724720
Descripción
Mapa Mental por HeatherTxo, actualizado hace más de 1 año
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Creado por HeatherTxo
hace más de 10 años
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Water Transport in plants.
- Water begins by moving into the root hair cells via osmosis down a water potential gradient.
- Ions move in by active transport.
- Ions move with water by either the symplast or apoplast pathway.
- Symplast pathway: Movement through cell cytoplasm
- Apoplast pathway: Movement through cell walls.
- Travel down a water potential gradient through
pathways via osmosis along the cortex until reaching the endodermis where
apoplast is restricted so all water and ions must enter
cytoplasm.
- Apoplast is restricted by casparian strip (waterproof strip)
- Ions are then actively transported into xylem to
lower water potential to allow water to travel
through via osmosis
- water creates hydrostatic pressure which helps push it up the xylem
- Xylem - cells with broken down
horizontal cell walls strengthened
by lignin to make thick hollow
'pipes'
- Water is pulled up via tension of the
continuous unbroken column of water due
to hydrogen bonds occuring between
molecules
- This is mass/bulk transport
- To reach the leaf osmosis occurs via apoplast or symplast
pathways and then transpiration occurs.
- Transpiration: Evapouration from the surface of
mesophyll cells into air spaces then diffusion out
through open stomata.
- Lost water is then replaced by
adjacent cells via pathways, so
more water is pulled from xylem
to replace loss and repeats.
- Transpiration: Evapouration from the surface of
mesophyll cells into air spaces then diffusion out
through open stomata.
- This is mass/bulk transport
- Xylem - cells with broken down
horizontal cell walls strengthened
by lignin to make thick hollow
'pipes'
- water creates hydrostatic pressure which helps push it up the xylem
- Apoplast is restricted by casparian strip (waterproof strip)
- Symplast pathway: Movement through cell cytoplasm
- Ions move in by active transport.
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