I. Nutrients from soil and air B. 95% of a plants dry weight is
organic (built mainly from CO 2 ) - plants are predominantly built
from the air C. Sugar Chapters 32: Plant Nutrition and Transport
Fig. 32.1A - carbon and oxygen from CO 2 - hydrogen from water -
Two fates - cellular respiration or biosynthesis A. Plants need to
make everything (organic) from scratch (inorganic) (Some) Slide 2
I. Nutrients from soil and air Chapters 32: Plant Nutrition and
Transport Fig. 32.1A D. Nitrogen, phosphorus, Mg ++, etc from soil
- used in combination with glucose to make hormones, ATP, coenzymes
(chlorophyll), nucleotides, amino acids, etc i. nitrogen ii.
Magnesium (Mg ++ ) - part of chlorophyll iii. phosphorus - ATP,
nucleic acids, phospholipids, etc (Some) Slide 3 II. PM of roots
control solute uptake Chapters 32: Plant Nutrition and Transport A.
Root hairs provide high surface area - Casparian strip Fig. 32.2 -
Intracellular route vs. Extracellular route C. Epidermis -->
cortex --> endodermis --> xylem - waxy belt through walls of
endoderm - stops solution from entering xylem via cell walls D.
Endodermal membrane is highly selective (gatekeeper -> cant get
into xylem without being aloud through) B. Must be dissolved in
solution to enter Slide 4 III. Getting xylem sap up to the shoot
system Chapters 32: Plant Nutrition and Transport A. Water/minerals
(xylem sap) must somehow get up xylem vessel B. How does it do this
against gravity??? - minor push from roots actively pumping ions
into xylem (water follows by osmosis) i. Root pressure - works over
a few meters - not enough for taller trees, and many trees (i.e.
giant sequoia) produce NO root pressure Slide 5 III. Getting xylem
sap up to the shoot system Chapters 32: Plant Nutrition and
Transport A. Water/minerals (xylem sap) must somehow get up xylem
vessel B. How does it do this against gravity??? Fig. 32.3 ii.
Transpiration - loss of water from leaves (stomata) pull xylem sap
upward a. cohesion (water hydrogen- bonding to other waters): makes
the xylem sap like a continuous string b. Adhesion (water sticking
to other molecules): sticks to cellulose walls of xylem - Two
properties of water that make this possible: Slide 6 III. Getting
xylem sap up to the shoot system Chapters 32: Plant Nutrition and
Transport A. Water/minerals (xylem sap) must somehow get up xylem
vessel B. How does it do this against gravity??? Fig. 32.3 ii.
Transpiration - water molecule at end of chain in leaf is heated by
solar energy - This molecule diffuses out of the stomata and
evaporates - As it does this, it pulls on the neighboring waters
(cohesion), the neighbors pull on their neighbors and so on all the
way to the roots (Without the suns KE, the water in the leaf would
remain stuck to its neighbors - no pulling force, no transpiration)
Slide 7 III. Getting xylem sap up to the shoot system Chapters 32:
Plant Nutrition and Transport A. Water/minerals (xylem sap) must
somehow get up xylem vessel B. How does it do this against
gravity??? Fig. 32.3 ii. Transpiration - What about adhesion? -
adhesion counters downward pull of gravity by grabbing walls of
xylem - holds water in xylem when transpiration is not occurring
(at night) Slide 8 IV. Guard cells control transpiration Chapters
32: Plant Nutrition and Transport A. Transpiration works for and
against plants i. Water loss - plant needs to lose water in order
to get minerals - average maple tree loses 200L per hour during
summer - not a problem only if there is enough water in soil A
wilting plant caused by water loss under dry conditions Slide 9 IV.
Guard cells control transpiration Chapters 32: Plant Nutrition and
Transport B Stomata i. Each has a pair of guard cells - change
shape to control opening - open during day when photosynthesis
rates are high (need CO 2 ) - closed at night to save water Guard
cells of stomata Slide 10 IV. Guard cells control transpiration
Chapters 32: Plant Nutrition and Transport B Stomata ii. How do
guard cells change shape to regulate open/closed state? Fig. 32.4
1. opening stomata - guard cells ACTIVELY take up K + - water
follows by osmosis - causes swelling and high turgor pressure
(pressure of cells contents against cell wall) - causes cells to
bend away from each other due to arrangement of cellulose fibers:
Slide 11 IV. Guard cells control transpiration Chapters 32: Plant
Nutrition and Transport B Stomata ii. How do guard cells change
shape to regulate open/closed state? Fig. 32.4 1. opening stomata -
What stimulates guard cells to take up K + ? a. sunlight, low CO 2,
circadian rhythm (biological clock) Slide 12 IV. Guard cells
control transpiration Chapters 32: Plant Nutrition and Transport B
Stomata ii. How do guard cells change shape to regulate open/closed
state? Fig. 32.4 2. Closed stomata - actively pump out K+ - water
follows passively (osmosis) - cells sag and stomata close: Slide 13
IV. Guard cells control transpiration Chapters 32: Plant Nutrition
and Transport B Stomata ii. How do guard cells change shape to
regulate open/closed state? Fig. 32.4 2. Closed stomata -
stimulation to pump out K+ a. Too much water loss during day -
result in decline of CO 2 uptake (sugar production declines), which
is why crop yields decline in droughts 3. Opening and closing
balanced b/w need to save water and need to make sugar Slide 14 V.
Phloem transport (sugar/organic compounds) Chapters 32: Plant
Nutrition and Transport A. Phloem sap i. Sugary solution moving
through seive-tube members ii. Main solute = sucrose iii. Hormones,
inorganic ions, amino acids iv. Moves in ALL directions v. All
phloems have a source and sink - sugar source: where sugar is made
(in leaves by photosynthesis or generated by breaking down from
starch) - sugar sink: where sugar is consumed or stored (growing
roots, shoot tips, fruits, non-photosynthetic stems, etc) -storage
sites can be both sources and sinks depending on environment
(tubers, taproots, bulbs, etc) a. sinks during summer (maximum
photosynthetic activity) b. source during spring (growth) Slide 15
V. Phloem transport (sugar/organic compounds) Chapters 32: Plant
Nutrition and Transport A. Phloem sap vi. How does phloem sap move
from source to sink? - pressure-flow mechanism a. Sugar enters
phloem at source by active transport Fig. 32.5 b. Water follows by
osmosis - makes water pressure high at source c. Sugar actively
transported out of phloem at sink d. Water follows by osmosis -
water pressure low at sink e. Hydrostatic pressure gradient causes
water to flow from source to sink NO MATTER WHERE THEY ARE LOCATED
(sugar goes along for the ride) Slide 16 V. Phloem transport
(sugar/organic compounds) Chapters 32: Plant Nutrition and
Transport A. Phloem sap vii. How can one test the pressure-flow
mechanism? i. Using Aphids Fig. 32.5 a. Aphids feed by inserting
their stylus into phloem of plant b. Releases honeydew (phloem sap
minus nutrients absorbed by aphid) from anus c. Sever aphid from
stylet d. Closer stylet to source, quicker it drips: Slide 17 VI.
The essential nutrient of plants Chapters 32: Plant Nutrition and
Transport A. Hydroponics i. Can be used to determine essential
nutrients ii. Grow plants in a solution (NO soil) of minerals with
known concentration Fig. 32.6 iii. Air bubbled into solution so
roots get enough oxygen for cellular respiration iv. Remove
minerals(s) or change concentration of mineral(s) and compare to
control plant Slide 18 VII. Essential nutrients of plants Chapters
32: Plant Nutrition and Transport A. macronutrients i. 9 out of 17
ii. Need in large (macro) amounts iv. Ca, K, Mg iii. C, N, O, H, S,
P (The big six of course) - Calcium (Ca ++ ) - formation of cell
walls, combines with proteins to form glue of middle lamina,
regulate selective permeability - Potassium (K + ) - cofactor (
non-protein chemical compound bound to an enzyme and required for
catalysis ) of many enzymes, opening and closing stomata (main
solute for osmotic regulation) - Magnesium (Mg ++ ) - component of
chlorophyll, cofactor of many enzymes Slide 19 VII. Essential
nutrients of plants Chapters 32: Plant Nutrition and Transport B.
micronutrients i. The other 8 ii. Need in small (micro) amounts
iii. Fe, Cl, Cu, Mn, Zn, Mo, B, Ni - cofactors of enzymes a. ex. Fe
(iron) is a cofactor of many ETC proteins as it accepts and donates
electrons a. ex. There is one molybdenum (Mo) for every 16,000,000
hydrogens - Recycled over and over again (need very little) Slide
20 VIII. Quality of nutrients in soil determines quality of your
own nutrition Chapters 32: Plant Nutrition and Transport Corn
growth in nitrogen rich (left) vs. nitrogen poor (right) soil Fig.
32.6 Slide 21 IX. Root hairs take up cations using cation exchange
Chapters 32: Plant Nutrition and Transport A. Cation i. Positively
charged ion (K +, Mg ++, Ca ++ ) B. Clay tends to me negatively
charges C. Cations stick to clay - keeps them from draining away D.
Roots secrete H + (acid) in exchange for another cation - this is
why acid rain is not good for soil, it strips away the cation
nutrients E. Anions are easier for roots to absorb (NO 3 -
(nitrate) vs. NH 4 + (ammonium) - anions drain out of soil easily -
unfertile soil, eutrophication Fig. 32.8 Slide 22 X. Parasitic
plants Chapters 32: Plant Nutrition and Transport A. Dodder i.
yellow-orange threads ii. No photosynthesis B. mistletoe i. CAN do
photosynthesis Both dodder and mistletoe may kill host by blocking
too much light or taking too much food iii. Gets organic nutrients
from other plants iv. Uses specialized root to tap into vascular
tissue ii. Supplements diet by siphoning sap from vascular tissue
of host Fig. 32.12 Dodder Mistletoe Slide 23 XI. Carnivorous plants
Chapters 32: Plant Nutrition and Transport A. Sundew and venus
flytrap i. Get nitrogen by digesting flies ii. Sundew uses sticky
sugar substance to attract and trap insects iv. Both secrete
digestive enzymes onto their prey iii. Venus flytrap has touch
sensory hairs that close when touched twice in a row Fig. 32.12
Sundew video Slide 24 XII. Most plants depend on bacteria to supply
nitrogen Chapters 32: Plant Nutrition and Transport A. Recall the
nitrogen cycle i. Plants cant use N 2 (N N) ii. Nitrogen cycle:
Fig. 32.12 Fig. 36.16 iii. Ammonium is a cation (gets stuck to clay
and therefore hard to absorb) iv. Plants prefer Nitrates (anion)
Slide 25 XII. Most plants depend on bacteria to supply nitrogen
Chapters 32: Plant Nutrition and Transport A. Recall the nitrogen
cycle v. Plants will convert nitrates back to ammonium for amino
acid biosynthesis Fig. 32.13 Slide 26 XIII. Legumes house
nitrogen-fixing bacteria Chapters 32: Plant Nutrition and Transport
A. Legumes (plants that produce pods) i. Have nodules on roots
filled with Rhizobium Fig. 32.14 ii. Rhizobium - genus of most
nitrogen-fixing bacteria in roots of legumes - convert N 2 directly
to ammonium, which can be used by plant directly (its already
inside) - excess leaks into soil making it more fertile a. This is
why farmers tend to rotate their crops: one year legume, one year
non-legume iii. Plants give organic molecules to Rhizobium
(mutualistic) Slide 27 XIV. Genetic engineering plants Chapters 32:
Plant Nutrition and Transport A. Gene gun i. Used to shoot foreign
genes into plant cell (or animal cell) ii. DNA integrates into
genome iii. Cells now make new protein Fig. 32.16 Slide 28 XIV.
Genetic engineering plants Chapters 32: Plant Nutrition and
Transport A. Gene gun iv. Many new organisms have been made this
way: - virus resistant cotton plants - potato plants that produce
their own insecticide - slow spoil tomatoes - Can we get plants to
synthesize medicine? Make grain with all eight essential amino
acids? Put genes for nitrogen fixation into non-leguminous plants?
Insect resistant corn Slide 29 I. Experiments on phototropism led
to the discover of plant hormones Chapters 33: Control systems in
plants A. Phototropism i. Growth of a shoot towards light - cell on
dark side elongate faster Fig. 33.1 AIM: How are hormones used by
plants in regulation? ii. mechanism iii. What causes different
growth rate? (video) Slide 30 I. Experiments on phototropism led to
the discover of plant hormones Chapters 33: Control systems in
plants B. Experiment done by Darwin and his son Francis i.
Observation - grass seedlings grow toward light only if shoot tips
were present: Fig. 33.1 AIM: How are hormones used by plants in
regulation? Slide 31 I. Experiments on phototropism led to the
discover of plant hormones Chapters 33: Control systems in plants
B. Experiment done by Darwin and his son Francis i. Observation -
grass seedlings grow toward light only if shoot tips were present:
Fig. 33.1 AIM: How are hormones used by plants in regulation? ii.
Conclusion - tip responsible for sensing light - chemical signal
must be sent from tip Slide 32 I. Experiments on phototropism led
to the discover of plant hormones Chapters 33: Control systems in
plants C. Follow-up experiments done by Peter Boysen-Jensen i.
Experiment: put permeable gelatin block b/w tip and bottom of shoot
or impermeable mica Fig. 33.1 AIM: How are hormones used by plants
in regulation? ii. Result - phototropism occurred with permeable
gelatin iii. Conclusion - chemical signal diffusing through gelatin
from tip Slide 33 I. Experiments on phototropism led to the
discover of plant hormones Chapters 33: Control systems in plants
D. Frits Went extracted the chemical messenger (1926) i.
Experiment: Fig. 33.1 AIM: How are hormones used by plants in
regulation? - put tip on agar (permeable) block to get chemical
signal (hormone) into block - place block on different parts of cut
shoot: Slide 34 I. Experiments on phototropism led to the discover
of plant hormones Chapters 33: Control systems in plants D. Frits
Went extracted the chemical messenger (1926) ii. Conclusion: Fig.
33.1 AIM: How are hormones used by plants in regulation? - blade
bends away from side with chemical - chemical stimulates cell to
elongate - called the chemical auxin (Greek, auxein, to increase)
Aside: Not all plants work this way Slide 35 II. Five major types
of plant hormones regulate growth and development Chapters 33:
Control systems in plants A. Affect growth/development by affecting
division, elongation and differentiation Pg. 662 AIM: How are
hormones used by plants in regulation? B. Trigger signal
transduction pathways (just like in animals) i. Turn genes ON/OFF
ii. Inhibit or activate enzymes iii. Changes in membrane properties
C. Produced in growing parts of plants (apical meristem; young,
growing leaves and developing seeds) Slide 36 II. Five major types
of plant hormones regulate growth and development Chapters 33:
Control systems in plants C. The five major types AIM: How are
hormones used by plants in regulation? i. Auxins - class of
molecules that affects plant growth patterns a. IAA = indolacetic
acid - the major auxin of plants b. Phototropism - Side receiving
sunlight has reduced auxin concentration - auxin causes shaded side
to grow more quickly - IAA is associated with phototropism IAA
Slide 37 II. Five major types of plant hormones regulate growth and
development Chapters 33: Control systems in plants C. The five
major types AIM: How are hormones used by plants in regulation? i.
Auxin - class of molecules that affects plant growth patterns c.
Geotropism (gravitropism) - growth of plant towards or away from
gravity - negative geotropism: shoots grow upward, away from
gravity - gravity causes auxins to be more concentrated on lower
side of horizontal plant and less concentrated on upper side. -
cells on lower side elongate (grow) quicker than on upper sideplant
bends upward (video) Slide 38 II. Five major types of plant
hormones regulate growth and development Chapters 33: Control
systems in plants C. The five major types AIM: How are hormones
used by plants in regulation? i. Auxin - class of molecules that
affects plant growth patterns c. Geotropism (gravitropism) -
positive geotropism: roots grow toward pull of gravity - auxins
have opposite effect in roots - Result: root bends downward - they
still concentrate on lower side of a sideways root, but this
INHIBITS elongation. Fig. 33.3 Slide 39 II. Five major types of
plant hormones regulate growth and development Chapters 33: Control
systems in plants C. The five major types AIM: How are hormones
used by plants in regulation? i. Auxin - class of molecules that
affects plant growth patterns c. Auxin made in apical meristem of
terminal bud - inhibits development of lateral (axillary) buds -
mechanism of apical dominance - also made in root apical meristem
inhibit formation of lateral roots Taller seedlings received auxin
(Fig. 33.3A) Slide 40 II. Five major types of plant hormones
regulate growth and development Chapters 33: Control systems in
plants C. The five major types AIM: How are hormones used by plants
in regulation? i. Auxin - class of molecules that affects plant
growth patterns d. How do auxins cause elongation? - hypothesis:
they weaken cell walls - stimulate proteins to pump protons (H+)
into cell wall - activate enzymes to break H-bonds b/w cellulose
fibers - cells swell as more water can now fit within due to cell
wall stretching Fig. 33.3 Slide 41 II. Five major types of plant
hormones regulate growth and development Chapters 33: Control
systems in plants C. The five major types AIM: How are hormones
used by plants in regulation? i. Auxin - class of molecules that
affects plant growth patterns e. Other effects of auxins - induces
division in vascular cambium (promotes growth in diameter) -
produced by developing embryo - promotes fruit growth - some plants
develop fruit w/o fertilization if you spray them with auxin Slide
42 II. Five major types of plant hormones regulate growth and
development Chapters 33: Control systems in plants C. The five
major types AIM: How are hormones used by plants in regulation? ii.
Cytokinins (kinins) a. Class of growth regulators that promote cell
division (cytokinesis) b. Produced mainly in roots c. Effects of
kinins are influenced by concentrations of auxins - auxins from
terminal bud inhibit axillary bud growth - cut off terminal bud -
cytokinins from roots can now activate axillary buds (auxins
overpower cytokinins) Fig. 33.4 d. Auxins and cytokinins are
antagonistic hormones Slide 43 II. Five major types of plant
hormones regulate growth and development Chapters 33: Control
systems in plants C. The five major types AIM: How are hormones
used by plants in regulation? ii. Cytokinins (kinins) e. Other
effects of cytokinins - affect root growth and differentiation -
delay aging (florists sometimes spray cytokinins onto flowers) -
breaking seed dormancy (germination) Slide 44 II. Five major types
of plant hormones regulate growth and development Chapters 33:
Control systems in plants C. The five major types AIM: How are
hormones used by plants in regulation? iii. Gibberellins Fig. 33.5
a. History of discovery - Fungus of genus Gibberella - infects rice
seedlings, causes them to grow very tall - rice topples over and
dies before flowering - Japanese called it foolish seedling disease
- Japanese scientist discovered chemical released by the fungus
that caused disease - named it Gibberellin - it was later
discovered to exist naturally in plants Foolish seedling diseased
plants Control plants Slide 45 II. Five major types of plant
hormones regulate growth and development Chapters 33: Control
systems in plants C. The five major types AIM: How are hormones
used by plants in regulation? iii. Gibberellins b. More than 100
known c. Produced in roots and young leaves d. Stimulates stem
elongation and cell division in stems - enhances auxins e. Enhance
fruit development sprayed with gibberellins control Slide 46 II.
Five major types of plant hormones regulate growth and development
Chapters 33: Control systems in plants C. The five major types AIM:
How are hormones used by plants in regulation? iii. Gibberellins f.
Terminate seed and bud dormancy (activate them) g. Induce some
biennial plants to flower during 1st year of growth - spray seeds
with gibberellins and they germinate regardless of environmental
requirements - naturally: when seed absorbs water, embryo triggered
to release gibberellins Slide 47 II. Five major types of plant
hormones regulate growth and development Chapters 33: Control
systems in plants C. The five major types AIM: How are hormones
used by plants in regulation? iv. Abscisic acid (ABA) a. Inhibits
many plant processes - Ex. inhibits germination - must inactivate
ABA for germination to occur - inactivation triggered by cold
temperature in some seed (winter inactivates for spring
germination) - seeds activated by water: water flushes ABA out of
seed - prominent in desert seeds after a hard rain: Fig. 33.6 b.
Ratio of gibberellins to ABA determines germination in many seeds
(antagonistic hormones) c. ABA signals stomata to pump out K + when
plant wilts Slide 48 II. Five major types of plant hormones
regulate growth and development Chapters 33: Control systems in
plants C. The five major types AIM: How are hormones used by plants
in regulation? v. Ethylene a. History - observed that fruit ripened
in sheds with kerosene stoves - hypothesized that heat caused
ripening - kerosene stoves were replaced with cleaner-burning
stoves - fruit did not ripen as quickly - need to modify hypothesis
- ethylene is a gaseous byproduct of burning kerosene Slide 49 II.
Five major types of plant hormones regulate growth and development
Chapters 33: Control systems in plants C. The five major types AIM:
How are hormones used by plants in regulation? v. Ethylene c.
Ethylene triggers fruit ripening and other aging processes (e.g.
apoptosis) b. Plants produce ethylene Slide 50 II. Five major types
of plant hormones regulate growth and development Chapters 33:
Control systems in plants C. The five major types AIM: How are
hormones used by plants in regulation? v. Ethylene - ethylene
diffuses from fruit to fruit through air (its a gas!) d. Fruit
ripening (one bad apple does spoil the lot) - triggers enzymatic
breakdown of cell walls (softens fruit) - triggers conversion of
starch to sugar (sweetens fruit) - new scent and color attracts
animals (operant conditioning) to eat and disperse seeds - what
would happen if you put fruit in a plastic bag and sealed it? -
many fruits are picked green, placed in large tanks, and ethylene
is pumped over them for ripening Fig. 33.7 - CO 2 inhibits action
of ethylene (slows ripening): pick apples in AUTUMN, pump CO 2 over
them to inhibit ripening, and sell the following summer Slide 51
II. Five major types of plant hormones regulate growth and
development Chapters 33: Control systems in plants C. The five
major types AIM: How are hormones used by plants in regulation? v.
Ethylene - color change e. Falling leaves - leaves lose chlorophyll
unmasking other pigments - new pigments made as well - leaves
stripped of essential elements before falling off - petiole
separates from stem 1. Abscission layer Fig. 33.7 - region of
separation (parenchyma cells with thin walls, weakened by enzymes)
- triggered by increasing levels of ethylene and decreasing level
of auxin (antagonistic hormones) 2. Triggered by shortening days
Slide 52 II. Five major types of plant hormones regulate growth and
development Chapters 33: Control systems in plants D. Hormones used
extensively in agriculture AIM: How are hormones used by plants in
regulation? i. Ex. Low dose of auxins to prevent fruit from falling
off before being picked Fig. 33.8 Slide 53 II. Five major types of
plant hormones regulate growth and development Chapters 33: Control
systems in plants E. Growth responses and biological rhythms in
plants AIM: How are hormones used by plants in regulation? i.
Tropisms Fig. 33.9 b. Types a. Orient plant growth toward or away
from environmental stimuli 1. Phototropism 2. Gravitropism
(geotropism) Slide 54 II. Five major types of plant hormones
regulate growth and development Chapters 33: Control systems in
plants E. Growth responses and biological rhythms in plants AIM:
How are hormones used by plants in regulation? i. Tropisms Fig.
33.9 b. Types a. Orient plant growth toward or away from
environmental stimuli 1. Thigmotropism - growth or movement in
response to touch (Greek, Thigma, touch) - Ex. Tendril of pea plant
i. Grows straight until it touches something ii. Contact causes
cell to grow at different rates on opposite sides of tendril (just
like phototropism and gravitropism) - slower growth in area of
contact - result: plant coils around branch - great for support
while heading for sun (phototropism) Slide 55 III. Lichen is not to
be confused with plants Chapters 33: Control systems in plants A.
Lichens AIM: How are hormones used by plants in regulation? i.
Associations of millions of algae or cyanobacteria held in a
network of fungal hyphae a. Mutualism is so tight that lichens are
named as a single species b. Photoautotrophs supply fungus with
food, and fungus gives photoautotrophs a suitable environment to
live Fig. 17.8 c. Can live where little or no soil (recall primary
succession) Slide 56 IV. Kingdom Fungus Chapters 33: Control
systems in plants A. Fungus AIM: How are hormones used by plants in
regulation? Fig. 17.16 b. Fungi are heterotrophs that absorb food
after digesting with enzymes outside their body a. Greek, mycos,
fungi (mycelium, mycorrhizae, etc) c. Often saprophytes d. Cells
have cell wall made of chitin e. Mushroom, mold and yeast f. Most
reproduce sexually (fertilization) and asexually (spores or
fragmentation) - spend most of life in haploid form g. Mushroom is
spore-bearing fruiting body of a fungus hyphae
