2.3B Water transport Flashcards
what is transpiration
evaporation from leaves
what are the 3 section of water movement
- movement through roots
- movement through stem
- movement through leaf
what are the 2 paths that water moves through roots
- sympath pathway
- apoplast pathway
is apoplast or aeoplast faster
apoplast
what is the symplast pathway
- moves through the cytoplasm of one cell, to the cytoplasm of an adjacent cell (via plasmodesmata)
- moves across cortex via osmosis (down water potential gradient)
how does water move into root hair cells
via osmosis from soil
what is the apoplast pathway
- water moves within cell walls + spaces between cells
- quicker, water moves easily through cellulose fibres + less resistance to water flow
what is cohesion
when water molecules are attracted to eachother
(due to hydrogen bonds)
how is the apoplast pathway driven
by cohesion
how is the symplast pathway driven
by water potential gradient(between root hair cells and xylem)
what must happen before water can pass into the xylem (apoplast)
pass through a layer of cells: endodermis
what in the endodermis causes the apoplast pathway to stop
casparian strip
what is the casparian strip made of
Suberin (waterproof)
what does the casparian stip do?
disallow water to move via the apoplast pathway
how does water move after it has encountered the casparian strip
moves through cell membrane, into cytoplasm (becoming part of the symplast pathway)
This allows the cell membrane to choose what can enter the xylem
