2-9-11 Growth

2-9-11 Growth - Q1?
Most
animal
growth
is
limited

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Q1?
Most
animal
growth
is
limited to

embryonic
or
juvenile
phase. Same
for
plants? Plant
Primary
and Secondary
Growth a. Yes b. No 1 Shoot tip (shoot apical meristem and young leaves) Q2?
For
plants,
meristems
allow plants
to
grow
or
extend
in a. b. c. d. 2 Why
care? ‐Primary
growth
from apical
meristems produces
short‐lived expendable
surface
areas for
resource
acquisi?on Axillary bud (leaves
and
roots
hairs) meristem and
other
structures Length Width Length
and
width Neither
length
nor
width Vascular Lateral cambium meristems Cork (in
plants
with cambium secondary growth) Root apical meristems 3 Apical
meristems increasing
length
of plant
parts,

i.e. “reaching”
growth (Assigned
reading: Essence
of
“Plantness”) New
leaves
and
stem produced
by
growth
at shoot
apical
meristem Leaf
forma?on begins
before much
cell elonga?on.

Why? 4 Q3?
What
is
the
adapGve
advantage
of producing
pairs
of
leaves
on
different
sides
of a
stem? Young
leaf: out
of
plane Short internodes 5 a. b. c. d. e. Maximize
transpiraGonal
water
loss Minimize
transpiraGonal
water
loss Maximize
light
capture Minimize
light
capture Maximize
protecGon 6 Cortex Vascular cylinder Lateral
branching
roots
arise
from
de‐differen?ated parenchyma
near
xylem Epidermis Key to labels Root hair Dermal Zone of differentiation Ground Why
no
root
hairs closer
to
root
?p? Vascular Zone of elongation Apical meristem Root cap Note:
Root
hairs
do
NOT
grow into
mul6cellular
lateral
roots, these
are
en6rely
different structures Zone of cell division 7 Secondary
Growth Q4?
Primary
growth
from
apical
meristems produces
cells
with a. b. c. d. Study
ques6on:
Why
do
new roots
arise
near
vascular
6ssue? 8 Fig. 35-13 100 µm Adds
girth
or
thickness Stems
and
Roots Woody
plants
only • • • Primary
cell
walls Secondary
cell
walls Both Neither 9 Shoot tip (shoot apical meristem and young leaves) Axillary bud meristem 10 Secondary
Growth:

produced
from
secondary
meristems Secondary
(lateral)
 








meristems






 Vascular cambium 2 Lateral meristems Cork (in
plants
with cambium Secondary
(2o)
?ssues Vascular
cambium Cork
cambium Func?on? Secondary
xylem
(wood) Secondary
phloem Cork
or
periderm
(part Bark) secondary
growth, i.e.
woody
plants) • Note:
primary
and
secondary
growth
occur
at
same
?me but
in
different
places Root apical meristems 11 12 Secondary
Vascular
Tissue Three
years growth
in winter
twig Where
is
the
vascular
cambium
and
the
?ssues
it
produces? One
year old
stem Primary
xylem Primary
phloem Two
year old
stem 13 secondary
xylem vascular
cambium secondary
phloem 14 Fig
35.11 How
does
vascular
cambium
form
2o
vascular
?ssue? Cambium
‐
con?nually
displaced
outward Cambial
ini?al
can
divide
to
form: • 2
cambial
ini?als • • Vascular
cambium
forms between
primary
xylem
and phloem ‐Where
is
newest
?ssue produced
by
this
cambium during
the
next
year? ‐Where
is
vascular
cambium this
year
compared
to
last? 1
cambial
ini?al
and
1
2o 
xylem
cell 1
cambial
ini?al
and
1
2o 
phloem
cell More
xylem
than
phloem
produced 2o
xylem
cells: • • • Tracheids Vessel
elements Fibers 2o
phloem
cells: ‐Note:
cork
cambium,
we
will come
back
to
that • • • • 15 The
real
thing.

 Sieve‐tube
elements Companion
cells Parenchyma fibers 16 Q5?
Which
wood was
most
recently produced? Secondary
phloem 1 2 vascular
cambium a. b. c. d. Secondary
xylem 17 1 2 3 4 3 4 18 Dendrochronology

‐
study
of
tree
ring
growth
pa]erns In
temperate
Regions: Spring
wood
xylem: • • • rela?vely
large
diameter thinner
walls Maximum
water
delivery
capacity More
secondary
?ssue produced
in
warm
years
and less
in
cool
years. Fall
wood
xylem: • • • smaller
diameter very
thick
walls. More
support. Graph
showing
ring‐width
for
a
series
of
cores taken
from
preserved
Mongolian
conifers 




Why
is
this
adap6ve? Cambium
dormant
during
winter Study
ques6ons: How
old
is
this
stem? Where
is
the
oldest
wood? Study
ques6on:
What
do
these tree
rings
tell
us
about
climate change
in
Mongolia? Also:
can
be
used
to
date archeological
ar?facts 19 20 Sapwood: youngest 2o xylem layers Active in transport • • Heartwood x ylem: Oldest 2o xylem layers Not active in transport Darker due to resins and other compounds that protect against fungi and wood-boring insects • • • • Bristlecone
pines:
"Methuselah"
is
currently
~4,770
years
old • An
older
tree
“Prometheus”
(4862
years
old)
was
cut
down
by a
PhD
student
because
his
corer
broke
inside,
subsequent outcry
lead
to
preserva?on
of
remaining
trees 21 • The
Brazilian rosewood
that
goes into
your
dream acous?c
guitar • The
oak
flooring
that
you
want for
your
house sapwood heartwood 22 Secondary Dermal Tissue Where
is
the
cork
cambium
and
what
?ssues
does
it

produce? Cork
cambium
‐
forms
from parenchyma
in
cortex ALL
 XYLEM! • The
redwood deck
that
you want
to
build 23 24 The real thing. Study
ques?ons: ‐Are
trees
with
periderm
splihng
and falling
off

sick? ‐What
happens
to
the
cork
cambium? cork cork cambium phelloderm periderm bark 2o phloem 25 26 Commercial
cork Cork
oak:
Quercus
suber • • Na?ve
to
Mediterranean
(Spain,
Portugal) Outer
~50%
of
periderm
removed
every 10
years Q
6?
If
the
cuZng
takes
off
the
bark
(not
just the
periderm),
what
happens
to
the
tree a. b. c. d. 27 Q
7?
If
you
nail
a
bluebird
house
to
a
5
year
old pine
tree
at
10’
height,
how
far
off
the
ground will
the
birdhouse
be
a`er
10
more
years? a. b. c. d. e. 5’ 10’ 15’ 20’ 30’ 29 Nothing Greater
suscepGbility
to
disease Slower
growth Death 28 ...
View Full Document

Ask a homework question - tutors are online