Highlights
of Plant
Evolution
Chart:
I. Bryophytes - mosses = many plants growing in a tight pack.
• No waxy cuticle and do not retain developing embryos w/i mother plant’s
gametangium.
• Need water to reproduce; sperm are flagellated, must swim through water
to reach eggs
• No vascular tissue to carry water(grow low to ground) and lack lignin
• Like damp, shady places
• Green spongy plant = gametophyte (male & female are separate plant
shoots)(n)
• Taller brown shoot with a capsule, grows out of gametohyte = sporophyte
(2n)
Alternation of Generations 2 generations that take
turns producing each other
• Gametophytes produce
eggs and sperm; must
unite to form a zygote,
which forms new
sporophytes.
• Sporophytes produce
spores
• Spores can develop into a
new organism without
uniting, & have a tough
coat to resist harsh
environments.
• The new organism then
produces gametophytes
again.
• Gametophyte = larger
more obvious plant in
• Moss- Gametophyte (left) and Archegonium
(female gametophyte) (right)
(Antheridium = male gametopyte.)
• Sporophyte generation (left) and Sporangia
(right)
• Moss is cool! E.C. for bringing in moss with both
generations. (In late spring.)
• II. Ferns - diverse with 12,000 species, most in tropics, many in
temperate woodlands of U.S.
• Evolution of vascular tissue (xylem and phloem)
• Sperm are still flagellated-must swim through a film of water to fertilize
eggs
• Are still seedless - have spores
• During Carboniferous Period, ferns in swamp forests converted to coal (black sedimentary rock made up of fossilized plant material)
• Alternation of
Generations in
ferns.
• Sporophytes
are diploid and
gametophytes
are haploid
• Sporophyte is
the dominant
stage in ferns.
(Gametophyte
was dominant
in mosses)
• Heart shaped
gametophyte =
prothallus
• III. Angiosperms - flowering
plants, dominate most regions
• 250,000 species vs. 700 conifer
species
• Supply nearly all our food and
fiber for textiles, some lumber
• Refined vascular tissue - water
transport more efficient
• Evolution of flower = responsible
for unparalleled success
• Flowers - display male and female
parts
• Insects and animals transfer pollen
from male part of one flower, to
female part of another flower.
Advantage? (vs. wind)________
• Flower = short stem w. modified
leaves: sepals, petals, stamens,
carpels.
Label flower to left w. all
flower terms below:
Sepals - green, enclose flower
before it opens
Petals - attract insects & other
pollinators
Stamen - filament (stalk)
bearing a sac called anther.
Anther is male organ in
which pollen grains
develop.
Carpel = sticky tip called
stigma, which traps pollen,
the style (stalk) and the
ovary, a chamber
containing one or more
ovules. Egg develops
here.
Angiosperm life cycle is above:
• Sporophyte is the familiar plant; female gametophyte is w/I the ovule, & male
gametophyte is the pollen.
• Pollen lands on stigma, tube goes down to ovule, deposits 2 sperm nuclei w/I
female gametophyte = Double fertilization.
• One sperm cell fertilizes egg making zygote, developing into embryo.
• Second sperm cell fertilizes another female gametophyte cell which develops
into a nutrient-storing tissue called endosperm.
End of Ch. 16
Angiosperms cont:
• Embryo then has food w/I ovule
• Ovule develops into a seed
• Seed is enclosed W/I ovary = not
naked.
• Fruit = ripened ovary of flower
• Fruit protects and helps disperse
seeds
• Animals help disperse seeds too!
• All fruit and vegetable crops are
angiosperms
• We will re-visit flowers and fruits
in Ch.28 & in labs.
• Issues:Tropical rain forests are
being destroyed for agricultural
Coniferous forests are being
destroyed for lumber and paper.
Can you help???
Chapter 28: Flowering
Plants
Most of your notes for this Chapter will be found in your
Flowering Plant Lab. However, here are some notes in addition
to your lab.
•
•
•
•
•
Angiosperms have dominated
earth for 60 million years;
250,000 million species are
known today.
Monocots include orchids,
palms, lilies, grains, grasses.
Dicots include shrubs, trees
(except for conifers),
ornamental plants, many food
crops.
Know traits of each! (Lab) &
See left.
3 Plant organs: roots, stems,
leaves (Lee also lab)
1. Roots: Root hairs-increase
surface area of root for
absorption
Large taproots - store food
such as starch for plant (Ex:
carrots, turnips, sugar beets,
sweet potatoes.)
2. Stems - Terminal bud is at apex of stem
when plant stem is growing in length.
Axillary buds, in angle formed by a leaf
and stem) are dormant.
Terminal bud produces hormones
inhibiting growth of axillary buds = apical
dominance, so plant can grow up to sun.
Axillary buds begin growing and develop
into branches under certain conditions.
What is “pinching back?”
3 kinds of Modified stems:
Runner in a strawberry plant = horizontal
stem - new plants emerge from tip of
runner = asexual reproduction
Rhizome of an iris plant =horizontal
underground stems = store food, & can
bud new plants
Tubers are rhizomes ending in enlarged
structures (potatoes). Eyes of potato are
axillary buds, can grow when planted.
3. Leaves - flat blades (for light collection) and
petioles (joins leaf to stem.) Celery is a big
petiole.
Tendrils = modified leaves for climbing
and support .
Spines of a cactus = modified leaf parts
protecting plant. Cactus stem is
photosynthetic.
• Plant Cells - have chlorophyll, large
central vacuole, some have a multipart cell
wall:
• Primary cell wall - laid down first
• Secondary cell wall - deposited between
plasma membrane and primary wall, more
rigid for support
• Parenchyma cells - most abundant cell, for
food storage, photosynthesis. Only primary
cell walls.
• Collenchyma cells - provide support in
growing parts of plant. Only primary cell
walls.
• Sclerenchyma cells - have thick secondary
walls with lignin (wood). When mature,
most are dead - rigid cells support plants.
Make rope and clothing.
• 2 Plant Vascular Tissues:
1. Xylem - contains water conducting cells move water & minerals up stem
2. Phloem -contains food conducting cells transport sugars from leaves or storage tissue
to other parts of plant
• 3 Tissue Systems continuous throughout
plant:
1. Dermal-covers, protects, waxy coating
(epidermis)
2. Vascular- xylem and phloem; support,
transport
3. Ground - bulk of young plant, fills spaces
between epidermis and vascular.
Photosynthesis, storage, support.
Types of ground tissue:
Cortex - in root,cells store food, take up
water & minerals.
Endodermis - selective barrier in cortexdetermines which substances pass between
cortex and vascular tissue.
Pith - fills center of stem in dicots, food
storage.
(Con’t.)
Ground Tissue continued:
Stomata - in epidermis of leaf and some stems, are tiny pores between
guard cells - minimizes water loss, allow gas exchange.
Mesophyll - ground tissue of a leaf, for gas exchange and photoshythesis
???Can you name all parts of this leaf below ??? Label them!
Upper epidermis, Lower epidermis, Mesophyll, Cuticle, Vein, Xylem,
Phloem, Guard cells, Stomata, Palisade Layer, Spongy layer
• What kind of plant organ is this, monocot or
dicot, and why?
______________________________________
______________________________________
__________
•
•
Review the structure of a flower, left.
Go over life cycle of an angiosperm,
below.
•
•
•
This diagram shows how the male gametophyte (pollen) and
female gametophyte (embryo within ovule) develop.
The ovary may contain several ovules; only 1 is shown here.
Please go over Steps 1-3 for the male and for the female on the
diagram above. Males have ____surviving cells; females have ___.
•
Above diagram shows pollination and double fertilization steps:
1. Pollination
2. Pollen form 2 sperm
3. Sperm travel through a pollen tube to ovule
4. Double fertilization occurs:
–
–
one sperm fertilizes egg forming diploid zygote which becomes the embryo;
other sperm joins to form the triploid central cell, which develops into endosperm, nourishing the
embryo
• Seed Formation:
Embryo develops cotyledons.
These organs absorb nutrients
from endosperm.
Embryo develops into mature
seed with tough protective seed
coat enclosing endosperm.
Seed becomes dormant until seed
germinates.
Dormancy allows time for seed
dispersal, favors survival for
good environmental contitions
• Fruit formation:
Fruit = mature ovary
Houses and protects seeds,
disperses them from parent
Seed Germination:
• Seed takes up water and expands, ruptures its seed coat
• Embryo resumes growth (from dormancy)
• Embryotic root emerges, then shoot; a hook forms near its tip (protection)
• True leaves expand from shoot tip, and photosynthesize
•
In pea, cotyledons remain behind in soil and decompose (see above)
• In beans, cotyledons emerge from soil and become seed leaves, which photosynthesize
• Only small fraction of seedlings live to reproduce
Plant Growth:
• Plants have indeterminate growth continue to grow as long as they live increases exposure to sunlight
• Have a finite life span: 3 examples:
∆ Annuals - mature, reproduce and die
in 1 year or growing season. Ex:
wheat, corn, rice, impatients
∆ Biennials - live for 2 years; flower
and seed occur during second year.
Ex: carrots
∆ Perennials - live and reproduce for
many years. Ex: trees, shrubs, some
grasses.
• Primary Growth = lengthening
Meristem - cells that divide and
generate new cells and tissues (See
lab and left diagram)
Secondary Growth = thickening
• Wood - dead xylem tissue
• Vascular cambium - gives rise to
secondary phloem and secondary
xylem. Secondary xylem is produced
each year = thickness of perennial
and/or wood. This results in annual
growth of rings. Each tree ring has
cylinder of spring wood (larger cells)
and of summer wood.
• Cork cambium - produces cork (dead
when mature, protects stem)
• Everything external to the vascular
cambium ( secondary phloem, cork
cambium, cork) = bark
• What happens if you remove the bark
from a tree? __________________
• Extra credit lab/ worksheet is available
about counting tree rings.
• Pollinators (Vectors) and
flowers = mutually beneficial
relationship
• How do flowers benefit?
(Pollination and seed dispersal)
• How do pollinators benefit?
(Nectar and pollen for food.)
• Color and fragrance advertise
for pollinators
• Birds see red/pink
• Bees - smell
• See next Set # 4 For Video
Clips of these concepts!
Chapter 29 The Working Plant
•
•
•
•
•
Sap -watery solutions moving through
vascular system.
In xylem it carries water and nutrients
from roots to leaves and stems.
In phloem it transports sugar already
made, from leaves to other parts of
plants.
Sap is made in Spring by converting
starch that was made the previous
summer into sugars.
It takes 40 liters of maple tree sap to
produce 1 liter of maple syrup.
•
•
•
•
•
•
•
•
•
Plants get CO2 from air (through stomata),
minerals and H2O from soil,(through root
hairs) and O2 from soil.(through stomata).
A plant releases more O2 from photosynthesis
than it consumes by respiration
Plant nutrition: all minerals that enter a plant
root are dissolved in water
Go through epidermis & cortex of root;
plasma membrane of root cells
(selectively permeable); to xylem.
Mycorrhiza (fungi) help in absorption
Macronutrients-need in large amounts:
carbon, oxygen, hydrogen, nitrogen, sulfur,
phosphorus, calcium, potassium, and
magnesium
Micronutrients - need in extremely small
amounts: iron, chlorine, copper, manganese,
zinc, molybdenum, boron, nickel. Mainly
components of enzymes.
See p. 641-642 for uses of all nutrients
Deficiencies - quality of soil affects our own
nutrition - Corn on left grown in nitrogen rich
soil; on right in nitrogen poor soil
•
Bacteria help with nitrogen nutrition: 3 types of soil bacteria:
1. Nitrogen-fixing bacteria - converts N2 in air to ammonium
2. Ammonifying bacteria - adds ammonium by decomposing organic matter
3. Nitrifying bacteria - converts soil ammonium to nitrate - plants take this up
•
Plants then convert nitrate back to ammonium to make proteins/organics.
•
•
•
Legumes (soybean, clover, peas, alfalfa) have root nodules that
contain nitrogen-fixing bacteria called Rhizobium.
Symbiotic relationship - bacteria have a place to live and receive
carbohydrates/organics from plant. Plants get ammonium ions
released into soil.
Why do some farmers rotate their crops? Ex: One year corn, the
next year soybeans? ___________________________________
The Transport of Water:
• Pulled up plant through
transpiration (loss of water
vapor from plant,) through the
stomata
• Cohesion = water molecules
stick together, are pulled up
together
• Adhesion = water molecules
adhere to cellulose molecules in
walls of xylem cells
• A continuous string of water
molecules move up tube
• Molecules of water break off
from the top of the string as they
leave the leaf. String is kept
tense and pulled upward as long
as transpiration continues.
• No energy expenditure by plant
• Called: Transpiration-cohesiontension mechanism
Chapter 29 continued...
•
•
•
•
•
Transpiration - greatest on sunny, warm, dry and windy days
Maple tree can lose more than 200 L of water per hour
Unless rehydrated, plant could eventually die
Leaf stomata can help plants adjust transpiration rates-controls opening by
changing shape
Open during day and close at night, saving water. May close during day if
plant is losing water too fast.
The Transport of Sugars:
• Phloem sap moves in various
directions in plant
• Phloem moves sugar from a
source (leaf) to a sink (root or
fruit)
• Pressure-flow mechanism - the
building of water pressure at
source end of phloem tube, and
the reduction of water pressure at
the sink end causes water to flow
from source to sink, carrying
sugar with it.
Plant Hormones -control plant growth
and development - affect division,
elongation, differentiation of cells
• 5Major types:
• 1. Auxin-produced by apical
meristem, stimulates growth of
shoot-causes cells to elongate.
• Ex: Cells elongate (more auxin) on
dark side of stem, causes stem to
bend on opposite side (toward
light)
• Requires certain concentrations:
too much = inhibits stem
elongation.
• Usually, it inhibits roots (except in
high concentrations it can elongate
roots.)
•
•
•
•
•
2. Ethylene - a gas which triggers
aging responses - fruit ripening,
dropping of leaves. (See left top
photo)
Why does “one bad apple spoil the
whole bunch?’________________
3. Cytokinins - growth regulators,
promote cell division. In roots,
embryos, fruits. Stimulate growth
of axillary buds (branches and
bushy.)
Why are cytokinins used by
growers of Christmas trees?
4. Gibberellins - stimulates cell
elongation and cell division in
stems. Can influence fruit
development. Used in grapes-larger
and more farther apart in the
cluster. (See left bottom photo)
•
•
•
5. Abscisic Acid - slows growth. Ex:
seed dormancy, esp. during adverse
conditions
During drought, causes stomata to
close during wilting, preventing
further water loss
Photo: desert plants grew from seeds
that germinated just after a hard rain were dormant in parched soil
beforehand.
Summary of plant hormones:
The End
Photosythesis
What is
matter?
• Matter – anything that
occupies space and has
mass
– Composed of chemical
elements
• Element – cannot be
broken down into other
substances
– 92 natural elements
• EX – oxygen, carbon,
copper
– Each element has a
symbol from its name
• EX - O, C, Cu
– Essential to life…(96%)
• O, C, H, N
– Trace elements…(4%)
• Ca, P, K, S
Compounds
• Compound – a
substance containing 2
or more elements in a
fixed ratio
H2O = water
– More common than
elements
Glucose
Sucrose
NaCl = table salt
• Atom –
– Indivisible – Greek
– Smallest unit of matter
that retains the properties
of an element
ATOMS
Atomic Structure –
*Nucleus – central core of the atom,
contains protons and neutrons
*Proton – positively charged
*Neutron – no charge
*Orbitals - outside the nucleus
*Electron – negatively charged
Attraction between protons and
electrons keep the electrons nearby
the nucleus.
How is one element
different from another
element?
• Atomic number – same
as the number of
protons
– Oxygen has 8 protons
• If the atom is electrically
neutral (number of protons =
number of electrons) then
the atomic number also is
the same as the number of
electrons.
• Mass number – sum of
the numbers of protons
and neutrons in a
nucleus
Periodic Table of Elements
Isotopes
• Isotopes – elements with the same number of
protons and electrons, but a different number
of neutrons
Radioactive Isotopes – the nucleus will decay, giving off
particles and energy
Chemical Properties of Atoms
•
•
•
•
Electrons determine how an atom will behave.
Electrons that are farther from the nucleus have greater energy.
Electron shells – 1st = 2 electrons, 2nd = 8 electrons, 3rd = 8 electrons
If an electron shell is not full the atom is likely to react with other
atoms in a chemical reaction.
• If the electron shell is full it is unreactive (chemically inert).
Chemical Bonding
Chemical bonds – formed by atoms trying to fill the outer most
electron shell
• Ionic bonds – attraction
between oppositely charged
ions (electron is
transferred)
– Ions are formed by either
gaining or losing an electron.
• Atoms like to have full energy
shells and will easily gain or
lose 1-3 electrons to do it.
• Example – Na has 1é in its outer
shell and Cl has 7é in its outer
shell. Na can lose 1é to become
Na+1 and and Cl can gain 1é to
become Cl-1 and both will have a
full outer shell.
• Covalent bonds –
occur when two atoms
share one or more
pairs of outer shell
electrons.
– Molecule – formed by
atoms held together by
covalent bonds.
• Chemical Reaction –
changes in the chemical composition of
matter
•For a balanced chemical reaction the number of each element
must be equal on both sides of the reaction. Reactions cannot
create or destroy matter, it can just rearrange it.
Photosynthesis
Photosynthesis is all about
feeding the biosphere
• Photosynthesis converts energy of sunlight into the chemical
energy of sugar and organic compounds.
– Almost all plants, some protists and some bacteria
• Autotrophs…
–
–
–
–
–
An organism that makes all its own organic matter from inorganic nutrients
Self feeders
Require inorganic compounds - CO2, H2O and minerals
Make organic compounds – carbohydrates, lipids, proteins, nucleic acids
producers
• Heterotrophs…
–
–
–
–
Cannot make organic molecules from inorganic ones
Other feeders
We must eat!
Depend on autotrophs for their organic fuel and material for growth and
repair
– consumers
Sites of Photosynthesis
• Chloroplasts – organelle responsible for photosynthesis
– Leaves are the major site of photosynthesis (all green parts of a plant
have chlorophyll and chloroplasts and can undergo photosynthesis)
•Double membrane envelope
•Inner membrane encloses the stroma – thick
fluid, where sugars are made from CO2
•Thylakoids – sacs suspended in the stroma,
stacked in grana, where the chlorophyll
molecules that capture the light energy are
stored
Parts of the leaf…
• Mesophyll – cells
making up the green
tissue on the interior of
the leaf
– Palisade mesophyll –
upper portion, densely
packed
– Spongy mesophyll –
lower portion, air spaces
• Stomata – openings
through which CO2,
H2O and O2 gases are
exchanged (most H2O
comes up from the
roots)
Photosynthesis Chemical Reaction
•
•
•
•
Reactants = 6 CO2 and 6 H2O
Products = C6H12O6 and 6 O2
Electrons are added to CO2 to produce sugar
Sunlight provides the energy to split the H2O molecules
and release O2 into the atmosphere
Photosynthesis:
A Simple Summary
1. Light Reactions
•
•
Convert solar to
chemical energy
Synthesize ATP (energy
storage) and NADPH
(electron carrier)
2. Calvin Cycle (Dark
Reactions)
•
•
Makes sugar from CO2
Uses ATP and NADPH
from light reactions
Light Reactions
• Sunlight is radiation or electromagnetic energy.
• We are able to see only light that is reflected from an
object.
• EX – green leaves absorb red-orange and blue-violet light;
therefore, reflecting green light. Chloroplasts convert the
absorbed energy.
Chloroplast
Pigments
Found in photosystems…
1. Chlorophyll a –
absorbs blue-violet
and red light
–
Participates directly in
the light reactions
2. Chlorophyll b –
absorbs blue and
orange light
–
Helps light reactions by
increasing the range of
light that can be
absorbed
3. Carotenoids – absorb
blue-green light
–
Absorb and dissipate
excessive light that may
• Photon – fixed
quantity of light
energy
• Pigment
molecules absorb
photons of light
that “excite” the
electrons to a
higher energy
state
• As the electron
“falls” back to the
normal state is
releases energy
as heat or light
energy
Photosystems
and Light
• Photosystems – have clusters of pigment molecules that act as
antennae for photons of light.
• Photons of light “jump” from pigment to pigment until it reaches the
Reaction Center containing chlorophyll a.
• Next to the reaction center is the primary electron acceptor
which traps the light excited electron energy into ATP or NADPH.
Two Types of Photosystems
1. Water splitting
photosystem –


Light energy to extract
electrons from water
Releases O2 as a waste
product
2. NADPH producing
photosystem

Produces NADPH by
transferring light excited
electrons from
chlorophyll to NADP+
•An electron transport chain
connecting the two photosystems
releases energy used to make ATP
• Light reactions as seen in the thylakoid membrane.
• Electron transport chain pumps H+ ions across a
membrane.
• ATP synthases use the energy stored by the H+
gradient to make ATP.
Calvin Cycle
(Dark Reactions)
Calvin Cycle
• It is a cycle because the
starting material is
regenerated with each
turn of the cycle.
• Inputs…
– CO2, ATP and NADPH
• Outputs…
– Glyceraldehyde 3phosphate
• Raw material to make
glucose and other organic
molecules
C3 vs. C4 vs. CAM
• C3 Plants – use CO2 directly from the air
– EX – soybean, wheat, oats, rice…
– Dry weather can decrease the rate of photosynthesis and crop
productivity because stomata are closed to prevent water loss and
no CO2 gas exchange occurs.
• C4 Plants – use an enzyme to incorporate CO2
–
–
–
–
EX – corn, sorghum, sugarcane
Save water without slowing photosynthesis
When hot the stomata are closed to prevent water loss
Continues sugar production by using an enzyme to incorporate CO2
into a 4 C compound instead of the normal 3 C compound.
•CAM Plants – opens stomata at night to let in CO2 and to prevent water
loss
–Ex – pineapple, cacti, succulents
–Once the CO2 is inside the leaf it forms a 4 C compound
–Bank CO2 at night and release it to the Calvin Cycle during the day
Photosynthesis Review
Greenhouse Effect – warming
induced by CO2
Cellular
Respiration
Energy Cycle
CO2 + H2O
C6H12O6 + O2
• Photosynthesis – uses
light energy to make
organic molecules
– Chloroplasts
– Chlorophyll
– Producers
• Respiration – harvests
energy stored in sugars
and organic molecules
– Mitochondria
– Consumers
Types of Energy
• ENERGY – capacity to do work
– Kinetic Energy – energy of motion
– Potential Energy – energy because of its location or
arrangement
– Conservation of Energy – energy can neither be created
nor destroyed
• ENTROPY – measure of disorder or randomness
• Chemical Energy – energy stored in the chemical
bonds of molecules; a form of potential energy