Chapter 25
Nutrition and Transport in Flowering
Plants
Read chapter 25 in textbook
(remember to look at book website)
Read 207-210 in Cliffs AP Book
Chapter 25 Overview
• Topics
– Plant Nutrition and Soil
– Uptake of water and minerals
– Transport Mechanisms in Plants
He planted a 5 lb. willow tree in a pot containing 200 lbs. of soil.
He watered the tree regularly for 5 years and watched it grow.
Ch 25 Nutrition and Transport in Plants
At the end of 5 years he weighed
the plant
and the soil.
25.1 Plant
Nutrition
andWhat
Soil did
he expect to find? What were his results?
• In the early 1600’s a man
named John Baptiste Van
His results:
Tree weighed
Helmont
set170
up lbs.
an
Pot and soil weighed
a few
ounces less than 200 lbs.
experiment
to prove
plants
He concluded
that the
increase in weight (165#) was due to water.
were “soil
eaters”
Was he correct?
– What was his experiment?
Whatdo
didneed
he think
hebut also CO2 and sunlight to
Sort of:--– plants
water,
discovered? which are the main organic components of
produce carbohydrates
plants. Also they absorb minerals from the soil.
Ch 25 Nutrition and Transport in Plants
25.1 Plant Nutrition and Soil
• Essential Inorganic
Nutrients
– Can you think of a method
of growing plants that might
help determine which
nutrients are essential?
Hydroponics
Ch 25 Nutrition and Transport in Plants
25.1 Plant Nutrition and Soil
• Essential Nutrients
– 96% of plant dry weight made up of C, H, O
– Macronutrients and micronutrients needed from environment.
Examples of macronutrients:
•
•
•
•
•
•
N - for nucleic acid formation
K – cofactor for enzymes
Ca – regulator and stability of cell walls
P – nucleic acids, ATP
Mg – part of chlorophyll
S – part of amino acids and coenzymes
Ch 25 Nutrition and Transport in Plants
25.1 Plant Nutrition and Soil
Ch 25 Nutrition and Transport in Plants
25.1 Plant Nutrition and Soil
• Soil formation
– Involves interplay of:
• Physical
• Chemical and
• Biological forces
Ch 25 Nutrition and Transport in Plants
25.1 Plant Nutrition and Soil
• Soil – it’s not just dirt!
– Terrestrial organisms (which eat plants, or use O2) rely on soil to
provide plants with everything they need except carbon dioxide (where
Moss in foreground,
is that from?).
female spore of
– Soil
formation
liverwort.
Male
spore of involves physical, chemical and biological factors.
–liverwort.
Takes a long time – about 15 yr to produce 1 cm of soil.
– Soil
• Mixture of soil particles of varying sizes (lg sandmed siltsm clay),
• Decaying organic material (humus),
• Living organisms (lichens and mosses) (moles, badgers, earthworms,
millipedes)(microorganisms – protozoa, bacteria fungi), and
• Air and water
Left - Lichens= Fungus and algae
growing mutualistically.
http://www.ontariowildflower.com/mo
ss.htm
Right - Humus
Sand, Silt, and Clay http://generalhorticulture.tamu.edu/h202/labs/lab7/mineral-particles/clay.html
Ch 25 Nutrition and Transport in Plants
25.1 Plant Nutrition and Soil
• Soil particles
– Clay particles
• neg charged so help hold on to
positive ions – keeps them from
being washed away
• Acid rain can displace these
positive ions
• NO3- is neg, so clay does not
hold well, so N content of clay
soil is low. N fixing bacteria can
help this
– Loam is 1/3 sand, 1/3 silt, 1/3
clay – good balance
Root nodules (N fixing
bacteria) on pea roots.
Ch 25 Nutrition and Transport in Plants
25.2 Water and Mineral Uptake
•
Uptake of water and minerals
– Water is taken up into the root cells by
osmosis.
– Minerals are taken into the root cells
against their concentration gradient by
active transport. Plants are able to
concentrate the minerals. Uses ATP.
– water and minerals that are in soil or root
hair cell, can get to xylem via:
• Pathway A (root)between cells (water)actually travels through cell walls, not
between cells. Apoplastic route.
• Pathway B (root hair)through cells (water
or minerals). Symplastic route.
– At Casparian (subrin and lignin) strip
water and minerals gets routed into xylem
(water passively – minerals actively) by
going through endodermal cells.
Ch 25 Nutrition and Transport in Plants
25.2 Water and Mineral Uptake
•
Uptake of water and minerals
– Minerals taken up in ionic form.
– Plasma membrane has a slight charge –
makes it difficult for ions to pass through
– Takes energy – ATP supplies energy to run H
pumps (proton pump).
– Chemiosmosis and electrochemical gradients
set up.
• H pumped out of cell – creates more positive
charge outside cell
• K ions (and other pos ions)are repelled by
positive charge and move into cell
• H ions flow down conc gradient into cell,
bringing neg charged particles with them
– Once the minerals are in the extravascular
space, they are taken into the xylem (which is
dead) passively by diffusion.
•1.
•2.
•4.
•5.
Water
Minerals
Entry
of
transport
canthe
diffuse
also
minerals
take
inward
pumps
a pathway
raises
minerals
via the
the
between
into the
cells
•3. Active
Pericycle
cells
actively
pump
minerals
out
concentration
until
cytoplasm
it reaches
of root
of
the
minerals
hair
Casparian
cells.
Water
strip.
thebyextracellular
follows
by
plasmodesmota.
Water
follows
osmosis.
of their
cytoplasm
into
theinextracellular
space
space,
osmosis.
they
diffuse intofollows
the dead
cells.
aroundsothe
xylem.Water
byxylem
osmosis.
Water follows by osmosis.
Ch 25 Nutrition and Transport in Plants
25.2 Water and Mineral Uptake
Ch 25 Nutrition and Transport in Plants
Without mycorrhiza
With mycorrhiza
25.2 Water and Mineral Uptake
• Adaptations of roots for mineral uptake
– Two symbiotic relationships
• Rhizobium bacteria fix atmospheric Nitrogen(N2) to ammonium (NH4) and
nitrites and nitrates
– Root nodules in legumes (beans)
– Bacteria get carbs from plant, plant gets N
• Mycorrhiza fungi
– Associated with almost all plant roots
– Plants get greatly increased absorptive surface and fungus breaks down organic matter
for plant to absorb
– Fungus gets sugars and amino acids from plant
– Epiphytes (ex.: orchids)
• “Air roots” – live on other plants but not parasitic, don’t need soil
– Parasitic plants (ex. - dodder, broomrape,
pinedrops)
Mycorrhizal
root system washed carefully from
coarse sand to reveal the intact network with
• Invade
cells of host plant
Sundew
externalsundew)
hyphae (arrow) with spores (S) produced
– Carnivorous plants (ex. - Venus flytrap,
• Can digest insects
by Glomus mosseae.
Ch 25 Nutrition and Transport in Plants
25.2 Water and Mineral Uptake
Dodder plant (yellow
because it has no
chlorophyll)
parasitizing a tulip
plant.
Ch 25 Nutrition and Transport in Plants
25.2 Water and Mineral Uptake
Epiphytes
growing in a tree
Proton Pump Animation
Root Nodule Formation
Ch 25 Nutrition and Transport in Plants
25.3 Transport Mechanisms in Plants
• Two main transport
mechanisms
– Xylem
• transports water and
minerals from roots to
leaves (only moves in one
direction)
– Phloem
• Transport organic nutrients
to cells that need
them(either direction).
Ch 25 Nutrition and Transport in Plants
25.3 Transport Mechanisms in Plants
• Xylem
– Tracheids
• Narrower than vessel
elements
• Joined end to end
• Pitted end walls
– Vessel elements
• Larger - wider
• Joined end to end
• Form a continuous
hollow tube
Vessel elements – shorter and
wider, water passes freely from
one to the next through a
perforation (area with no cell
walls). Water movement faster
than in tracheids.
Tracheids – narrower with tapered ends.
Water passes through pits in tapered parts.
• Vessel element SEM
www.DennisKunkel.com
Ch 25 Nutrition and Transport in Plants
25.3 Transport Mechanisms in Plants
• Phloem
– Sieve tube elements(cells)
• Form a conducting tube
• Contain cytoplasm, but
have no nucleus
• On ends are sieve plates
• Elements connected by
plasmodesmata
– Companion cells
• Helper cells
• Supply proteins to sieve
cells
From http://www.estrellamountain.edu/faculty/farabee/biobk/BioBookPLANTANAT.html
Seive tube elements – have sieve plates at their ends –
area with pores where cytoplasm of the cells connects.
Cytoplasm communicates through plasmodesmata.
Companion cells – parenchymal cells adjacent to
sieve tube elements. Physiologically support the
nuclei free sieve tube elements.
Ch 37 Nutrition and Transport in Plants
37.3 Transport Mechanisms in Plants
• Water transport (xylem)
– Driven primarily by transpiration
– Water entering xylem is
• pushed by root pressure
– Mostly at night
– Water pulled in by osmosis –
pushes water up xylem
– Can only raise the water up a
small distance
– Can cause guttation (stomates are
closed)
• pulled by transpiration
– Relies on cohesion, adhesion and
evaporation – pulls water up
xylem
– At least 90% of all water taken in
by roots is lost by transpiration
– Relies on stomates being open
Transpiration animations:
..\..\Biology\Biology Clipart Movies Animations
Sounds\Biology movies\transpiration tree animation QT
40sec.mov
Ch 25 Nutrition and Transport in Plants
25.3 Transport Mechanisms in Plants
• Water transport tutorial (30 sec)
– ..\..\Biology\Biology Clipart Movies Animations
Sounds\Biology tutorials\plant water movement.dir
Ch 25 Nutrition and Transport in Plants
25.3 Transport Mechanisms in Plants
• Opening and closing of
stomates
– Guard cells on either side of
opening (stomate) can
actively transport K in and
out.
– K ion transported in 
increased osmotic pressure 
water pulled in  guard cells
swell and bend to open
stomate
– Proton pump fueled by ATP
hydrolysis pumps H ions out
and sets up electrochemical
gradient that favors K moving
into cell.
Ch 25 Nutrition and Transport in Plants
25.3 Transport Mechanisms in Plants
• Animation plant leaf stomata
– ..\..\Biology\Biology Clipart Movies Animations Sounds\Biology
tutorials\stomata plm2s3b[1].ram
http://www.pbrc.hawaii.edu/bemf/microangela/stomata7.htm
www.botany.uwc.ac.za/.../ leaves/insideleaf2.htm
Ch 25 Nutrition and Transport in Plants
25.3 Transport Mechanisms
inmovie
Plants
Stomate
(48 sec):
..\..\Biology\Biology Clipart Movies Animations
Sounds\Biology movies\stomatal movement
movie.mov
• Factors that regulate K concentrations in guard cells; therefore stomate
Stomata and water flow animation
opening and closing
– Light reception
..\..\Biology\Biology Clipart Movies Animations
Sounds\Biology movies\Stomata[1].mov
• Open in light (so can do photosynthesis), close in dark (to conserve water when
photosynthesis can’t occur)
– Carbon dioxide concentrations
• Low CO2 (in leaf) – open
• High CO2 - close
– Water
• Leaf loses water starts to wilt  releases abscisic acid inhibits K transport close
– Heat
• may cause increased cell resp, leading to increased CO2 leading to closing stomates.
May be a combination of lack of water and too much heat.
– Circadian rhythm
• Even if plant in dark 24 hrs, stomates still open and close
Ch 25 Nutrition and Transport in Plants
25.3 Transport Mechanisms in Plants
• Stomata control summary
– Factors that open stomata
• Red light and Blue light (from sunlight) that chloroplasts absorb
• Low internal CO2 concentration (high level of photosynthesis)
• Circadian rhythm
– Factors that close stomata
•
•
•
•
•
Dark (except CAM plants – stomata open at night)
Abscisic acid (hormone released when plant wilts)
High internal CO2 concentrations (if photosynthesis stops)
Circadian rhythm
Lack of water
Ch 25 Nutrition and Transport in Plants
25.3 Transport Mechanisms in Plants
• Organic Nutrient Transport
(Phloem)
– Experiments with girdling, aphids,
and radioactive 14 C showed
phloem transports sugars
– Pressure flow model
• Source (photosynthetic cells) and
sink (cells that need energy)
• Positive pressure drives the sap
(can go up or down)
• Sucrose actively transported along
with H+ by proton pump, water
follows by osmosis
• Chemiosmotic mechanism
Pressure Flow ModelFormation
Water Transport in Xylem Formation
Water Transport in Phloem Formation
Ch 25 Nutrition and Transport in Plants
25.3 Transport Mechanisms in Plants
– Animation Pressure Flow Model
• Plant organic nutrients movement
– ..\..\Biology\Biology Clipart Movies Animations Sounds\Biology
tutorials\plant organic nutrient movement.dir
The End
Ginko plant growing animation
http://www.indiana.edu/~oso/animations/An12.html