Chapter 30: Transport in Plants Flashcards
Plant roots take up _____ and _________ from the soil
water; minerals
Mineral uptake requires transport ___________
proteins
Some minerals enter the plant by ____________; others by _____________
facilitated diffusion; active transport
Water moves through biological membranes by _________, toward cells with more negative water potential
osmosis
Water moves toward solutions with higher __________ concentrations
solute
What causes the turgor pressure?
Plant cell walls resist pressure of water moving in
Water travels through ______________ layers to reach vascular tissue
several tissue
Vascular tissue in a central cylinder called the _________
stele
What is the Apoplast?
intercellular spaces and cell walls
What is the Symplast?
intracellular spaces (enclosed by membranes)
What is the Casparian strip?
waterproof layer between cells of the endodermis
In the The casparion strip; Water cannot pass ________ endodermal cells; must go ________
between; through
The casparion strip; Allows plant to control which _____________ cross
mineral ions
Water and minerals pass from the soil to the xylem via the _______ and _________
apoplast; symplast
In the root, water and minerals may pass from the cortex into the stele only via the symplast, because the ______________ blocks the apoplast route at the endodermis
Casparian strip
Once water enters stele:
Uptake of water/minerals into ____________
xylem cells
In plants, are the xylem cells dead and hollow?
yes
Xylem transport is the result of combined effects of ___________, __________, and __________
transpiration, cohesion, and tension
What is Transpiration?
evaporation of water from plant parts (especially leaves)
What is Cohesion?
tendency of water molecules to “stick” together (hydrogen bonding)
What is Tension?
negative pressure (pulls water upward from roots)
Evaporation from the leaf (= transpiration) produces _________ in the surface film of water on the mesophyll cells, pulling water and dissolved minerals up the xylem from the root
tension
Water evaporation _________ leaves, but a plant cannot afford to lose too much water
cools
Transpirational water loss is minimized by the leaves’ ___________
waxy cuticles
Stomata open and close via regulated changes in _____________
guard cell pressure
Process balances photosynthesis (CO2 uptake) and water loss via __________
transpiration
Organic solutes (e.g. sugars, photosynthetic products) are transported in the ________
phloem
Products of photosynthesis, and some minerals, are translocated through _________ in the phloem via living sieve tube members
sieve tubes
____________ proceeds in any direction in the stem, although in a single sieve tube it goes only one way
Translocation
What causes the phloem transport?
translocation
Translocation requires a ______________
supply of ATP
Translocation in the phloem proceeds in accordance with the _________________
pressure flow model
Difference in solute concentration between _________ and __________ allows a difference in pressure potential along sieve tubes, resulting in bulk flow
sources; sinks
Companion cells load _________ into sieve-tube members at _________
sucrose; source
__________ from xylem follows automatically, due to ________; increases _________ at source
Water; osmosis; turgor pressure
Companion cells ________ into sink cells
unload sucrose
Water exits sieve tube (back into xylem) via osmosis; __________ at sink
reduces turgor pressure
The pressure flow model succeeds because sieve plates are normally open, __________________,
and because neighboring cells _____________________________________ in source regions and ________________ regions
allowing bulk flow; load organic solutes into sieve tube members; unload them in sink
