plant transport Flashcards
transpiration
loss of water vapour form the stomata due to evaporation
where does transpiration usually occur
leaves and stem
factors that increases rate of transpiration [2]
- increased temp
- decreased humidity
how does water affect transpiration
cohesive- hydrogen bond forms with each other
adhesive- water column is continuous
adaptations of xylem [5]
- hollow + made from dead cells
- no need for osmosis
- less obstruction - absent end walls
- continuous flow of water - lignin
- prevent xylem from collapsing - pits for water to enter and exit
- narrow
- capillary action
diagram of stem
xylem inside
phloem outside
diagram of root
xylem- star
phloem- circles
function of xylem
transports water from the roots up the stem and leaves
function of phloem
transport sucrose from the leaves to the roots
function of cortex
unspecialised cells that bulk out the root to strengthen it and increase surface area
function of endodermis
inner skin of cells that water must pass through to reach the xylem
epidermis
absorbs water and mineral ions from the soil often using long narrow root hairs
what does the companion cells use
co-transporter protein to transport sucrose and h+ ions form the source
flow of sugars in phloem [4]
- leaf cells produce sugars by photosynthesis
- sugar transported form cell to cell in leaf
- solutes actively transported into phloem
- water diffuses into phloem
phloem loading
source making sucrose bc photosynthesis
how is proton concentration gradient maintianed
companion cell using atp to transport h+ to the source cell
root pressure
positive pressure potential generated in xylem by active transport of mineral ions from roots to xylem
movement of ions into the xylem
higher solute concentration in the xylem than in surrounding soil
pressure
drives water and dissolved minerals up the plant’s stem
pressure at leaves
negative hydrostatic pressure
plasmodesmata
channels through the cell walls of plant cells that connect neighbouring cells
apoplast pathway
pass thru the cell wall
- fast
symplast pathway
goes thru cell (cytoplasm and vacuoles) to travel between cells
- slow
how does water enter cytoplasm + result
osmosis by capillary action
- increased hydrostatic pressure
how do mineral ions enter the root hair cells
active transport
what happens when water leaves apoplast
enters endothermis
from synoplast
why does water go up the xylem
difference in hydrostatic pressure potential
concentration of sucrose, water and turgor pressure at the source
s- high
w- low
t- high
concentration of sucrose, water and turgor pressure at the sink
s- low
w- high
t- low
how does cohesion help water travel up the stem
dragged up using shoot tension
why is water vapour lost
diffusion thru large amount of stomata
function of sieve tube element
active translocation
function of companion cell
take sucrose from the leaf
- facilitated diffusion + active transport
lateral sieve area
plasmodesmata
