module 3 Flashcards
(29 cards)
at the arterial end, what is high and what is it compared to
(calculation)
high hydrostatic pressure = 4.6kPa
4.6 - 3.3 = 1.3
at the venous end, what is high and what is it compared to
(calculation)
high osmotic pressure = 2.3 kPa
2.3-3.3 = -1.1
what does the lymph contain
less oxygen and nutrients, contains fatty acids (from small intenstine)
how is the lymph transported
squeezing of muscles
what is the arrangement of the vascular bundle in the stem
around the edge
phloem on outer end
what is the arrangement of the vascular bundle in the root
x formation of the xylem
what is the arrangement of the vascular bundle in the leaves
xylem on the top
what drives cell expansion
turgor
how does the plant cool itself
loss of water by evaporation
what happens in apoplast pathway
water fills spaces between the open network of fibres in the cell wall
define the endodermis
layer of cells surrounding vascular tissue in roots
describe the structure and function of the casparian strip
waxy material made of suberin forming waterproof layer
forces apoplast into symplast
water must past through selective-barrier, so it excludes toxic solutes
describe the function of the endodermal
pumps ions into xylem
WP gradient established (xylem lower than endodermal layer)
increases rate of water moving by osmosis
when does water return to apoplast
to enter xylem
what makes up the root pressure
active pumping of ions+ osmosis = root pressure
independent of any effects of transpiration
what does root pressure do
gives water a push up the xylem
(not major factor)
define guttation
xylem sap is forced out special pores at the ends of the leaves when transpiration is low
describe the process of water going into mesophyll
water evaporate and move out stomata
loss of water lowers WP, so water moves into cell (from xylem to mesophyll)
what makes up capillary action
what is capillary action
adhesion + cohesion
water rises up a narrow tube against the force of gravity
define transpiration pull
water drawn up the xylem in continuous stream to replace water lost by evaporation
results in tensions in the xylem
what is evidence for transpiration
changes in the diameter of trees
when a xylem breaks, air is drawn in
what is ostia
fenestrations in the insect heart
how is a continous flow of water established in the xylem
more water is pulled through the apoplast into the xylem
pull from water moving into the xylem and up plant + cohesive forces = continous flow of water
what happens in diastole
pressure is low
pressure increases as the atria fill with blood
