water uptake and movement up stem (incomplete)
- Created by: Lois
- Created on: 08-01-13 12:09
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- Water uptake and movement in stem
- water uptake from soil
- plant roots - surrounded by soil particles. outermost layer of cells (apidermis) contains root hair cells that increase surface area
- these absorb minerlas from soil by active transport using ATP for energy
- minerals reduce water potential of cell cytoplasm - makes water potential in cell lower than soil
- water taken up across plasma membrane doing water potential grandient by osmosis
- minerals reduce water potential of cell cytoplasm - makes water potential in cell lower than soil
- these absorb minerlas from soil by active transport using ATP for energy
- plant roots - surrounded by soil particles. outermost layer of cells (apidermis) contains root hair cells that increase surface area
- cohesion: attraction of water molecules
- adhesion: attraction of water molecules in walls of xylem
- movement across root
- driven by active process that occurs in endodermis - layer of cells surrounding xylem, also know as startch sheath; sign energy being used
- endodermis consists of special cells that have waterprrof ***** in some of there walls: casparian *****
- casparian ***** blocks apoplast pathway forcing water through symolast pathway
- endodermis cells move mineral by active transport from cortex into xylem: decreasing xylem water potential
- so water moves by osmosis, reducing wp in cells outside endodermis. this combined with water entering root hair cells creates wp gradient across cortext
- water moved along symplast pathway from root hair cells across cortex into xylem. at same time water can move across apoplast pathway across cortex
- -water moves into cells to join symplast pathway just perfore passing through endodermis
- water moved along symplast pathway from root hair cells across cortex into xylem. at same time water can move across apoplast pathway across cortex
- so water moves by osmosis, reducing wp in cells outside endodermis. this combined with water entering root hair cells creates wp gradient across cortext
- endodermis cells move mineral by active transport from cortex into xylem: decreasing xylem water potential
- casparian ***** blocks apoplast pathway forcing water through symolast pathway
- endodermis consists of special cells that have waterprrof ***** in some of there walls: casparian *****
- driven by active process that occurs in endodermis - layer of cells surrounding xylem, also know as startch sheath; sign energy being used
- role of casparian *****
- blocks apoplast pathway, ensures water and dissolves nitrate ions pass into cytoplas, through cell membranes
- transporter proteins in cell membranes, nitrate can be actively transported - from cytoplasm of cortex cells to xylem
- lowers wp in xylem so water from cortex cells follows into xylem by osmosis.
- once water entered xylem it cannot pass back into cortex as apoplast pathway of endodermal cells blocked
- lowers wp in xylem so water from cortex cells follows into xylem by osmosis.
- transporter proteins in cell membranes, nitrate can be actively transported - from cytoplasm of cortex cells to xylem
- blocks apoplast pathway, ensures water and dissolves nitrate ions pass into cytoplas, through cell membranes
- how water up stem
- water uptake from soil
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