than a \______________

WATER POTENTIAL

measure of the potential energy in water, specifically, water movement between two systems.

water movement

WATER POTENTIAL is the measure of the potential energy in water, specifically, \__________________ between two systems.

two systems.

WATER POTENTIAL is the measure of the potential energy in water, specifically, water movement between \_________________

WATER POTENTIAL

difference in potential energy between any given water sample and pure water

potential energy

WATER POTENTIAL is the difference in \________________ between any given water sample and pure water

any given water sample
pure water

WATER POTENTIAL is the difference in potential energy between \______________________ and \________________________

Greek letter
Ψ (Trident)

WATER POTENTIAL is denoted by the \____________

megapascals (Mpa)

WATER POTENTIAL unit is

unit of Water Potential

megapascals (Mpa)

Zero 0

Potential of pure water (Ψpure H2O) is

Ψsystem \= Ψs + Ψp

Water potential measurement combines the
effects of solute concentration (s) and pressure (p)

solute concentration

In water potential measurement, the s stands for

pressure

In water potential measurement, the p stands for

solute potential

In water potential measurement, the Ψs stands for

Ψp

In water potential measurement, the Ψp stands for

Inversely proportional

High solute
Low water potential

Relationship of Solute and Water Potential

Direct proportional

High pressure
High water potential

Relationship of Pressure and Water Potential

SOLUTE POTENTIAL

Also called 'osmotic potential'

osmotic potential

SOLUTE POTENTIAL is also called

NEGATIVE

SOLUTE POTENTIAL in plant cell is\_______________

plant cell

has NEGATIVE solute potential

ZERO

SOLUTE POTENTIAL in distilled water is\_______________

distilled water

has ZERO solute potential

PRESSURE POTENTIAL

Also called 'turgor potential'

turgor potential

PRESSURE POTENTIAL is also called

negative
positive

PRESSURE POTENTIAL may be \_____________ or \_______________

lowers Ψs (solute potential) causing water to move right side of the tube because

pure water + adding more solute to the RIGHT side

left side increases Ψp
causing water to move right side of the tube

pure water + positive pressure to the LEFT side

left side lowers Ψp
causing water to move to the left side of the tube

pure water + negative pressure to the LEFT side

high-water potential

Water transport pathways

Water moves from areas of \____________

water

\__________ moves from areas of high-water potential

tension

\______________________ is generated by the evaporation of water molecules during leaf transpiration and is transmitted down the continuous, cohesive water columns

evaporation of water molecules

tension is generated by the \_____________________________ during leaf transpiration and is transmitted down the continuous, cohesive water columns

leaf transpiration

tension is generated by the evaporation of water molecules during \______________________ and is transmitted down the continuous, cohesive water columns

transmitted down the continuous, cohesive water columns

tension is generated by the evaporation of water molecules during leaf transpiration and is \_____________________________

tension
evaporation of water molecules
leaf transpiration
transmitted down the continuous , cohesive water columns

\_______________ is generated by the \____________________________ during \_________________ and is \____________________________

Cohesion
adhesion

\________________ and \__________________ draw water up the xylem

up

cohesion and adhesion draw water \___________ the xylem

Negative water

\___________________________ potential draw water into the root

into

Negative water potential draw water \_____________ the root

Ghent microCT facility.

Three dimensional reconstructions of xylem imaged at the \________________

continues

Negative water potential \________________ to drive movement once water (and minerals) are inside the root;

water (and minerals)

Negative water potential continues to drive movement once \_______________ are inside the root

Negative water potential

continues to drive movement once water (and minerals) are inside the root

root

Ψ of the soil is much higher than Ψ or the \_________

soil

Ψ of the \__________________ is much higher than Ψ or the root

stele (location of the root vascular tissue).

Ψ of the cortex (ground tissue) is much higher
than Ψ of the \______________________________

cortex (ground tissue)

Ψ of the \________________ is much higher
than Ψ of the stele (location of root vascular tissue)

❑Symplast
❑Transmembrane
❑Apoplast

Movement of water and nutrients in the roots

same or shared

"sym" means

symplast

shared cytoplasm.

Symplast

In this pathway, water and minerals move from the cytoplasm of one cell in to the next, via plasmodesmata that physically join different plant cells, until eventually reaching the xylem.

plasmodesmata

In this pathway, water and minerals move from the cytoplasm of one cell in to the next, via \_________________ that physically join different plant cells, until eventually reaching the xylem.

TRANSMEMBRANE PATHWAY

In this pathway, water moves through water channels present in the plant cell plasma membranes, from one cell to the next, until eventually reaching the xylem.

water channels

In this pathway, water moves through \_____________________ present in the plant cell plasma membranes, from one cell to the next, until eventually reaching the xylem.

plasma membranes

In this pathway, water moves through water channels present in the plant cell \__________________, from one cell to the next, until eventually reaching the xylem.

"outside of," apoplast is outside of the cell.

APOPLAST
"a" means

APOPLAST

In this pathway, water and dissolved minerals never move through a cell's plasma membrane but instead travel through the porous cell walls that surround plant cells.

porous cell walls

In this pathway, water and dissolved minerals never move through a cell's plasma membrane but instead travel through the \____________________that surround plant cells.

OSMOSIS

WATER MOVEMENT BETWEEN CELLS

movement of water molecules from a solution with a HIGH concentration of water molecules to a solution with a LOWER concentration of water molecules

Tonicity

degree to which a particular cell is able to withstand changes in osmotic pressure

withstand
osmotic pressure

Tonicity is the degree to which a particular cell is able to \____________ changes in \_______________

Crenation

Shriveling of the cell due to dehydration in hypertonic solution; plasma membrane appears scalloped or notched

hypertonic solution

Crenation is shriveling of the cell due to dehydration in \_____________; plasma membrane appears scalloped or notched

scalloped or notched

Crenation is shriveling of the cell due to dehydration in hypertonic solution; plasma membrane appears \_______________

ISOTONIC SOLUTION

a solution that has the same solute concentration as another solution.

there is no net movement of water particles, and the overall concentration on both sides of the cell membrane remains constant

HYPERTONIC SOLUTION

a solution that has a higher solution concentration than another solution

water particles will move out of the cell, causing CRENATION

HYPOTONIC SOLUTION

a solution that has a lower solute concentration than another solution

water particles will move into the cell, causing the cell to expand and eventually lyse.

isotonic solution

IN PLANT CELL

no net movement of water particles

cell membrane is attached to cell wall

hypertonic solution

IN PLANT CELL

water particles move out of the cell

cell membrane shrinks and detaches from cell wall (PLASMOLYSIS)

hypotonic solution

IN PLANT CELL

water particles move into the cell

cell wall counteracts osmotic pressure to prevent swelling and lysis

Osmotic pressure
Solute potential
Turgor pressure

WATER MOVEMENT BETWEEN CELLS Is Affected by:

Osmotic pressure

as the water enters freely, the membrane obstructs passage of solutes giving rise to osmotic pressure

Solute potential

solute potential exhibited by a solution

Turgor pressure

pressure exerted by the protoplasm equally but opposite to the pressure exerted by the cell wall

Absorption

WATER MOVEMENT FROM SOIL TO ROOT XYLEM

\______________ occurs along a gradient that exists between the absorptive surface of the root hairs (rhizines) and the thin layer of the soil surrounding them.

absorptive surface of the root hairs (rhizines)
thin layer of the soil surrounding them

Absorption occurs along a gradient that exists between the \____________________ and the \_________________________.

Rhizine cells
Cortical cells (extracellular and intracellular pathway)
Endodermis (apoplast is blocked by the casparian strip)
Xylem

WATER MOVEMENT FROM SOIL TO ROOT XYLEM

flow from rhizines to xylem

casparian strip

blocks the updown flow of wayer and to succesfully employ natural

• Development of total absorptive surfaces (rhizines)
• Rate of respiration of rhizines
• Osmotic potential of rhizines
• Temperature
• Lack of oxygen
• Carbon dioxide content
• Vegetative profile

Rate of water uptake by the root system depends on:

Rate of water uptake by the root system depends on:

• Development of total absorptive surfaces (rhizines)
• Rate of respiration of rhizines
• Osmotic potential of rhizines
• Temperature
• Lack of oxygen
• Carbon dioxide content
• Vegetative profile

WATER MOVEMENT FROM SOIL TO ROOT XYLEM

rhizine cell
cortical cells
endodermis
xylem
build up of solutes in xylem
decrease in xylem psi (pressure / pound per square inch)
leading to HYDROSTATIC PRESSURE/ROOT PRESSURE
plants exhibit guttation

Guttation

exudation of drops of xylem saps on the edges of leaves
drops are rich of minerals
mostly exhibited by grasses