Transcript lect9-30CUT

Secondary Growth
Secondary Growth
• Two types of growth
• Primary growth: up and
down. Generated by apical
meristems. Form _________
tissues
• Secondary growth: growth in
girth. Generated by lateral
(secondary meristems). Form
__________ tissues.
• All plants do primary growth
• Woody plants do __________
growth
Secondary Growth
• Lateral meristems
– 1) ______________: makes
new phloem and xylem
– Called ________ phloem and
xylem tissues (vs. primary
phloem and xylem made
directly from procambium)
– Function: xylem takes water
+ minerals to leaves, phloem
takes sugars to roots
Secondary Growth
• Lateral meristems
– 2) ___________: makes new
cell type, cork cell. Cork cells
with primary wall
impregnated with waxy
material (_______). Dead at
maturity. Forms waterproof
layer on outside of body to
replace epidermis.
– _________: Tissue composed
of cork cells and made by
cork cambium. Also is a
secondary tissue.
Secondary Growth
• Stem cross section
Secondary Growth
• Vascular bundles contain __________________
• Located between primary xylem and phloem
• Meristematic: can still do _______________
Secondary Growth
• Residual procambium cells start to divide
• Produce new cells ______________
Secondary Growth
• Parenchyma cells between bundles also start to divide
• Together form solid ring of cells, all dividing laterally
• This is __________________
Secondary Growth
• Vascular cambium makes secondary xylem on
__________, secondary phloem on __________
• Note how cambium moves outward over time
Secondary Growth
• Note arrangement of primary phloem and secondary
phloem, primary xylem and secondary xylem
Secondary Growth
• Secondary xylem may contain:
–
–
–
–
1) Vessel elements
2) Tracheids
3) ____________
4) Fibers
• Secondary phloem may contain:
–
–
–
–
1) Sieve tube elements
2) Companion cells
3) Parenchyma
4) ___________
Secondary Growth
• Two
Secondary Growth
• Later secondary growth
Secondary Growth
• First cork cambium: Forms under ___________
Secondary Growth
• Cork cambium: Makes files of cork cells to
outside. Forms first __________. Epidermis
cut off from rest of stem and dies.
Secondary Growth
• Problem: cork cells are
dead at maturity. Cork
layer cannot _________ as
vascular cambium
continues to grow.
• Solution: form new ______
______ in cortex under old
one
• After time, several
__________ build up
(yellow lines). Newest
(inner) one cuts off water
to layers beyond it and they
_______.
Secondary Growth
• Periderm replaces epidermis. How get _______
into stem?
Secondary Growth
• Lenticels: Loosely packed __________. Allow
oxygen to diffuse into stem to support living
cells there.
Secondary Growth
• Note ____ made by
vascular cambium:
Form ________
transport system
(often parenchyma
cells)
• In phloem: phloem
ray
• In xylem: xylem
ray (wood ray)
Secondary Growth
• In temperate zone, cambium activity varies
between _____ and ______ in growing season
• Spring: big cells (_______ wood).
• Summer: small cells (_______ wood).
• Form growth ring (tree ring): one season’s growth
• Ex, pine (mostly tracheids)
Secondary Growth
• Ex, oak (note vessels, thick-walled _________)
Secondary Growth
• Young tree section: Note rays here (phloem and
xylem)
• Also note growth rings: early and late wood
• How old was this stem when cut?
Secondary Growth
• In older tree: wood
is secondary xylem
• Heartwood: old
non-functional
xylem
• ________: younger
often functional
xylem
Secondary Growth
• Bark: From vascular
cambium outward
• ___________: From
current cork
cambium outward
(all is dead)
• __________: From
vascular cambium to
current cork
cambium. Contains
functional secondary
phloem
Secondary Growth
• Removing inner bark
is deadly: girdling
tree often will kill it
• Why? Roots ______
• Why? No ________
from leaves.
Secondary Growth
• Flow chart, showing how primary and
secondary tissues develop in stem
Secondary Growth
• Note that roots of woody plants also do secondary
growth
• Vascular cambium forms from __________
• First cork cambium forms in _____________.
Secondary Growth
• So outer cortex and epidermis are sloughed off
and lost
Uses of Growth Rings
• 1) Fire frequency
• Break in bark (_________)
allows fire to burn through
vascular cambium into
wood
• Leaves burned layer
• If tree survives, can have
record of fires in wood.
Ponderosa pine, WY
Uses of Growth Rings
• 1) Fire frequency
• Helpful information
when trying to
determine “natural”
frequency of fires for
managing forests.
Uses of Growth Rings
• 2) Climate patterns (___________________)
• Width of rings can indicate growth conditions
for tree (rainfall, etc.)
• Can reconstruct climate information
• Oldest reconstructions go back 8,000 yr B.C.
Uses of Growth Rings
• 2) Climate patterns
• Oldest
reconstructions from
bristlecone pine
wood go back as far
as ________ yr B.C.
Plant nutrition
• Plants sophisticated: All they need is CO2,
H2O, ________________
• Can make all amino acids, nucleic acids,
carbohydrates, vitamins they need
• Contrast __________: need essential amino
acids, fatty acids, carbohydrates, vitamins,
etc.
Plant nutrition
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•
•
•
•
Plants need ____ essential elements
Macronutrients: make up >_____% of plant
C, H, O, P, K, N, S, Ca, Mg
“See hopkins car is an MG”
“C HOPKiNS Car is an Mg”
Of these, >____% plant dry weight is each of
C,H,O,N,K (Chonk!)
Plant nutrition
• Plants need ____ essential elements
• Micronutrients: make up <_____% of plant
dry weight. Need in tiny amounts!
• Fe, Mo, B, Cu, Mn, Zn, Cl
• “A festive mob comes in ___________”
• “a Festive MoB CuMnZn CL___________”
Plant nutrition
• All elements come to plant mostly from _____
• Except for C and some O, which come from
atmosphere (CO2)
• What usually limits plant growth?
• ______! Why?
• Lots needed for proteins, nucleic acids, etc.
• Easily washed from soil
Plant nutrition
• Nitrogen: lots in atmosphere (______% N2)
• But plants can’t ______ that
• Nitrogen fixation: bacteria use N2 to form
NH3 (ammonia) or NO3- (nitrate)
Plant nutrition
• Special ways to get N:
– _____________: Leaves modified to trap and digest
animals. Mainly to supplement N (bog soils low in N)
QuickTi me™ a nd a Cinep ak decompre ssor are n eede d to see thi s pi ctu re.
Plant nutrition
• Special ways to get N:
– ______________ bacteria: many legume plants form
nodules on roots. N-fixing bacteria inhabit, obtain
____________, provide plant with N
Kingdom
Animalia
Kingdom Animalia
• About 1.2 million described species
• Approx. ____% are arthropods (Phylum
Arthropoda), most of those are insects (Class
Insecta)
• Contains about _______ phyla, most of which
are marine (where life ________)
Kingdom Animalia
• Evolved from Protista
Major features of animals
• 1) _______________
• 2) _______________
• 3) Lack _____________. Most have tissues:
organized groups of cells specialized to perform
specific functions
• 4) Move in rapid and complex ways. Flexible
cells, presence of nerves and muscles.
• 5) ___________ meiosis. Make eggs and sperm.
Major features of animals
• 6) Embryo stage.
– Morula: Solid ball of cells
– Becomes a ______________: Hollow ball of cells
– Then becomes Gastrula: Hollow ball with a sac at
one end (called _______________)