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An
underdeveloped
stem/leaf/flower
Stem Structure
Bud
So if Nodes are
crucial “organs”
of the plant,
then the
internodes are
like the blood
vessels that
carry water
from node to
node.
Stem
Is the stalk that
Petriole attaches the leaf to
the stem.
Internode Space between
nodes.
Point on a stem
Node
where the buds,
leaves and branching
twigs split.
Leaf Structure
Waxy layer that protects against water loss,
insects and UV light
Additional protection.
Large number of chloroplast (to Transports
carry out photosynthesis.
water to the
leaves
Lightly packed chloroplasts,
allows for gas exchange.
O and CO2
exchange with
environment.
Controls the
open/closing
of stoma.
Carries the
products of
photosynthesi
s to the rest of
the plant.
Xylem Cells
Dead Cells
Thickened cellulose,
lignified secondary
walls
Strengthens cell walls
Waterproofs plant
Protects against
pathogens
Tapered to form
continuous
column
Most modern plants
Allows water to
mover laterally
Ancient plants
Stomata Operations
Open/close due to
cell turgor of
guard cell
Guard Cells bulge
to outside, when
take in water 
opens
Blue light triggers
ATP powered
pumps
Causes K+ to
move into guard
cells
Higher solute =
osmosis
Video
Cell wall
thickness uneven
Loss water, cells
sage towards each
other.
K+
K+ is forced out
byabsisic acid
(plant hormone)
Produced in root
during water
deficiency
Other Regulators
of open/close:
CO2 levels
circadian
rhythms
Cells sag due to
water loss (close)
Transpiration
Cohesion-Tension Theory
2. Water lost by transpiration is
replaced by water from xylem
1. Water moves down concentration
gradient (out of plant) into
atmosphere, which has low water
concentration.
3. Vessel water column is maintained
by cohesion/adhesion
Cohesion: H bond to form water.
Adhesion: water bond to sides of
vessels.
4. Water is pulled from root cortex
into xylem cells
Cohesion and Adhesion maintain
columns under the tension created by
transpiration.
5. Water is pulled from the soil into the
roots. Created from tension created by
transpiration.
Root Structure
Fully differentiated
 functional cells
Root Hairs: increase surface
area = more absorption of
water/minerals x3
Enlarging cells
(G1 phase)
Start differentiating
Zone of cell
division (M phase)
‘Stem’ cells –
undifferentiated cells
Protects apical meristem
Cross Section of Root
Water movement: due to osmosis
(higher solute concentration inside root)
Root Hair
Epidermis
Endodermis
Xylem
Vascular
Bundle
Pericycle
Phloem
Cortex
Mineral Ion Movement
Fungal Hyphae: symbiotic relationship
Increases surface area for absorption
Active Transport: high
concentration of solute in root
Need more or ion cannot
pass lipid bilayer 
hypertonic situation
Diffusion of mineral ions by
mass flow of water
Passively flow due to
low solute
concentration in root
Movement within roots
All particles need to go symplastic at
endodermis to get to xylem
Water
and
Minerals
Movement between cell walls
Movement within cells – water/minerals
pass through plasmodesmata
Factors that affect transpiration
Increase evaporation
Reduces difference in
water concentration
gradient
Removes humidity from
stomata
Less soil water, water
stream stopped at roots,
stomata close
Increase kinetic
energy - evaporation
Cause guard cells
to lose turgor –
close stomata
Xerophytes
thickened
Crypt/pit –
increases humidity
Reduced
number
Trap water vapor,
increases humidity
Decreases surface
area for transpiration
Go dormant in dry months
Succulents – fleshy
stems
Alternative photosynthetic
pathway
CAM: stomata open at
night
C4: rapid uptake of
CO2
Halophytes: high levels of salinity
Sunken stomata
Leaf surface area reduced
Succulents: dilute salt concentration
Compartmentalize Na+ and Cl- in
vacuoles
Prevents salt toxicity
Salt glands: secrete salt