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how is root pressure generated?
water flowing in from the root cortex
describe the transpiration-cohesion-tension mechanism
water is pulled up from negative pressure in xylem. water vapor in airspaces of leaf moves down its water potential gradient and exits the leaf from stomata which lowers pressure in mesophyll. transpiration produces negative pressure which pulls the water in the xylem and into the leaf
how does transpiration produce negative pressure in the leaf and what effect does this have on transport of water in the xylem?
the water evporates so it pulls the water up the xylem (like a straw)
what role does cohesion and adhesion in water molecules play in water transport?
the water molecules are attracted to cellulose in the xylem
descirbe the structure of stomata
pores called stoma surrounded by a pair of guard cells
what controls the opening and closing of guard cells? what role does this play in transport?
changes in turgor pressure. this allows for uptake and loss of K+ ions
what are the stimuli for stomata opening and closing?
it opens during the day triggered by light, CO2 depletion, and an internal clock. it closes at night to minimize water loss
why is abscisic acid produced and what does it do?
it is produced when there is water deficiency and it closes the stomata
what is crassulacean acid metabolism (CAM)?
it is when stomatal gas exchange occurs at night
how is sugar loaded into sieve tube elements?
through active transport
descirbe bulk flow by positive pressure in a sieve tube
the sugars are loaded into sieve tube elements which creates a high pressure region and forces sab to sink tissues
how is positive pressure generated and what role does it play in the transport of sugar?
it is generated by active loading of sugars into sieve. it draws in water and increases pressure
guttation
water and dissolved minerals/sugar are exuded from tips of plants (like dew in the grass)
cavitation
when a vapor phase is introduced to xylem water column, creating trapped gas bubbles (embolism)
Note 
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