Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

E
...

 evolutionary species concept (EvSC) the idea that members of a species all share a common
ancestry and a common fate
...
If doesn't specify on what scale
22
...
Pre-zygotic
 species are often behaviorally isolated : individuals only mate with other individuals based on
specific courtship rituals, songs, and others
...
Pre-zygotic isolation in plants can take the form of
incompatability b/w the incoming pollen and the receiving flower so fertilization fails
 in some animals, esp
...

This is all called lock and key : systems that require both components, whether physical or biochemical,
to match for a successful interaction to take place
...
plants from similar species may flower at different times or closely related
species may be separated by vast distances or physical features
B
...

22
...
By product of genetic divergence of separated populations
 Speciation - the development of reproductive isolation between populations - is just a byproduct of the genetic divergence of separated populations
...
two populations that have genetically diverged but not diverged
far enough for full reproductive isolation(speciation) = partially reproductively isolated (not yet
separate species but the differences b/w them are extensive enough that the hybrid offspring
they produce have reduced fertility or viability)
B
...

 Because genetic divergence is typically gradual, we find allopatric populations that have yet to
evolve even partial reproductive isolation but which have accumulated a few population specific
traits
...
become allopatric?
- dispersal : some individuals colonize a distant place, such as an island, far from the main
source population
-vicariance - a geographic barrier arises within a single population, separating it into two or
more isolated populations
...
in a specific kind of allopatric speciation known as peripatric speciation - a few
individuals from a mainland population disperse to a new location remote from the original
population and evolve separately
...

- suggests that change accumulates faster in these peripheral isolates than in the large mainland
populations, both because genetic drift is more pronounced in smaller populations and b/c the
environment may differ than the mainland that results in natural selection driving differences
b/w the two populations
...
It occurs when there are many
ecological opportunities available for exploitation
...
Co-speciation
separation can be just as complete even in the absence of geographic barriers
...
an organism that
parasitizes a single host species
...
So, the
two new parasite populations are separated from each other --> co-speciation (a process in which two
organisms speciate in response to each other and at the same time)
D
...
Gene flow negates the genetic
divergence of populations
...
So although gene flow is occurring, it does not affect the divergence of the two
populations b/c the hybrids don't survive
...
Speciation instantaneously
 instantaneous speciation are caused by hybridization b/w two species in which the offspring are
reproductively isolated from both parents
...
If the hybrid has double the
amount of genomes (double diploid) =tetraploid
...

 polyploids may be allopolyploids meaning that they are produced from hybridization of two
different species
...


22
...
Speciation with or w/o natural selection
 The genetic divergence of two populations can be entirely due to genetic drift with no role for
nat
...

 two ways in which nat
...
Nat
...

Section 13
...
Gene number is not a good predictor of biological complexity
 disconnect b/w levels of complexity and gene number
 human cells are able to do many more things with the genes they have
...
This differential gene expression
contributes to the large number of different cell types
...

 Genomes are measured in numbers of base pairs
B
...

 the disconnect b/w genome size and organismal complexity is called the C-value paradox
...
Most large eukaryotic genomes contain two
main types of noncoding DNA: highly repetitive DNA which consists of sequences present in
more than 100,000 copies per genome and moderately repetitive DNA which consists of
dispersed repeated sequences
C
...
5% of the genome codes for proteins other 97
...
In this class are
two types distinguished by length LINEs(long) and SINEs(shorter)
Chapter 23 Evolutionary Patterns
The history of descent with branching is called phylogeny
A
...
Phylogenetic Trees Provide Hypotheses
 Phylogenetics is one of two related disciplines in systematics, the study of evolutionary and
genetic relationships among organisms
...

 "groups" represent a number of member species
C
...
= sister groups
 a more technical term for group is taxon
 Classifications:
- monophyletic = all members share a single common ancestor not shared with any other
species or group of species
...
Taxonomic Classifications
 species --> genus -->family-->order-->class-->phylum-->kingdom - each more inclusive
 biologists refer to the three largest limbs of the entire tree of life as domains
23
...
Homology
 Phylogenetic trees are inferred by comparison of character states shared among different
groups of organisms
...
Characters have several observed conditions, called character states
 Character states can be similar for one of two reasons:
- the character state was present in a common ancestor of the two groups and retained over
time(common ancestry) --> homologous
- the character state independently evolved in the two groups as an adaptation to similar
environments (convergent evolution) --> analogous

B
...
Only some
homologies are useful: character states that are unique to a given species or all descendents and
the ancestor have it then cant use it to find relationships
 what we need are homologies shared by some, not all, of the members of the group under
consideration : shared derived characters, synapomorphies
 Phylogenetic reconstruction on the basis of synapomorphies is called cladistics
C
...
Molecular Data
 That amino acids at particular positions in the primary structure of a protein can be used as
characters, as can the nucleotides at specific positions along a strand of DNA
 The process is the same : compare to an outgroup
 An alternative method of reconstruction is based on distance rather than synapomorphies :
similarity (low distance) indicated the recency of common ancestry : but this is under the
assumption that the rate is constant
...
3 The Fossil Record
A
...
Fossils
 Fossils are the remains of once living organisms, preserved through time in sedimentary rocks
...
Through time, accumulating sediments harden into sedimentary
rocks
 record of marine life is more complete than land dwelling creatures
 fossils preserve the hard parts of organisms, those features that resist decay
 Organisms that lack hard parts can leave a fossil record in other ways:
- trace fossils
-molecular fossils (rarely DNA and proteins but mostly lipids like cholesterol)
 Rarely, unusual conditions preserve fossils of unexpected quality:
- 505MYA, sedimentary rock formation called Burgess Shale accumulated on a relatively deep
seafloor covering what is now British Colombia
...


C
...
then by measuring the
amounts of the unstable isotope and its stable daughter inside a mineral, they can determine
when the mineral formed
...
Fossils contain unique combinations of characters
 Archaeopteryx shows the transition form between birds and crocodiles (dinosaurs)
 Tiktaalik shows the transition: colonization of land by vertebrates (have characteristics of both
fish and crocodile)
E
...
1 The Great Apes
A
...
Fig 24
...

One line of old world monkeys gave rise to apes which are split into the lesser and great apes
...
2
 we are a member of the great ape group
B
...
As a result, the extent of the sequence difference b/w two
species is a good indication of the amount of time since last common ancestor
...
That split occurred 5-7 MYA
C
...




The members of all the different species in the lineage leading to humans are called hominins
...
early hominin, dating 4
...
2MYA)
 A # of trends can be seen: increased body size, increase in cranium and brain
 The fossil record indicates that about 2 million years ago, the hominin lineage ventured out of
Africa
...
It was from relatives of homo ergaster that our
species Homo sapiens derived
...

24
...
Studies of mitochondrial DNA
 Cann studied sequences of a segment of mitochondrial DNA from people living around the
world
...
Each
cell has many mitochondria, each carrying multiple copies of mtDNA and is much more
abundant than nuclear DNA and easier to extract
...

 2nd studies to check results used Y chromosome
...

B
...
What happened? Were they eliminated by the first pop
...
Did they interbreed?
 nothing similar in mtDNA which suggests that they did not
...

24
...
Bipedalism
 the shift from walking on four legs to walking on two was probably one of the first changes in
our lineage
...
Adult humans share characteristics to juvenile chimpanzees
 if we are so similar to chimps, how do we look diff? - the most sig
...

 one of the changes is resp
...
Human Brains
 why are our brains so big? tool use, social living (group hunting), and language
 not only was the brain expanding, it was being rewired
D
...
Ind
...
There are two different AA in humans when
compared to chimps
...
4 Human Genetic Variation
 many differences from one person to the next: genetic variation and differences in environment
 Compared to other organisms, we are not that different b/c we had little time for differences to
accumulate among regional populations and most of the variation arose before humans left
Africa
 the differences we see are products of selection
 sexual selection
 Sickle allele S (het) and G6PD(het) occur in places where malaria is common

Biology Unit Two Notes
...
1 Two Prokaryotic Domains






Bacteria and Archea, the prokaryotic domains of microscopic organisms so critical to the cycling
of carbon and other elements essential to life
...
1] the cell's DNA is present in a single circular chromosome
...
plasmid DNA is not essential for survival, but contains adaptive
genes
structural support is provided by a cell wall made of peptidoglycan, a complex polymer of
sugars and amino acids (gram pos vs gram neg)
Most bacterial cells are tiny --> diffusion, the random motion of molecules -- photosynthetic
bacteria gain the carbon dioxide they need by the diffusion of CO2 from the env into the cell and
that is also how respiring bacteria take in small organic molecules and oxygen
...
(the area increases as the square of the radius and the cell's
volume increases as the cube of the radius - as the cell size increases, becomes harder to supply
the cell)
few exceptional bacteria - Thiomargarita namibiensis (extremely large but 98% of its volume is
taken up by a large vacuole thus the distance through which nutrients move by diffusion is still
small)
some bacteria are multicellular, forming simple filaments or sheets of cells
...

Bacterial genomes are generally smaller than those of eukaryotes which is beneficial because
they can reproduce rapidly
...

Variation - can obtain new genes from distant relatives through horizontal gene transfer, a
process that is a major source of genetic diversity in bacteria
- some bacteria synthesize thin strands of membrane bound cytoplasm called pili that connect
them to other cells
...
4a]
- DNA released to the environment by cell breakdown can be taken up by other cells transformation
- Horizontal gene transfer by means of viruses is called tranduction
The Archea form a second prokaryotic domain
...
But there are differences
: Table 26
...
2 An Expanded Carbon Cycle






In photosynthetic eukaryotes, the photosynthetic reaction is oxygenic or oxygen producing
...
where most euk
...
Similarly, all respiration is aerobic or oxygen utilizing for eukaryotic
organisms
where O2 is limited or absent, other electron donors are available for photosynthesis and other
electron acceptors can be used for respiration
...

The top surface of a microbial mat - cyanobacteria (similar carbon cycle as eukaryotes)
Beneath the mat surface - O2 depleted and light reduced - carbon dioxide is still reduced to
carbs though by anoxygenic photosynthetic bacteria, harvest light energy to drive the synthesis
of carbohydrates but do not gain electrons from water and so do not generate oxygen gas
...
A notable difference
in Anoxygenic photosynthesis is it employs only a single photosystem because they use electron
donors that donate their electrons more easily than water like H2S, H2,Fe2+, AsO3
...

Organic molecules can be oxidized(respiration) in the absence of Oxygen
...
Where it is absent, NO3 -, Fe3+,
Mn4+, SO42-, and AsO43- are used as electron acceptors
...
Adv= doesnt need O2 ; Disadv=yields
less energy
...

organisms have two sources of energy: the sun(phototrophs) and chemical compounds
(chemotrophs)
...
Among bacteria and Archea:
photoheterotrophs-use the energy from sunlight and rely on organic molecules obtained from
the env as carbon source
...
Chemoautotrophic organisms also use chemical reactions to generate ATP
but unlike in Eukarya, they use inorganic molecules present in their env
...


26
...
-- by reducing oxidized sulfur compounds in respiration, microorganisms generate
the reduced sulfur compounds required for anoxygenic photosynthesis
...
They don't take up H2S directly because it
doesn't exist where oxygen is present and can be toxic
...
These reduced sulfur
compounds are then oxidized to SO4 by bactera(chemoautotrophic bacteria react H2S with O2
to obtain energy, producing sulfate or in anoxygenic photosynthesis, bacteria use electrons from
H2S to form carbs from CO2, generating sulfate as a byproduct)
...
where sulfate rather than oxygen is used as a final electron acceptor in respiration and is
reduced to H2S
...
The process of converting N2 into a
biologically useful form such as ammonia is called nitrogen fixation by bacteria
...

Anaerobic respiration completes the cycle by returning N2 to the atmosphere (some bacteria
can use nitrate as an electron acceptor in respiration) in denitrification
...


26
...
Populations subject to the same episodes of periodic selection belong
to a single species
...

most gram-positive bacteria (thick peptidoglycan walls) form a well defined branch of the
bacterial tree
molecular studies confirm that all bacteria capable of oxygenic photosynthesis form a single
branch, the cyanobacteria
...


26
...
These features were
present in the first Archaea as the early earth had little oxygen
...

They are chemoautotrophs, deriving energy from the oxidation of ammonia
...
6 The Evolutionary History


Sedimentary rocks preserve microscopic fossils of ancient bacteria, including the photosynthetic
cyanobacteria
...


Chapter 27 Eukaryotic Cells
27
...

eukaryotes can perform endocytosis and exocytosis
Fig 27
...
Membrane stability, required for
energy metabolism, is confined to the mitochondria and chloroplast
aerobic respiration in the mitochondrion and photosynthesis in chloroplast
unlike bacteria, phagocytosis can occur where enzymes break down particles into molecules
that can be processed in the mitochondria - in consequence, eukaryotes can exploit sources of
food not readily available to bacterial heterotrophs, which feed on individual molecules
...
1) meiotic cell division results in daughter cells that are genetically unique
2)in fertilization, new combinations of genes are brought together by the fusion of gametes
...
3 many single celled eukayotes normally exist in the haploid stage and reproduce
asexually by mitotic cell division(a) but with starvation and env
...
When stress goes away the zygote will undergo meiotic cell
division to reform the haploid cell
...

mutilcellular animals and plants (c and d)

27
...
This
association is called symbiosis
Chloroplasts originated as symbiotic cyanobacteria that through time became permanently
incorporated into their hosts - endosymbiosis (a symbiosis in which one partner lives within the
other)
chloroplasts are separated from the cytoplasm that surrounds them by two membranes(the
inner membrane corresponds to the cell membrane of the cyanobacterium, and the outer one is
part of the engulfing cell's plasma membrane
chloroplasts also have their own DNA
mitochondria, like chloroplasts, originated as endosymbiotic bacteria(proteobacteria)
...

where does the rest of the eukaryotic cell come from? genes of bacterial, archaeal, and purely
eukaryotic origin are present
...
7 1) Eukaryotic cells evolved from an
archaeon like prokaryote and only later incorporated the proteobacterial cell that became a
mitochondrion
...
The proteobacterium became a mitochondrion
...
3 Eukaryotic Diversity



















Domain Eukarya was divided into four kingdoms - plants, animals, fungi, and protists
...
They may be microscopic single celled organisms or the highly
visible multicelled seaweeds
...
Most are aerobic, some are anaerobic
...
9 7 superkingdoms
...
Choanoflagellates, a group of mostly
unicellular protists characterized by a ring of microvilli, fingerlike projections that form a collar
around the cell's single flagellum
...

Amoebozoa is a group of eukaryotes with amoeba like cells that move and gather food by
means of pseudopodia
...
Slime molds : haploid cells fuse to form zygotes that subsequently undergo repeated
rounds of mitosis but not cell division to form colorful, often lacy structures visible to the naked
eye
...
Plasmodia differentiate to form stalked structures called sporangia that produce
spores(Fig 27
...
Starvation causes cells to aggregate into a multicellular slug-like form which
eventually differentiates to form sporangia that produce spores(Fig 27
...
Three groups: Glaucocystophytes are
single celled algae
...
All have an unusual flagellum ( a hairy one and a smooth one)
...
Diatoms- distinctive skeletons of silica and account
for 1/2 of all primary production in the sea
...

Alveolata - dinoflagellates which form red tides, large and toxic blooms in coastal waters
...
Plasmodium, causes malaria
...


Chapter 28 Being Multicellular
28
...
2 Diffusion+Bulk Transport


Simple multicellularity properties - adhesive molecules cause adjacent cells to stick together
but there is little communication b/w cells and little differentiation of cell types
...
-coenycitic





Complex multicellularity - adhesion between cells and have specialized structures that allow
cells to communicate with one another, cellular and tissue differentiation, only a small subset of
all cells contributes to reproduction, cell or tissue loss can be lethal, 3D organization where only
some cells are in direct contact with the environment
...
6

28
...
Within epithelia, cells adhere to one
another by means of transmembrane proteins, esp
...
Epithelial cells secrete an extracellular matrix made of proteins and glycoproteins and
attach themselves to this matrix by integrins
...
Plants synthesize adhesive molecules but they are
polysaccharides called pectins
...

Communication - signaling molecules synthesized by one cell binds with a receptor molecule on
the surface of a second cell, essentially flipping a molecular switch that activates or represses
gene expression in the receptor's cell's nucleus
...
Single-celled eukaryotes also communicate with
other cells within the same species
...

While all eukaryotic cells have molecular mechanisms for communication between cells,
complex multicellular organisms have distinct cellular pathways for the movement of molecules
from one cell to another- gap junctions
...
In the earliest
organisms with 3D multicellularity, a nutrient or oxygen gradient triggered differentiation of
interior cells, causing cell differentiation of oxygen or nutrient starved interior cells

28
...
Plant and animal mechanisms
must differ because plant cells have cell walls and animal cells do not
...
The cells have no
pseudopodia or flagella and consequently, cannot move
...
10
...
Within another mm, this activity is curtailed as well
...




Animal cells - fertilized eggs undergo several rounds of mitosis to form a ball of undifferentiated
cells called a blastula
...
because animal cells can
move during development, animal embryos are not restricted to growth only from localized
regions like meristems
...
11

28
...
Our modern world of
abundant oxygen came to exist only 580-560 million years ago, about the time when fossils first
record complex multicellular organisms
...

Evolutionary-Developmental biology -Evo-devo : study of dev
...


Chapter 34 Fungi


organisms principally responsible for the decomposition of plant and animal tissues are fungi they play a critical role in cycling carbon

34
...
They secrete a diversity of
enzymes that break down complex organic molecules into simpler compounds that can be
absorbed
...

Fungi have no means of locomotion, they use the process of growth itself to find nourishment
most fungi are multicellular, consisting of highly branched filaments called hyphae which
provide fungi with a large surface area for absorbing nutrients
when fungi encounter a rich food recourse, they grow rapidly and branch repeatedly, forming a
network of branching hyphae called mycelium
In fungi, cell walls are made of chitin, the same compound as found in the exoskeletons of
insects and are thinner than plant cell walls
...

Yeasts are single celled fungi found in moist, nutrient rich environments so hyphae are
unnecessary
...
Fungi have the
advantage on a forest floor or in soil over bacteria b/c bacteria have only a limited capacity to
move while hyphal growth allows fungi to search actively through the soil
...










Fungi can also infect living tissues
...
depends on the ability of hyphae to expand into new tissues
...
of seedlings of less common species, fungal pathogens are thought to play an important
role in maintaining high levels of species diversity in tropical rain forests
...
In humans - athlete's foot and yeast infections
...

Lichens = stable associations b/w a fungus and a photosynthetic microorganism, usually a green
alga but sometimes a cyanobacterium
...
9) Lichens spread
asexually by fragmentation and sexually, at least by the fungi
...
2 Reproduction











hyphae cannot disperse over great distances so fungi produce spores that can be carried by the
wind, in water, or attached to(or within) animals
...
A
shortage of recourses is one of the cues that triggers spore formation
...
asexual spores are formed by mitotic cell division and
therefore are genetically identical to the parent
mechanisms to enhance spore dispersal - fruiting bodies
like other sexually reproducing eukaryotes, fungi have life cycles that include haploid and diploid
stages
...
13) The main difference: the fuision of
haploid cells is not immediately followed by the fusion of their nuclei
...
For mating to occur, two hypae grow together and release
enzymes that digest their cell walls at the point of contact
...
The cytoplasmic union
of two cells(plasmogamy) is not always followed by the fusion of their nuclei(karyogamy) forms heterokaryotic stage
...

Heterokaryotic cells with just two genetically distinct haploid nuclei are referred to as
dikaryotic (n+n)
...

Fungi do not have male and female gametes
...
Fertilization
can take place only b/w individuals that have different alleles at the mating type gene
...
3 Diversity













Fungi share a number of features with animals: Their motile cells have a single flagellum
attached to their posterior ends, synthesize chitin, store energy as glycogen
...
about a billion years ago
...
In some
species elongated cellular outgrowths called rhizoids penetrate into organic substrates
...
Chytrids disperse flagellated spores
...
Black bread mold Rhizopus
glomeromycetes - occur in association with plant roots, form endomycorrizae
Dikarya - includes 98% of all described fungal species; every mitotic division is accompanied by
the formation of a new septum, subgroups: ascomycetes - sac fungi, nuclear fusion and meiosis
take place in saclike cell called ascus and basidomycetes - club fungi because the nuclear fusion
and meiosis take place in a club shaped cell called a basidium
...

Cause athlete's foot and other infections
...
Ascomycete fruiting bodies =
contain both dikaryotic and haploid cells
...
8 spores are ejected after
meiosis
...
Fig 34
...
The life cycle(Fig 34
...
In addition, nuclear fusion takes place in a basidium not an ascus
...


Chapter 33 Plant Diversity
33
...
The oldest known land
plants was from 465 million years ago
...
Now, approximately 90% of plants
are angiosperms

33
...

the first plant lineages to diverge after plants moved to land
...
1
diverged before the evolution of lignified xylem
Mosses are the most widely distributed of the bryophyte lineages and the most diverse
...

Common features:
they are small- the major constraint on bryophyte size is thought to arise from their mode of
fertilization
...

they have simple bodies; some produce only a flattened photosynthetic structure called a
thallus
...

Both thalloid and leafy species=liverworts; leafy=mosses;thalloid=hornworts
These bodies represent the haploid generation
...
It is the
diploid, spore producing generation that represents a new component of the life cycle that
evolved as plants moved to land
...
In mosses and
liverworts, the sporophyte is short lived, drying out after the spores are dispersed but in
hornworts, they live as long as teh gametophyte
...
Fig 33
...
Instead, they absorb water and CO2 through their surfaces
...
Epiphytes=
plants that grow on other plants
...

Although Bryophytes are so diff
...
EX
...
Nevertheless, water and carbs can move
more throughout the plant
...

bryophytes make only a small contribution to the total biomass in most ecosystems
...
A major
component of peat bogs is sphagmum moss
...
3 Spore-Dispersing Vascular Plants

















In vascular plants, the diploid sporophyte is larger than the gametophyte and becomes capable
of supplying all of its own needs
...

Divided into two groups: Lycophytes, as well as ferns and horsetailes, disperse by spores and
rely on swimming sperm for fertilization, just as in bryophytes
...

Rhynie Cherts (Fig 33
...
These plants had no leaves, the stems had a cuticle with stomata, and a tiny cylinder
of vascular tissue ran through the center, had hairlike rooting structure
...
Fossils indicate that the leaves and roots of lycophytes evolved
independently from those of ferns, horsetails, and seed plants
...
Fig 33
...
9) but with changing climates, the large trees disappeared and only little
Isoetes was left
...

Ferns - distinctive leaves that uncoil during development from tightly wound "fiddleheads"
...
Vascular tissue allows fern
sporophytes to grow large but they do not exhibit secondary growth and therefore there are
limits to their growth
...

the radiation of polypod ferns occurred after the rise of the angiosperms - many of the fern
species present today are likely to have evolved to occupy habitats newly created by the
development of angiosperm forests
...

Azolla = aquatic fern used as a fertilizer for rice paddies b/c of its symbiotic association with
nitrogen fixing cyanobacteria
...
4 Gymnosperms


The seed and pollen are evolutionary innovations that played important roles in the success of
seed plants
...











The gymnosperms are one of two major groups of seed plants
...
15)
The presence of large cones rather than flowers marks cycads as gymnosperms
...
They form symbiotic associations with
nitrogen fixing cyanobacteria that allow them to grow in nutrient poor environments
...
Cycads are an ancient lineage, with fossils at least 280
million years old
...

Like cycads, ginkgos declined in abundance, diversity, and geographic distribution over the past
100 million years, as a result of changing climatesand angiosperm diversification
...
Most conifers are
evergreen, meaning that they retain their often needle like leaves throughout the year
...
18
...

Gnetophytes are a small group of gymnosperms made up of 3 morphologically diff
...
Fig
33
...
DNA analysis shows though, that they
are related more to conifers than angiosperms and therefore the vessels and double fertilization
evolved independently
...
5 Angiosperms










animal pollinated angiosperm populations can persist at low population densities; a second
feature of angiosperm production that makes it likely that rare species will persist is the extreme
reduction in the size of the female gametophyte
the last common ancestor of angiosperms and living gymnosperms is thought to have lived
more than 300 MYA
...

The formation of wood containing xylem vessels - most gymnosperms produce only tracheids, a
single cell type that serves both the mechanical and water transport role of the stem;
angiosperms have two cell types, allowing them to separate the functions of mechanical support
and water transport
...

monocots and eudicots make up more than 95% of angiosperm species : monocots make up
nearly a quarter of all angiosperms
...

They have one embryonic seed leaf, or cotyledon, whereas all other angiosperms have two
...
The lack of a vascular cambium has a profound impact on







the way monocots form roots - they continuously initiate new roots from their stems making
the roots similar to those found in ferns and lycophytes
...
Monocots do not produce
wood
Eudicots - appeared in fossil record 125 MYA, today making up 3/4 of all angiosperm species
...
Eudicots have two cotyledons but b/c all early
angiosperm lineages also have 2, these are the "true" dicots
...

Herbaceous eudicots - do not form woody stems; instead, the aboveground shoot dies back
each year rather than withstand a period of drought /cold
...
Annuals are unique to angiosperms and almost entirely eudicots
...
Most parasitic plants and virtually all carnivorous plants are eudicots
...
26

Chapter 30 Plant Reproduction
30
...
It was only with the evolution of pollen and seeds that plants no longer depended on
external sources of water for fertilization
...
1 two groups of green algae are most closely related to land plants
...
In animals, the multicellular body consists of diploid cells
...
Specialized cells
of the haploid body produce haploid eggs and sperm by mitosis - the egg is retained and the
sperm, released in water
...
3) The
haploid products of meiosis then disperse by swimming or by the zygote dispersing itself and
undergoing meiosis in the water
In Chara and Coleaochaete, both fertilization and dispersal take place in water
...

Ex
...
Like the algae, this moss has a photosynthetic body made of haploid
cells that forms gametes by mitotic division and in which the fusion of egg and sperm gives rise
to a diploid zygote
...
Some cells within this body undergo meiosis to form haploid spores,
cells that disperse and give rise to a new haploid generation
...
4) The resulting life cycle, in which a haploid gametophyte
and a diploid sporophyte follow one after the other, is called alternation of generations and
describes the basic life cycle of all land plants
...
The gametophyte is photosynthetically selfsufficient
...
The multicellular sporophyte enhances the ability of plants to disperse on
land
...
The sporangia
release their spores only when the air is dry
...
this wall contain
sporopollenin, a complex mixture of polymers that is resistant to environmental stress
...
Like
their ancestors, mosses and other bryophytes rely on water to transport sperm to egg
...
However, xylem and phloem occur
in the sporophyte generation --> difference: in byophytes it is the gametophyte that's the
photosynthetic generation, while in vascular plants it is the sporophyte generation that
dominates in both physical size and photosynthetic output
...
6 --> life cycle of the fern
...
As in mosses, the spores become covered by a
thick wall of sporopollenin
...

Chemical signals released by gametophytes producing females eggs stimulate gametophytes
nearby to produce male gametes that swim to the egg through a film of water
...
The union forms a diploid zygote which forms leaves and roots
that allow it to become a physiologically independent, diploid sporophyte
...

Seed Plants eliminate the req
...
Pollen grains are produced by all seed plants
...
Pollen allows the sperm producing gametophyte to be transported in the air
...
7 - life cycle of a pine tree
...
Pines produce reproductive structures called cones -- ovule cones(produce female
gametophytes and gametes) and pollen cones(produce male gametophytes and gametes) As in
ferns, the sporangia in the pollen cones contain cells that undergo meiosis, giving rise to haploid
spores whose walls contain sporopollenin
...
These are male
gametophytes which produce sperm
...

In pine, the male gametophyte consists of four cells at the time the pollen is shed from the
parent plant
...
For fertilization, it lands
on an ovule cone where the eggs are
...
Three of these spores abort
...
The female gametophyte fills the sporangium = ovule
...
Pollen must germinate and the male
gametophyte must produce a pollen tube
...
differs from spore dispersing
plants : 1) pollination-male gametes are never exposed to env
...
w sporophyte
and gametophyte is reversed fig 30
...
into a seed
...

Seed Coat, center is the embryo which is surrounded by female gametophyte
dormancy

Chapter 44 Animal Diversity
44
...

Fungi have cell walls, animals don't ; animals are also distinguished by embryos that include a
gastrula stage and by the presence of collagen
animals are closely related to choanoflagellates but differ from them in the presence of
persistent multicellularity, the formation of a gastrula, and the synthesis of collagen
...
Sponges are often very irregular in form
...
44
...

simple animals with radial symmetry are grouped together on one branch of the animal tree, in
the phylum Cnidaria
...













44
...
- enables animals to move horizontal, allows dev
...
These groups are shown in Fig
...
3
...
some animals, notably insects and earthworms, show a
striking pattern of body segmentation, but others do not
...
These animals are therefore called diploblastic
(Fig
...
4)
...

44
...

to divide bilaterian animals into the two groups shown in Fig
...
5, called protostomes (from
the Greek for “first mouth”) and deuterostomes (from the Greek for “second mouth”)
...
In deuterostomes, the blastopore becomes the anus
...
Neither do molecular sequence comparisons support the once widespread view that
segmented bodies
protostome phyla can be divided into two subgroups, the lophotrochozoans and the
ecdysozoans

44
...
44
...
The cells on the outer surface of the sponge are
tough and act as the sponge’s skin
...
Choanocyte cells have a collar of small
cilia around their flagellum, much like the cells of our closest unicellular relatives, the
choanoflagellates (Chapter 27)
...
44
...
Mesohyl is mostly noncellular, but it contains some
amoeba-like cells that function in skeleton formation and the dispersal of nutrients
...
The choanocytes that surround the interior
chamber of the sponge beat their flagella, creating a current that draws water from outside the
body, through the pores in its walls and upward through the central cavity of the sponge and
absorbed by cells lining the cavity by endocytosis
...
Have a radially
symmetrical body and a mouth with tentacles
...
The mouth of both medusa and polyp opens into a closed internal gastric
cavity, the site of extracellular digestion and excretion
...

The cnidarian body develops from a diploblastic embryo (one with two germ layers)
...
These tissues enclose a gelatinous mass called
the mesoglea (the “jelly” of jellyfish)
...
Cnidarians do not have a brain
though
...
like cnidarians, they have radial symmetry, outer epithelium and an
inner endodermis that enclose a gelatinous interior
...
Differences - use cilia for movement, secrete
adhesive molecule not a toxin, wastes go through cavity and out anus(comb jellies have an
anterior-posterior axis that cnidarians don't have which allows the gut to have specialized parts)
...
Flow through guts, mesoderm, and axial symmetry are
bilaterian animal characteristics (also use a neurotransmitter) - most complex
Most simple - placozoans : absorb organic molecules and use endocytosis, no tissues or cell
types, have cilia, use diffusion, reproduce asexually&sexually
...


44
...
protostome animals can be further divided into
two groups: the Lophotrochozoa (which include mollusks and annelid worms) and the Ecdysozoa
(which include insects and other arthropods)
...
Then, there are the mollusks, annelid worms,
and their close relatives, characterized by a type of larva called a trochophore
...

Annelid worms = earthworms which are found in soil - have a cylindrical body with distinct
segments
...
A digestive system extends














through the body from the head to an anus
...
Annelids have a fluid-filled coelom, or body cavity
...
Many annelids are predators(leeches) that
capture and ingest prey, but some, like earthworms, ingest sediment, digesting the organic
matter
...
Fig 44
...

Mollusks are the second major phylum of Locophotrozoa
...
Differences: Mollusks are distinguished by a unique
structure called the mantle that form their shells and helps with breathing/excretion
...
16 - have a head with a mouth
that contains a tooth like structure, radula
...
A neural ganglion exists and they are coelomates
...
Cephalopods are second class of mollusks = squid, octupus,
cuttlefish Fig 44
...
Bivalves are a third
group of mollusks that include oysters, clams and mussels
...

The second major group of protostomes = Ecdysoa which get their name form the process of
molting
...
Arthropods have
jointed legs and produce a exoskeleton out of chitin
...

Chelicerates are the only arthropods that lack antennae
...
They are among the first to invade land
...
Centipedes are predators and millipedes are
herbivores
...

Insects - like all arthropods, they shed their exoskeleton as they mature
...
Unlike other arthropods, all insects
have highly speciallized eggshells that can withstand desiccation and allow gas exchange
...
(Aquatic arthropods use gills, some terrestrial chelicerates have simple lungs
called book lungs) Insects make up more than 80% of all known animal species
...

Deuterostomes- the Deuterostomia (Fig
...
23) include three major phyla: Chordata
(vertebrates and closely related invertebrate animals such as sea squirts), Hemichordata (acorn
worms), and Echinodermata (sea urchins and sea stars)
...
24
...
They also have a dorsal nerve cord
...
44
...
also form distinctive skeletons made of
porous calcite, a form of calcium carbonate
...
Tube feet, small projections of the water vascular system that extend outward from
the body surface, facilitate locomotion, sensory perception, food capture, and gas exchange
...
44
...

The other great branch of the deuterostome tree is the chordates, the phylum that includes
vertebrate animals
...
Like hemichordates,
chordates all have a pharynx with pharyngeal slits (Fig
...
26)
...
The notochord, a stiff rod of collagen and other proteins, runs along the back,
providing support for the axis in some chordates
...
Also forming during early development is the neural tube, a cylinder of embryological
tissue that develops into a dorsal nerve cord
...
Chordates have a tail
Amphioxus (Fig
...
26) belongs to the cephalochordates - have many similarities to vertebrates
which suggest they are related
...

Tunicates share key features with chordate body plan during early dev
...
Has pharynx and pharyngial slits
...
4 Vertebrate Diversity





The animals known as vertebrates are named for their jointed skeleton that runs along the main
axis of the body, forming a series of hard segments collectively termed vertebrae
...
also
have a coelom and a closed circulatory system
...

Features that separate vertebrates from invertebrate chordates are the cranium(skull) and the
mandible(jaw) which permits a larger brain
...

44
...
The earliest branching craniates are the hagfish and lampreys (Fig
...
30)
...
Lampreys also have a vertebral column built of
cartilage
...
Both have gill slits
...
(Fig 44
...
This
monophyletic group includes about 800 species of sharks, rays, and chimaeras, all of which have
jaws and a skeleton made of cartilage (Fig
...
31)
...
44
...
Bony fish have a cranium, jaws, and bones
mineralized by calcium phosphate
...

44
...
Bony fish are by far the most diverse group of vertebrates
...
Second, they possess a unique gas-filled sac called a swim
bladder that permits exquisite control over their position in the water column through changes
in buoyancy
...
About a dozen
closely related species, however, have paired pectoral and pelvic fins
...
44
...
Although these animals
resemble other fish, the coelacanth and lungfish are the nearest relatives of tetrapods, fourlegged animals
...
Because the fleshy-finned fish are the closest
relatives of tetrapods, there is no monophyletic group that corresponds to our popular notion of
“fish
...

Living tetrapods include amphibians, such as frogs and salamanders; lizards, turtles,
crocodilians, and birds; and mammals
...
Some, however, like snakes and a few
amphibians and lizards, have lost their legs in the course of evolution
...
44
...
Most species have an aquatic larval
form with gills that permit breathing under water and an adult form that is terrestrial and
usually has lungs for breathing air
...

Like insects, some vertebrates evolved an egg adapted to tolerate dry conditions that
accompany life on land
...

42
...
These eggs must be fertilized internally - permits the group of vertebrates known as
amniotes to live in dry terrestrial habitats that amphibian eggs cannot tolerate
...
44
...
Most mammals, many
lizards, and some snakes have evolved live birth rather than laying eggs
...
44
...
One is
made up of mammals, and the other contains turtles, birds, and the amniotes traditionally
grouped together as reptiles
...
The earliest-branching living mammals, the monotremes,
lay eggs, like birds or lizards (Fig
...
36), but their hatched young drink milk secreted from pores
in the skin of the mother’s belly
...
The first mammals that gave birth to live young gave rise to the two major groups
of living mammals, marsupial and placental mammals
...

Most diverse mammals - bats and rodents



---