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Hypotheses for Origin of Life on
Earth
• Divine origin
• Extraterrestrial Origin
• Abiotic Origin
.475
.7
1.7
2
3.5
3.8
4
Oldest fossil is
of bacteria 3.5
Billion years old
What are
stramatolites?
Mitochondria and Chloroplasts are thought to have been engulfed by
Archaea Bacteria and formed the first eukaryotic cells - 3 bya
P 494
Ancient Reducing Atmosphere
• Oparin and Haldane proposed that Earth’s
ancient atmosphere was reducing rather
than oxidizing.
• Why was there no free oxygen in Earth’s
early atmosphere?
• Why would the first life not evolve in an
oxidizing atmosphere?
Miller and Urey simulated
Earth’s early atmosphere
electricity simulated lightning
Why did they use uV light?
An alternate atmosphere
contained carbon monoxide,
carbon dioxide, nitrogen gas
and water vapor
Experiments have
produce all 20 amino
acids, sugars, lipids,
purines, pyrimidines
What is the importance of
amino acids?
What is the importance of
nucleic acids?
Lightning and uV light
provided energy for
the formation of larger
molecules and
polymerization
Protobionts
• Aggregates of molecules that:
• can start maintain a different internal
environment (homeostasis)
• can show rudimentary metabolism (catalytic
reactions and modifications)
• can show excitability (membrane potential)
• can reproduce themselves
• maintain genetic material
Protobiont Examples
• Coacervate (Oparin)
made of
polypeptides nucleic
acids and
polysaccharides
• Proteinoid
Micorspheres (Fox)
• Liposomes
RNA not only could
replicate itself, but it could
also act as a catalyst
eg. Making proteins
RNA with the
best autocatlytic
activity would to
predominate
Formerly
eubacteria
Archaea live in
extreme
environments
and have cell
walls with no
peptidoglycan
Most bacteria
range from 15 um while
eukaryotes
range from 10100 um
Coccus shape
Bacillus shape
Hilical or spiral
shape
eg. Spirochetes
Simple cell wall with
relatively large amounts
of peptidoglycan
Penicillin prevents
crosslinking in the
peptidoglycan and
prevents the formation
of a functional cell wall
More complex cell
wall with less
peptidoglycan but
with an outer
membrane with
lipopolysaccharides
-carbohydrates
bonded to lipids
Nucleoid region containing
genophore
-prokaryotic DNA
Prokaryotes have
smaller ribosomes that
respond to different
antibiotics that prevent
them from doing
protein synthesis
Trypanosoma is a
kinetoplastid from the
Kingdom Euglenozoa
it is the cause of African
sleeping sickness which
is spread by the bite of
the Tsetse fly
Kinetoplast- an organelle
Ceratium is a dinoflagellate from
the Kingdom Aveolota
Pfiesteria piscicida is
another dinoflagellate that
can produce toxins that can
result in red tides
Their characteristic shape is reinforced by internal plates
of cellulose
they have two flagella set in perpendicular grooves which
result in its characteristic spinning motion
The apical
complex is its
characteristic
structure
Just the micronucleus undergo meiosis and
syngamy which increases genetic diversity
Rhizopods, Actinopods & Foraminiferans move by
pseudopodia or false foot
the microtubules and microfilaments of the cytoskeleton help
in amoeboid movement
Foraminiferans - pore bearing shells
many have symbiotic algae in which they derive benefit from photosymthesis
Foram fossil are excellent markers for dating marine sediment and sedimentary rock
Plasmodial Slime
Mold
is composed of ONE
multinucleated cell
or amoeboid mass
called a plasmodium
most species are
diploid
Stramenopila
• Diatoms
• Golden Algae
– have yellow and brown caroten and
xanthphyll acessory pigments
• Water Molds and their relatives
(Oomycota)
– lack chloroplasts
– unicellular or have coenocytic hyphae
– cause of the Irish potato famine
• Brown Algae
Isomorphic
alternation of
generations in
Ulva
CHAPTER 29
PLANT DIVERSITY I: HOW PLANTS
COLONIZED LAND
Section A: An Overview of Land Plant Evolution
1. Evolutionary adaptations to terrestrial living characterize the four main
groups of land plants
2. Charophyceans are the green algae most closely related to land plants
3. Several terrestrial adaptations distinguish land plants from charophycean
algae
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Introduction
• More than 280,000 species of plants
inhabit Earth today.
• Most plants live in terrestrial environments,
including deserts, grasslands, and forests.
– Some species, such as sea grasses, have
returned to aquatic habitats.
• Land plants (including the sea grasses)
evolved from a certain green algae, called
charophyceans.
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Problems Aquatic Plants Face
in a Terrestrial Environment
• Obtaining enough
water
• transporting water
and dissolved
substances from
restricted areas of
intake to other areas
• Preventing
dessication
• Maintaining enough
moist surface area for
gas exchange
• Supporting a large
plant body against
gravity
• carry out reproduction
in an environment
where sperm, zygote
and embryo will dry
out
• withstanding extreme
fluctuations in
environment
1. Evolutionary adaptations to
terrestrial living characterize
the four main groups of land
plants
• There are four main groups of land plants:
•
•
•
•
bryophytes, pteridophytes, gymnosperms,
and angiosperms.
The most common bryophytes are
mosses.
The pteridophytes include ferns.
The gymnosperms include pines and
other conifers.
The angiosperms are the flowering plants.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Bryophytes
• Mosses
• Liverworts
• Hornworts
• The great majority of modern-day plant
species are flowering plants, or
angiosperms.
– Flowers evolved in the early Cretaceous
period, about 130 million years ago.
– A flower is a complex reproductive structure
that bears seeds within protective chambers
called ovaries.
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• Bryophytes, pteridiophytes, gymnosperms,
ands angiosperms demonstrate four great
episodes in the evolution of land plants:
– the origin of bryophytes from algal ancestors
– the origin and diversification of vascular plants
– the origin of seeds
– the evolution of flowers
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Fig. 29.1
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Homologies between
Charophytes and Plants
• Homologous
chloroplasts
– chlorophyll b, betacarotene
– thylakoids as grana
– DNA
• Biochemical similarity
– cellulose cell walls
– matching enzymes
within peroxisomes
• Similar mitosis and
cytokinesis
– dissapearance of
nuclear envelope
– spindle remains till
cytokinesis
• similar sperm
• similar genes and
rRNA
• The elongation and branching of the
shoots and roots maximize their exposure
to environmental resources.
• This growth is sustained by apical
meristems, localized regions of cell
division at the tips of shoots and roots.
– Cells produced by
meristems differentiate
into various tissues,
including surface
epidermis and
internal tissues.
Fig. 29.3
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• Multicellular plant embryos develop from
zygotes that are retained within tissues of
the female parent.
• This distinction is the basis for a term for
all land plants, embryophytes.
Fig. 29.4
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• All land plants show alternation of
generations in which two multicellular
body forms alternate.
– This life cycle also occurs in various algae.
– However, alternation of generation does not
occur in the charophyceans, the algae most
closely related to land plants.
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• One of the multicellular bodies is called
the gametophyte with haploid cells.
– Gametophytes produce gametes, egg and
sperm.
– Fusion of egg and
sperm during
fertilization
form a diploid
zygote.
Fig. 29.6
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The cuticle is a secondary product
produced on the surface of leaves
to prevent dessication
The stomata is
an adaptation to
let in carbon
dioxide into the
leaf
Adaptations to Terrestrial Life
•
•
•
•
•
•
Stomata
Cuticle
lignin
sporopollenin
gametangia p548
embryophytes
• vascular tissue p555
• seeds
• flowers
• The traditional scheme includes only the
bryophytes, pteridophytes, gymnosperms,
and angiosperms in the kingdom Plantae.
• Others expand the
boundaries to include
charophyceans and
some relatives in
the kingdom
Streptophyta.
• Still others include all
chlorophytes in the
kingdom
Fig. 29.14
Viridiplantae.
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Homologies between
Charophytes and Plants
• Homologous
chloroplasts
– chlorophyll b, betacarotene
– thylakoids as grana
– DNA
• Biochemical similarity
– cellulose cell walls
– matching enzymes
within peroxisomes
• Similar mitosis and
cytokinesis
– dissapearance of
nuclear envelope
– spindle remains till
cytokinesis
• similar sperm
• similar genes and
rRNA
Introduction
• The seedless vascular plants, the
pteridophytes consists of two modern
phyla:
– phylum Lycophyta - lycophytes
– phylum Pterophyta - ferns, whisk ferns, and
horsetails
• These phyla probably
evolved from different
ancestors among the
early vascular plants.
Fig. 29.21
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Adaptation of Vascular Plants
• Root systems
– absorbs water and
minerals
• Aerial shoot systems
and leaves
– for photosynthesis
• Conducting tissue
– xylem and phloem
• Lignin
– to strengthen and
support cellulose cell
walls
• Sporophyte is the
dominant stage
• Branching in
Sporangia
– increases the # of
spores
1. Pteridophytes provide
clues to the evolution of
roots and leaves
• Most pteridophytes have true roots with
lignified vascular tissue.
• These roots appear to have evolved from
the lowermost, subterranean portions of
stems of ancient vascular plants.
– It is still uncertain if the roots of seed plants
arose independently or are homologous to
pteridophyte roots.
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2. A sporophyte-dominant
life cycle evolved in
seedless vascular plants
• From the early vascular plants to the
modern vascular plants, the sporophyte
generation is the larger and more complex
plant.
– For example, the leafy fern plants that you are
familiar with are sporophytes.
– The gametophytes are tiny plants that grow
on or just below the soil surface.
– This reduction in the size of the gametophytes
is even more extreme in seed plants.
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Most ferns are
homosporous
The gametophyte is
bisexual producing
both sperm and eggs
Seedless Vascular Plants
• Lycophyte
• Horsetails (Sphenophyta)
• Ferns (Pterophyta)
Introduction
• The evolution of plants is highlighted by two
important landmarks:
(1) the evolution of seeds, which lead to the
gymnosperms and angiosperms, the plants that
dominate most modern landscapes
(2) the emergence of the importance of seed
plants to animals, specifically to humans.
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• Agriculture, the cultivation and harvest of
plants (primarily seed plants), began
approximately 10,000 years ago in Asia,
Europe, and the Americas.
– This was the single most important cultural
change in the history of humanity, for it made
possible the transition from hunter-gather
societies to permanent settlements.
• The seeds and other adaptations of
gymnosperms and angiosperms enhanced
the ability of plants to survive and
reproduce in diverse terrestrial
environments.
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1. Reduction of the gametophyte
continued with the evolution of seed
plants
• An important distinction between mosses
and other bryophytes and ferns and other
seedless vascular plants is a gametophytedominated life cycle for bryophytes and a
sporophyte-dominant life cycle for seedless
vascular plants.
• Continuing that trend, the gametophytes of
seed plants are even more reduced than
those of seedless vascular plants such as
ferns.
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Microscopic
• For the gametophyte to exist within the
sporophyte has required extreme
miniaturization of the gametophyte of seed
plants.
• The gametophytes of seedless vascular plants
are small but visible to the unaided eye, while
those of seed plants are microscopic.
Fig. 30.1
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• An ovule consists of integuments,
megaspore, and megasporangium.
– A female gametophyte develops inside a
megaspore and produces one or more egg
cells.
– A fertilized egg develops into a sporophyte
embryo.
– The whole ovule develops into a seed.
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Fig. 30.2
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• Conifers include pines, firs, spruces,
larches, yews, junipers, cedars, cypresses,
and redwoods.
Fig. 30.8
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Gymnosperm
only have
tracheids - no
vessels
Vessels form
contiunous tubes and
thus are more
specialized for
transport of water and
less for support.
The thick
lignified xylem
cell helps in
support
1. Systematists are identifying
the angiosperm clades
• All angiosperms are placed in a single
phylum, the phylum Anthophyta.
• As late as the 1990s, most plant taxonomists
divided the angiosperms into two main
classes, the monocots and the dicots.
– Most monocots have leaves with parallel veins,
while most dicots have netlike venation.
• Recent systematic analyses have upheld the
monocots as a monophyletic group.
– They include lilies, orchids, yuccas, grasses, and
Copyright
grains.
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Monocot
Dicot
one embryonic leaf - cotyledon
two embryonic leaves - cotyledons
does not have vascular cambium and
secondary growth
has vascular cambium and secondary growth
scattered vascular bundles
leaves have parallel venation
no petioles
flower parts in multiples of three
vascular tissue arranged in circular bundles
leaves have netted venation
has petioles
flower parts in multiples of four or five
• Refinements in vascular tissue, especially
xylem, probably played a role in the
enormous success of angiosperms in
diverse terrestrial habitats.
– Like gymnosperms, angiosperms have long, tapered
tracheids that function for support and water transport.
– Angiosperms also have
fibers cells, specialized
for support, and vessel
elements (in most
angiosperms) that
develop into xylem
vessels for efficient
water transport. Fig. 30.12
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3. Fruits help disperse the
seeds of angiosperms
• A fruit is a mature ovary.
– As seeds develop from ovules after fertilization,
the wall of the ovary thickens to form the fruit.
– Fruits protect dormant seeds and/or aid in their
dispersal.
Fig. 30.15
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• The life cycle of an angiosperm begins with
the formation of a mature flower on a
sporophyte plant and culminates in a
germinating seed.
Fig. 30.17
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Ovule turns into
embryo sac
Female gametophyte
8 nuclei found
in embryo sac
• When the pollen tube reaches the micropyle, a
pore in the integuments of the ovule, it discharges
two sperm cells into the female gametophyte.
(7) In a process known as double
fertilization, one sperm unites with the egg
to form a diploid zygote and the other fuses
with two nuclei in the large center cell of the
female gametophyte.
(8) The zygote develops into a sporophyte
embryo packaged with food and surrounded
by a seed coat.
– The embryo has a rudimentary root and one or
two seed leaves, the cotyledons.
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CHAPTER 31
FUNGI
Section A: Introduction to the Fungi
1. Absorptive nutrition enables fungi to live as decomposers and symbionts
2. Extensive surface area and rapid growth adapt fungi for absorptive
nutrition
3. Fungi disperse and reproduce by releasing spores that are produced either
sexually or asexually
4. Many fungi have a heterokaryotic stage
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Introduction
• Ecosystems would be in trouble without fungi
to decompose dead organisms, fallen leaves,
feces, and other organic materials.
– This decomposition recycles vital chemical
elements back to the environment in forms other
organisms can assimilate.
• Most plants depend on mutualistic fungi that
help their roots absorb minerals and water
from the soil.
• Human have cultivated fungi for centuries for
food, to produce antibiotics and other drugs,
to make bread rise, and to ferment beer and
1. Absorptive nutrition enables
fungi to live as decomposers and
symbionts
• Fungi are heterotrophs that acquire their
nutrients by absorption.
– They absorb small organic molecules from the
surrounding medium.
– Exoenzymes, powerful hydrolytic enzymes
secreted by the fungus, digest food outside its
body to simpler compounds that the fungus can
absorb and use. Extracellular digestion.
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• The absorptive mode of nutrition is
associated with the ecological roles of fungi
as decomposers (saprobes), parasites, or
mutualistic symbionts.
– Saprobic fungi absorb nutrients from nonliving
organisms.
– Parasitic fungi absorb nutrients from the cells
of living hosts.
• Some parasitic fungi, including some that infect
humans and plants, are pathogenic.
– Mutualistic fungi also absorb nutrients from a
host organism, but they reciprocate with
functions that benefit their partner in some
way.
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2. Extensive surface area and
rapid growth adapt fungi for
absorptive nutrition
• The vegetative bodies of most fungi are
constructed of tiny filaments
called hyphae
that form an
interwoven
mat called a
mycelium.
Fig. 31.1
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• Most fungi are multicellular with hyphae
divided into cells by cross walls, or septa.
– These generally have pores large enough for
ribosomes, mitochondria, and even nuclei to
flow from cell to cell.
• Fungi that lack septa, coenocytic fungi,
consist of a continuous cytoplasmic mass
with hundreds or thousands of nuclei.
• This results from
repeated nuclear
division without
cytoplasmic
division.
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Fig. 30.2a & b
• Parasitic fungi usually have some
hyphae modified as haustoria, nutrientabsorbing hyphal tips that penetrate the
tissues of their host.
• Some fungi even have hyphae adapted for preying
on animals.
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Inc., &
publishing
as Benjamin Cummings
Fig 30.2c
d
2. Phylum Zygomycota: Zygote
fungi form resistant
structures during sexual
reproduction
• Most of the 600 zygomycete, or zygote
fungi, are terrestrial, living in soil or on
decaying plant and animal material.
• One zygomycete group form mycorrhizae,
mutualistic associations with the roots of
plants.
• Zygomycete hyphae are coenocytic, with
septa found only in reproductive structures.
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3. Phylum Ascomycota: Sac fungi
produce sexual spores in saclike
asci
• Mycologists have described over 60,000
species of ascomycetes, or sac fungi.
• They range in size
and complexity
from unicellular
yeasts to elaborate
cup fungi and
morels.
Fig. 31.9
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• Ascomycetes are characterized by an extensive
heterokaryotic stage during the formation of
Asexual
spores
ascocarps.
2 Haploid
Fruiting
mating types
body
Sexual
spores
Fig. 31.10
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4. Phylum Basidiomycota: Club
fungi have long-lived dikaryotic
mycelia
• Approximately 25,000 fungi, including
mushrooms, shelf fungi, puffballs, and rusts,
are classified in the phylum Basidiomycota.
Fig. 31.11
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• The life cycle of a club fungus usually includes a
long-lived dikaryotic mycelium.
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Fig. 31.12
Chap 32 Animal Evolution
(3) The Bilateria can be divided by the
presence or absence of a body cavity (a
fluid-filled space separating the digestive
tract from the outer body wall) and by the
structure the body cavity.
• Acoelomates (the phylum
Platyhelminthes) have a solid body and
lack a body cavity.
Fig. 32.6a
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• In some organisms, there is a body cavity,
but it is not completely lined by mesoderm.
– This is termed a pseudocoelom.
– These pseudocoelomates include the rotifers
(phylum Rotifera) and the roundworms (phylum
Nematoda).
Fig. 32.6b
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• Coelomates are organisms with a true
coelom, a fluid-filled body cavity
completely lined by mesoderm.
– The inner and outer layers of tissue that
surround the cavity connect dorsally and
ventrally to form mesenteries, which suspend
the internal organs.
Fig. 32.6b
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Mantle secretes
the shell
Radula is used
for rasping food
off of surfaces,
but can be
modified to bore
holes or tear
apart tough
animal tissue
Has trochophore
larvae a type of
ciliated larvae
They lack true
segmentation
Annelids have a true coelom which allows for easier fluid
movement between organs
They have body segmentation each segment can become
specialized
closed circulatory system with
hearts- blood with hemoglobin
excretory tubes called
metanephridia collects wastes
from the blood through a funnel
called a nephrostome and
dumps it outside through
nephridia pores.
Insecta is the largest class
3 body parts with 3 pairs of
legs
two pair of wings
nitrogenous waste excreted
through Malpighian tubules
gas exchange through tracheal
tubes
mandibles (jaws)
Echinoderms
coelomates
Echinoderms have water entering
into a madreporite down a water
vascular system that operates
tube feet
deuterostomes
They are
capable of
everting their
stomach
through their
mouth - either
dumping the
contents or
digesting
something
outside of its
body
Deuterostomes
Mouth forms later
(second)
Forms ANUS
first
• Many protostomes undergo spiral
cleavage, in which planes of cell division
are diagonal to the vertical axis of the
embryo.
– Some protostomes also show determinate
cleavage where the fate of each embryonic
cell is determined early in development.
• The zygotes of many deuterostomes
undergo radial cleavage in which the
cleavage planes are parallel or
perpendicular to the vertical egg axis.
– Most deuterostomes show indeterminate
cleavage whereby each cell in the early
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