Water Material

• A. Bulk flow
• - Groups of water molecules
• -All going the same direction
• - influence by pressure and gravity (positive and negative)

• B. Simple Diffusion
• -movement of molecules with a gradient
• -Affected by concentration of molecules
• -temperature

• C. Osmosis
• -diffusion across a membrane
• - Affected by: solute concentration

Water Potential is a property of water at a specific location within or around a plant which when compared with the water potential of water at another location---> direction the net movement of water will be.

Factors that influence it

• -The concentration of solutes in the water and by pressure affecting the water.
• (water molecules --> simple diffusion)- higher concentration = higher water potential (vice versa)
• (solutes molecules--> osmisis)
• higher concentration= lower water potential (vice versa)

-The pressure that acts on the water can be either positive or negative. --> Bulk flow

• higher pressure= higher water potential
• lower pressure= lower water potential

-In tall plants, gravity affects the movement of water up the stem beccause a column of water has weight ---> Bulk flow affect in tall plant

greater pull of gravity= Lower water potential at bottom of plant, higher at top (visa versa)

-In the ground the attraction of water molecule for soil patricles (matrix effects) can affect the plant's ability to get water.

Increase matrix effects=lower water potential (visa versa)

• 1. Transpiration
• 2. Lowers water potential in the leaf
• 3. Neagtive Pressure
• 4. Pulls water into the leaf from the stem
• 5. Negative pressure in stem and root
• 6. Water pull ed in from ground

Symplasts: All the protoplast of a plant and the plasmodosmata connecting them. (An open space inside the cell)

Apoplast: All the cell walls and intercellular spaces in a plant.

A. Bulk Flow- water pulled into xylem from ground by negative pressure.

• B. Ions and osmosis
•   1.) Ion pumps in roots cells, pump in needed ions from apoplast into symplast.
•  2.) Osmosis from apoplast to symplast.
•  3.) Ions pumped from symplast to root xylem (apoplast)
•  4.) Osmosis from symplast to xylem.

• A. Water moving into root in symplast and apoplast
• B. Cells pump ions out of apoplast into symplast.
• C. Water reaches endodermis

Water reaches endodermis

• 1.) Structure
• -Casparian strip in cell wall.
• -Cell Wall impregnated with subern.

• 2.) Water and ion flow
•  a. Water/ions in symplast keeps moving.
•  b. Casparian strip blocks apoplast
•  c. Everything in apoplast must enter symplast to continue. Filters out undesirable ions.
•  d.Ions pumped from parachyma cells into conducting cell. Followed by osmosis.

• I. Anatomy- Ring of bundles --> dicot
• II. Holding water columns together
•  A. Cohesion (water molecules attach to each other by hydrogen bonds)
• - water: entire molecules is polar
• - ethanol: -has an oxygen, -strong attrach for electrons, -partly polar

B. Adhesion (water molecules attracted to inner surfaces of tracheary element cell walls.)

III. Forces acting on water columns

• A. Negative Pressure: affected by speed of transpiration
• B. Gravity
• -varies with height: 
•   Tall -heavier column-greater effect
•   Short - less leaves- less effect
• -diameter of tracheary elements
•   wider-more effect
•   Small- less effect
• C.Matrix effect- proportional to water in soil.
• - more water= less matrix
• - less water = greater matrix

All these things affect whether they move and how fast the water moves

• IV. When water columns breaks
• -significant forces up and down

• I. Leaf anatomy
• II. Water movement
• -out of xylem
• - forms films around all cells
• - cells pump ions out of water into cells.
• III. Source of negative pressure 
• -film of water diffuses out  and water evaporates
•    -greater liquid surface area (Increase surface tension and more water moves in to add to thickness of films).

• 
• I. Phloem tissue 
•  (Sieve tube member, companion cell, parenchyma, collenchyma, and sclerenchyma fibers)

Sieve tube member and companion cells are sugar conduction. (each sieve tube has a compansion cell attach to it)

• III. Function
• A. Companion cell sucrose pumps (pump sucrose into the system)
• B. Osmosis into system (pressurizes it)
• C. Sucrose pumped out at destination
• D. Osmosis out of system lowers pressure.
• E. Controls flow from high pressure to low.