Transcript Ch 36 - MsBabbey

Chapter 36
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Leaves absorb gasses
and make sugar
Roots absorb water
and minerals
These items need to
be moved throughout
a vascular plant
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Proton Pumps use energy from ATP to pump
H+ ions out of plant cells to form an ion
gradient
This gradient stores energy which can then
be used to transport things through a plant
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Osmosis is the passive transport of water
from high to low concentration
Water potential (psi) is the combined effects
of solute concentration and physical pressure
Pure water is 0, whenever you add solute
water potential becomes negative (there is
less free water in solution)
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Aquaporins are selective channels in plasma
membranes that allow water to cross
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Vacuoles are the big things in plants that
store water
The membrane of a vacuole is called the
tonoplast
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When plant cells cytoplasm is connected, this
is called symplast
When cell walls are connected, this is called
apoplast
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It would take decades for water or sugar to
travel from the roots of a redwood to the
leaves via diffusion
Instead, bulk flow creates pressure which
drives fluids
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Root hairs increase surface area for
absorption
Mychorrhizae are structures made from
symbiotic relationships between roots and
fungi
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The endodermis is the innermost layer of root
tissue
Located here is the Casparian strip, a waxy
layer that is impervious to water and minerals
This sets up a selectively permeable
membrane; prevents leakage and water loss
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Plants lose water through
their leaves via
transpiration
Just like you suck water
up a straw, water is
pulled up xylem as it
exits the leaves
Cohesion and adhesion
allow these sticky water
molecules to be pulled up
xylem
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When stomata are open for gas exchange, they also
cause water loss (90% of all water loss)
In general, they are open during the day and closed
at night
Stomata are triggered by light; CO2 depletion; and
circadian rhythms
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Sugar is
transported in
phloem, which is
called translocation
Sugar travels both
up and down a
plant’s tubes
Sugar moves from
areas of high
concentration to
areas of low
concentration
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