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Types of water movement in plants and factors that influence each type
- 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
- C. Osmosis
- -diffusion across a membrane
- - Affected by: solute concentration
Water potential: what it is, the factors that influence it, and how they influence it.
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)
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)
Water movement in Plants
- 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
What the symplast and apoplast are
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.
(Roots) how water and ions get into and through the root and its cells
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.
Water movement in root
- A. Water moving into root in symplast and apoplast
- B. Cells pump ions out of apoplast into symplast.
- C. Water reaches endodermis
(Roots) Characteristics of the endodermis and Casparian strips; how the endodermis affects the movement of water and ions; what its functions are
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.
(Stems.) How water columns stay together
- 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
(water molecules attracted to inner surfaces of tracheary element cell walls.)
(Stems): the three water potential factors that affect water movement in the stem, how theyaffect water movement, and how they might vary
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
Leaves. Leaf anatomy; where water goes inside and outside the leaf; how negative pressure is generated.
- 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).
Phloem structure. The cells involved in conducting sugar; the structure, contents, and relationship of sieve tube members and companion cells.
- 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)
Phloem function. How sugar gets into and out of the conducting cells of phloem. How sugar moves in the phloem from one part of the plant to another.
- 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.
Light independent reaction. Where it occurs: the three stages of the LI reaction andwhat happens in each.
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