mass transport plants Flashcards
xylem tissue function
transport water through stem up plant to plant leaves
adaptions of xylem tissue
cells joined with no end walls forming long continuous tube so water flows as continuous column
cells less organelles easier water flow with no obstructions
thick cell walls with lignin so withstand tension
pits in side walls allow lateral water movement
CT LEAF
Water lost from leave by transpiration - water evaporates from mesophyll cells into air spaces and WV diffuses through open stomata
reducing wp of mesophyll cells
so water drawn out xylem down wpg
xylem CTT
creates in yxlem
h bonds = cohesion between water molecules so water puled as continous column
water adheres to walls of xylem
roots ctt
water enters root via osmosis
how to set up potometer
cut shoot underwater at slant preventing water entering xylem
assemble potomètre with capillary tube end submerged in beaker of water
insert shoot underwater
ensure apparatus air and water tight
dry leaves
give time for shoot to acclimatise
shut tap to reservoir
form an air bubble and remove en of capillary tube from water
how can photometer be used to measure rate of transpiration
record position of air bubble
record distance moved in certain amount of tine
calculator volume of uptake in given time
use radius of capillary tube to calc cross sectional area of water
and multiply by this by distance moved by air bubble
calc rate of water uptake - divide volume by time
Describe how a potometer can be used to investigate the effect of a named
environmental variable on the rate of transpiration
carry out above and change on variable at a time wind light humidity temp
keep other variables constant
limitations of using photometer to measure transpiration rate
rate of water uptake might not be same as rate of transpiration
water used for support and turgidity
water used for photo and produced in respiration
rate of movement in shoot in photometer may not be the same as the rate of movement in the whole plant
shoot in potometer has no roots whereas plant does
xylem cells are very narrow
light intensity effect on transpiration
increases it
stomata open in light to let in co2 for photosynthesis
allowing water to evaporate faster
stomata close when its dark so lower transpiration rate
temp effect on transpiration
increase it
water molecules - higher ke
so water evaporates faster
wind intensity effect on transpiration
increase rate of transpiration
wind blows away water molecules from stomata decreases wp of air around stomata
incr WPG - water evaporates faster
humidity
decrease rate of transpiration
more water in air so it has hwp
decreases wpg from leaf to air
water evaporates slower
phloem tissue function
transport organic substances eg sucrose in plants
how is phloem tissue adapted to function
sieve tube elements no nucleus and few organelles so easier flow of organic susbtances
end walls between cells perforated forming sieve plates
companion cells many mito high rate of respiration to make ATP for active transport of solutes
