Lecture 2-Plant physiology Flashcards
vascular bundle in leaves
between sclerenchyma bundles, enclosed by living cylinder of cells
Growing upwards, what came first?
lignified tissue xylem
Plants that undergo secondary growth
some annuals like sunflowers, all trees and vines
Primary to secondary growth
zone of division in region between vascular bundles called VASCULAR CAMBIUM. inside forms secondary xylem, outside forms secondary phloem. epidermis ruptured and replaced by cork and periderm formed by cork cambium
Annual plant prim. or sec.?
Usually just primary body (derived from embryo)
Perennial plants prim. or sec.?
P and S body.
phloem replaced every year (prev. is crushed) S
Xylem replaced every year (prev. stays in place)S
Leaves replaced every year P
Three ways of water movements
inside living cells-symplastically
between cells-apoplastically
into cells (sym) then out into apo. only to re-enter cell-transmembrane pathway
How does water enter root?
root hairs and root tips
Minerals that are accepted? rejected?
Ca accepted. Na Ni rejected
Can water move apoplastically past endodermis?
No, waxy water-repellant layer (Casparian Strip)
Bulk flow
water movement, driven by evaporation
Cohesion-adhesion theory
water molecules pull each other along using co and adhesion
Transpiration
water loss by aerial organs
Stomates
opening and closing can regulate effect of evaporation, causes 95% of water loss
Stomate opens because
K+ pumped in, water follows, guard cells balloon
Stomate closes because
k+ pumped out, water follows, guard cells lose h2o and shrink
Abscisic acid
hormone produced in roots b/c of water deficiency, causes closing of stomata
Easy water movement through plant?
apo is easiest, symplast is easy too
How does water get past lipid bilayer surrounding living cells?
protons establish membrane potential
co-transport of neutral solutes w/ protons.
co-transport of ions (nitrates) with protons
Aquaporins
bidirectional channel proteins.
single file transport of water (10 at a time)
3 billion/s
decrease rate if cell more acidic and increase in cellular Ca ion concentrations
solute potential
directly proportional to molarity of solution. aka osmotic potential
pressure potential
physical pressure on soultion
Turgor pressure
pressure exerted by plasma membrane against cell wall and cell wall against protoplast
protoplast
living part of cell including plasma membrane
