controlled by guard cells flaccid little water limp turgid fill with water bend
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Controlled by guard cells
Flaccid Little water Limp
Turgid Fill with water Bend
http://academic.kellogg.edu/herbrandsonc/bio111/animations/0021.swf
Triggered by blue light Yellow pigments located in membrane
(?)
Activates proton pump H+ out, creates electrochemical
gradient
K+ diffuses in through ion channels, Cl- follows
K+, Cl- accumulate in vacuoles, water moves in
K+ concentration in guard cells decrease during day
Sucrose increases, maintains osmotic pressure
As sucrose concentration decreases, water leaves
Pores close
Transpiration 99% of water plants take in is lost by evaporation Open stomata
Rate of Transpiration affected by: Humidity Temperature Wind
Guttation Liquid water forced out when transpiration
negligible
Conifers lose needles year-round
Deciduous trees Survive low temp of
winter Water uptake inhibited Prevents continuous
water loss by transpiration
Controlled by hormones: Ethylene
Essential organic compounds & minerals move to other parts of plant for storage
Chlorophyll breaks down, other pigments seen
Cork forms protective layer on stem side of abscission zone of petiole
Enzymes dissolve middle lamella in abscission zone of petiole
Leaf detaches in breeze
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