Download Flip Folder 7 Key - Madison County Schools

Flip Folder #7 - Unit 7: Evolution KEY
1) Influences on Darwin
a) Lyell**
I.
Proposed the Theory of Uniformitarianism. (“The key to the past is the present”.) The theory tries to
explain that the same geologic processes that are occurring today, also occurred in the past. These
processes helped to create, over millions of years, the geologic formations we see today. For example,
erosion, over millions of years and still today, led to the formation of the Grand Canyon.
II.
For this theory, Earth must be hundreds of millions of years old. (This also supports Darwin’s theory…
it provides enough time to pass so that we get the millions of different species to evolve.)
b) Wallace**
Had the same theory of evolution as Darwin. He spurred Darwin to actually publish his book.
c) Lamarck**
Lamarck was “off the mark” about the cause of evolution.
His theory is called Inheritance of Acquired Characteristics by means of use versus disuse (This will become
referred to as Lamarckian Evolution.)This basically states that if an organism uses a body part routinely it must
be of importance and therefore that body part will be passed on to the next generation. If an organism does not
use a body part, it will disappear over time because it must not be important. (This is the part he got wrong… if
it were true, think about body builders with their massive muscles. If it were true, their children would be born
with massive muscles, but that is not the case. Also if someone lost a leg, their children should be missing that
leg when born, as it was not being “used”. The change must occur in the DNA of a sperm or egg [gametes] to
be passed on to the next generation.)
Lamarck also makes no mention of the environment’s role in evolution. (Which he had wrong too.)
d) Cuvier**
He proposed the Theory of Catastrophism. (This theory tries to explain why organisms seem to suddenly disappear
from existence on earth, such as the extinction of the dinosaurs. Some catastrophic event must have occurred to
cause their sudden, in geologic terms, extinction to occur.)
He was a paleontologist who noticed that fossils in different sedimentary rock strata would disappear as the lowers
went up (got younger).
e) Hutton**
Hutton said “the world was puttin’ along”
He proposed the Theory of Gradualism. This theory tries to explain that that the earth must be very, very old
because in order for some processes to occur, such as mountain formation or canyon formation, it would require
enormous amounts of time.
According to the theory, Earth must be very old. This is very important to Darwin’s theory of Natural Selection
because the theory of gradualism supports the time frame needed for Natural Selection to transform species over
generations.
f) Malthus**
Thomas Malthus’s Principles of Populations
A. The book basically states that more organisms are born than nature can allow to survive.
1.
So Darwin got the idea of overpopulation (without which natural selection would not occur)
from Malthus.
B. Remember, carrying capacity? So “who” chooses… nature… based on the traits an organism
possesses. Remember variation is important.
f) Observations from Galapagos Islands
Darwin’s finches, marine iguanas long tails, blue footed boobies blue feet
2) Natural Selection
a) Explain how each of the following truths lead to natural selection**
• Overproduction
Too many organisms to survive so there is COMPETITION.
• Limited Resources
Not enough food, water, space etc. BECAUSE OF OVERPOPULATION.
• Variation in phenotypes and alleles
There is GENETIC VARIATION IN A GENE POOL due to sexual reproduction and mutations.
• Competition – Differential Survival
Occurs because of a combination of the first 3 bullets (too many of us, not enough resources, and we’re all
different). Whoever has the ADAPTATIONS that allow them to retrieve these resources most efficiently will
survive and reproduce.
• Inheritable traits
Survivors PASS ON THE GENES FOR THE ADAPTATIONS to their offspring.
• Accumulation of change
Eventually, the GENE POOL CHANGES TO HAVE A GREATER FREQUENCY OF THE ALLELES OF
THE SURVIVORS.
b) Fitness**
1) Survive Longer, 2) Reproduce more  3) Gene pool changes to be more like you
Note: Surviving IS NOT ACTUALLY NECESSARY. It is just that you survive long enough to reproduce (and the
longer your alive the more opportunities you have to reproduce).
Note: Fitness DOES NOT NECESSARILY MEAN YOU ARE BIGGER, STRONGER, ETC.
3) Evidence of Natural Selection
a) Direct Observations**
Many examples. Ex. Peppered moths.
b) Fossil Record (appearance, relative dating, absolute dating)**
Found in strata of sedimentary rock, ice, amber. Relative dating done by comparing strata they are found in
(OLDER STRATA ON BOTTOM AND YOUNGER ON TOP).
Absolute “Radiometric” dating
A. Uses the half-life of radioactive elements that accumulate in an organism over time.
B. C-14 (Used for thousands.); U-238 (Used for millions  billions.)
Relative Dating
C. Uses the different strata of rock and index fossils to establish a time line. Index Fossils are fossils that
we know a specific time period they existed. They are compared to the location or strata where we
found an “unknown” dated fossil. If the “unknown” is found above the index, the “unknown” is
younger. If the “unknown” is found below the index, the “unknown” is older. Positions are relative to
time.
c) Biogeography
study of the distribution of species and ecosystems in geographic space and through geological time.
d) Artificial Selection**
Evolution that occurs because of human interference (the evolution is “artificial”)
Natural selection occurs because of nature (environment). Artificial selection occurs because of humans.
Artificial selection occurs much faster because in nature the winner of competitions may only have a slight
reproductive advantage (takes many generations for major differences to be seen). In artificial selection, we only let
those with the adaptations we want reproduce (so it’s 100% to 0%)
Ex. Dogs or crops
e) Embryology
Embryological Homologies are seen as common stages of development that embryos go through. (Darwin wrote
about these in his book too.)
f) Molecular Record
Molecular Homologies - refers to DNA nucleotide sequences being exact in order and function. (Darwin could not
write about these, as they had not been discovered yet.)
The closer 2 different species DNA is to one another, then the closer those 2 are related.
4) Examples of Natural Selection
a) Peppered Moth
The evolution of the peppered moth is an evolutionary instance of color variation in the moth population as a
consequence of the Industrial Revolution. The concept refers to an increase in the number of dark-colored moths
due to industrial pollution, and a reciprocal decrease in the population in a clean environment.
b) Antibiotic resistance**
As more antibiotics are used, the only bacteria that survive are those that are antibiotic resistance (thus the frequency
of antibiotic resistant bacteria continues to increase).
This is because there is A VERY STRONG SELECTIVE PRESSURE AGAINST BACTERIA WHO ARE NOT
ANTIBIOTIC RESISTANT (AND STRONG SELECTIVE PRESSURE FOR BACTERIA THAT ARE).
If antibiotics were no longer used then there would be no selection for antibiotic resistant bacteria.
c) DDT resistance**
DDT was a commonly-used pesticide for insect control in the United States until it was canceled in 1972 by the
United States Environmental Protection Agency (EPA). DDT was initially used by the military in WW II to control
malaria, typhus, body lice, and bubonic plague.
DDT resistant mosquitoes increased for the same reason as the antibiotic resistant bacteria described above.
5) Convergent vs Divergent Evolution
a) Definitions**
Convergent Evolution - These species do NOT have a common ancestor. They have merely evolved to look similar
as they possess similar traits. (SAME FUNCTION, DIFFERENT ANCESTOR)
Example: Birds, bats, and moths have wings, but they did not evolve from a recent common ancestor.
Divergent Evolution – Build-up of differences between groups which can lead to the development of a new species.
In other words, two different species that evolved from the same ancestor.
b) Causes of each
Convergent Evolution - living in similar habitats / performing similar functions
Divergent Evolution - 1. moving to two different environments or 2.specializing in different areas of the same
environment
c) Analogous Structures; example
Analogous Structures:
 Structures with closely related function but do not come from the same ancestral structure
◦ Same function, different structure
 Example: Birds, bats, and moths have wings, but they did not evolve from each other.
 Caused by convergent evolution
d) Homologous Structures; example
Homologous Structures:
 Structures in different species that originated from common ancestor
 May have different function but similar structure
 Caused by divergenet evolution
6) Genetic Variation (how do the following maintain diversity?)
a) Mutations in gametes**
These create NEW ALLELES that have never been seen before. This is the only way to create NEW DNA. The only
mutations that increase variation are those in gametes because mutations in somatic cells are not passed on.
b) Heterozygote advantage –
This maintains diversity because when heterozygotes have the advantage, there will be a 25% of a recessive
baby being born with every reproduction between heterozygotes (even if the recessive trait is a disadvantage).
i. Sickle Cell and Malaria
Sickle- cell trait (“trait” is used to refer to individuals that are carriers.)
i. These individuals have resistance to Malaria because of the one recessive allele they possess but mainly
have normal red blood cells for carrying oxygen.
ii. This is referred to as the Heterozygote Advantage. They have an advantage over individuals that are
homozygous dominant or homozygous recessive. Homozygous dominant are not resistant to Malaria.
Homozygous recessive are also resistant to Malaria; BUT they have the disease to contend with.
iii.
ii. Frequency-dependent selection
Frequency-dependent selection is the term given to an evolutionary process where the fitness of a phenotype
depends on its frequency relative to other phenotypes in a given population.
In positive frequency-dependent selection, the fitness of a phenotype increases as it becomes more common.
In negative frequency-dependent selection, the fitness of a phenotype decreases as it becomes more common. This
is an example of balancing selection.
c) Sexual reproduction (crossing over, law of independent assortment, law of segregation, random fertilization)
Law of Segregation
The law of segregation is that our diploid homologous chromosomes separate into haploid gametes at the end of
metaphase (anaphase). This means heterozygous people can have homozygous kids. This is the reason why
recessive traits can be “hidden” but then show back up.
Law of Independent Assortment
We have 23 pairs of chromosomes THAT LINE UP INDEPENDENTLY of each other. The information on each
chromosome is inherited independent of the other (like hair color and eye color).
Crossover
Homologous chromosomes synapse forming a tetrad. Crossing over between homologous chromosomes occurs
here.
7) Hardy Weinberg
a) Equations with explanations**
 Equation 1: p + q = 1
o p = frequency of dominant allele
o q = frequency of recessive allele
o 1 = 100% of the population
o Equation says that there are only 2 alleles, dominant or recessive allele. These 2 alleles make up
the entire gene pool for this particular gene.
 Equation 2: p2 + 2pq + q2 = 1
o p2 = frequency of homozygous dominant (p * p)
o 2pq = frequency of heterozygous (pq OR qp – REMEMBER THE RULE OF ADDITION)
o q2 =
o 1 = 100% of the population
o Equation says that if there are only 2 alleles for a particular gene in a gene pool, p (A) and q (a),
then there are only 3 possible genotypes, p2 (AA), 2pq (Aa), q2 (aa).
b) What does it measure?**
Measures the change in allele frequency (equation 1) or gene frequency (equation 2) in a population. In other words,
it keeps track of the stability (Hardy-Weinberg Equilibrium) or change (evolution) in the gene pool.
c) Gene pool**
All the genes in a population; EVOLUTION OCCURS WHEN A POPULATION’S GENE POOL
CHANGES.
d) Hardy Weinberg Equilibrium means?**
The gene pool is not changing for that particular gene. There is no evolution.
b) 5 conditions (Violation of HW results in evolution)**
**A violation of Hardy-Weinberg results in evolution.
– Very large population
– Prevents genetic drift.
– No gene flow between populations
– Prevents immigration or emigration of alleles into/out of the gene pool.
– No mutations
– Prevents creation of new alleles (so new alleles besides just p and q – dominant and recessive).
– Random mating
– Prevents sexual selection. This means that one mate (and the mate’s reproductive adaptations) will
not be favored over the other.
– No natural selection
– Prevents one phenotype from out-competing the other variations. Prevents a variation with
selective advantage from surviving long/reproducing more.
8) Mechanisms of Evolution
a) Genetic Drift
Changes in a gene pool due to chance (has greater effect on smaller populations)
i. Founder Effect
ii) Bottleneck Effect
Decrease in population size after catastrophe may leave only certain alleles available
b) Natural Selection
Essentially, nature selects the strong traits to survive while the weak ones are “weeded out”. This is not a random
process. Nature selects the best adaptations to survive.
1) Overpopulation
2) Genetic variation
3) Competition because of a combination of 1) and 2)
4) Those with adaptations to win competition survive and reproduce.
5) The frequency of alleles in the gene pool change to have a higher frequency of the survivors (and a lower
frequency of those who lose out in the competitions).
c) Mutations
Creation of new alleles by mistakes occurring during DNA replication. It only affects evolution if these mutations
occur in the gametes.
d) Gene Flow
Immigration or emigration of alleles into/out of a population
9) Types of Selection
a) Sexual Selection
Sexual selection-form of natural selection in which individuals with certain characteristics are more likely than other
individuals to obtain mates (leads to sexual dimorphism – differences in males and females). This is different than
natural selection because it does not involve a competition for resources in the environment. These traits do not
actually have to lead to longer survival (and in lots of cases, i.e. brightly colored fish, they cause a decrease in
survival but these fish still reproduce more); therefore, they are sexual selected in evolution.
Physical Examples:
Feathers of a male peacock
Antlers of a male deer
Humans
Behavioral Examples:
Darwin Beetles Darwin Beetle Video
Blue footed Booby
Humans
b) Direction selection
 Directional Selection
favors one extreme phenotype (physical type)
This causes this particular extreme phenotype to become much more common (the look of the population is
pushed in 1 direction)
Ex. Peppered Moths
c) Disruptive selection
 Disruptive/Diversifying
Selection that favors both extreme phenotypes (physical type)
This causes extreme phenotypes to become much more common (the look of the population shows extreme
differences)
Ex. Darwin’s Finches
d) Stabilizing selection
 Stabilizing
Selection against the extreme phenotypes (physical type)
This causes average phenotype to become much more common (the look of the population is very similar and
average)
Ex. Human weight at birth
10) Macroevolution vs. Microevolution
a) Macro**
Large scale evolution. Creation of a new species. This is caused by continue microevolution in a particular manner
until enough differences build up between organisms in a population that they no longer can reproduce with one
another.
b) Micro**
Small scale evolution. Changes in alleles frequency in a gene pool. This is just changes in the phenotypes in a
population (no new species created).
c) Reproductive isolation
If 2 populations cannot reproduce for whatever reason then they can eventually become new species because of
differential environmental pressures and differential mutations between the 2 species. Exactly what it sounds like.
The 2 groups are isolated reproductively.
11) Speciation
a) Species**
Can produce viable, fertile offspring
b) Allopatric vs. Sympatric Speciation
A. Allopatric speciation – speciation that occurs because of GEOGRAPHIC ISOLATION of a population
a. Steps that lead to allopatric speciation
1. Geographical separation of species (with its gene pool) from other populations
2. No gene flow. Mutations are inevitable so the separated gene pools (from population
A and population B) will continue to have separate mutations. If there is no gene
flow, then these mutations are not transferred to the other population and the gene
pools become increasingly different.
3. Greater genetic drift (because of smaller populations)
4. Eventually, the DNA of the 2 populations becomes so different that the organisms
cannot reproduce even if they are mixed back together.
B. Sympatric speciation – Speciation that occurs with no geographic isolation.
a. This type of speciation is more rare but does occur. It occurs because there is some type of
reproductive isolation amongst the species that prevents them from breeding. Since there is no
breeding, there is no gene flow. Without gene flow, the 2 groups can accumulate differences
and eventually become a new species.
c) Polyploidy
1. For plants – This mainly occurs because of polyploidy (a condition of having abnormal chromosomal
numbers) because of cross fertilization between plants that have had meiosis go awry in the formation
of gametes.
a. Autopolyploidy - Is the result of self fertilization. (“auto = “self”; “poly”= many;
“ploidy” = “genetic content”)
b.
Allopolyploidy - Is the result of different plants cross fertilizing.
d) Sexual selection
Sexual selection can lead to speciation if the population becomes segregated due to breeding practices (the
prezygotic barriers explained next).
12) Prezygotic Barriers
a) List and explain
 Prevent a mating attempt
o Habitat isolation – Even though they’re in the same environment, they live in different
habitats. i.e. in the water or land.
o Temporal isolation – Different mating seasons or one is nocturnal while the other mates
during the day.
o Behavior isolation – Do not recognize each other’s mating dances.
 Mating is attempted but is unsuccessful
o Mechanical isolation – The “male parts and female parts” just don’t fit together.
o Gametic isolation - The sperm reaches the egg, but it is unable to penetrate the egg (so no
fertilization occurs).
13) Postzygotic Barriers
a) List and explain
 Reduced hybrid viability – The hybrid doesn’t live as long as the other parent species.
 Reduced hybrid fertility – The hybrid is viable, but cannot reproduce (i.e. donkey).
 Hybrid breakdown – The first generation hybrid is fine, but as they reproduce (2 nd generation hybrid,
3rd generation hybrid, etc.) they begin to become less and less viable.
14) Rates of speciation - Punctuated Equilibrium vs. Gradualism
a) Definitions**
Punctuated equilibrium – long periods of no change, rapid change after catastrophism
Gradualism – things change slowly, incrementally over time
b) Causes**
Punctuated equilibrium is caused any time there are many open niches. This can be after a new land area is
colonized or after a catastrophe (theory of catastrophism). Typically, when an organisms loses out in a competition it
will try to occupy another niche unsuccessfully (because other organisms already occupy it). This causes them to die
out. When there are lots of available niches, the losers of the original competition occupy a different niche (by eating
different food, moving to a different area, etc.). This means that these alternate variations of the species (and their
alternate alleles) are able to survive and reproduce. Because these organisms would no longer mingle/reproduce with
the species they lost to, there would be reproductive isolation that would eventually lead to new species.
Gradualism is caused by the slow, incremental changes that occur always as the environment uses natural selection
to specialize the species to the environment.
c) Example Cladograms
d) Adaptive radiation
i. Define
Evolution of many diverse species from one common ancestor.
Typically when few organisms occupy new area, start filling up available niches
ii. Real world example
Darwin’s Finches
Mammals after the extinction of dinosaurs
15) Phylogenetic Tree/Cladogram – Use to show the evolutionary timeline of macroevolution. Shows that is not a
linear process with a start and finish, rather it is a branching process with many intermediates.
a) Nodes
Shows ancestors from divergent evolution
b) Most recent common ancestor
Represented by the nodes
c) Relative Age
Longer divergence line = older (and vice versa)
d) Molecular vs. Morphological
Molecular = cladogram based off of DNA/amino acid similarities
Morphological = cladogram based off of homologous structures
16) Major Events in Earth’s History
a) Earth’s early environment**
a. Thick with water vapor and compounds released by volcanoes
b. Cooled and water vapor became oceans
c. NO OXYGEN – because there was no photosynthesis
a. Photosynthesis was complex so it took a while for these organisms to occur
d. Prokaryotic Life forms evolve about 3.5 Billion years ago
e. Eukaryotic Life forms evolve about 2.7 billion years ago (Remember the Endosymbiant Hypothesis?)
f. Oxygen Catastrophe or Oxygen Revolution
i. The rapid rise in atmospheric free oxygen occurred about 2.7 Billion years ago by the evolution of
Cyanobacteria in the Earth’s water bodies. (“cyano” means “blue-green”) because they were performing
photosynthesis.
ii. This caused a mass extinction of anaerobic (lacking oxygen) organisms. Oxygen was deadly to them.
b) Oxygen**
No oxygen in the early environment because there were no photosynthetic organisms to convert it to its atmospheric
gas form.
** Note: There was oxygen, but no oxygen gas (O2).
Oxygen Catastrophe or Oxygen Revolution
i.
The rapid rise in atmospheric free oxygen occurred about 2.7 Billion years ago by the evolution of
Cyanobacteria in the Earth’s water bodies. (“cyano” means “blue-green”) because they were
performing photosynthesis.
ii.
This caused a mass extinction of anaerobic (lacking oxygen) organisms. Oxygen was deadly to them.
c) Eukaryotes-Endosymbiosis
Creation of eukaryotes from 2 independent prokaryotes. Larger prokaryote engulfs smaller. The larger is benefitted
because it gets excess energy (from heat released by smaller). The smaller is benefited by protection of the bigger.
Because bacteria reproduce by binary fission, once this mutualistic relationship was formed they could choose to
reproduce simultaneously and stay together.
Created mitochondria and chloroplast. Evidence:
 Both have double membrane from endocytosis
 Both have own DNA and ribosomes. These ribosomes are very similar to prokaryotic ribosomes (and
not like other eukaryotic ribosomes).
 Both reproduce by splitting process similar to binary fission.
 Both are similar in size to bacteria.
d) Cambrian Explosion**
The Cambrian explosion, or less commonly Cambrian radiation, was the relatively short evolutionary event,
beginning around 542 million years ago in the Cambrian period, during which most major animal phyla appeared, as
indicated by the fossil record.
Lasted for about 30 million years.
e) Colonization of land**
Plants colonized land about 500 million years ago.
Benefits of living on land:
Sunlight is brighter, since it doesn't have to go through water first
Led to phototropism
More carbon dioxide in the atmosphere than in the ocean
Mineral nutrients are plentiful in the soil
Challenges of living on land:
Less water, so plants needed to avoid drying out
Lead to the need of cuticles, barks, etc.
No support against gravity
17) Major Taxons (DKPCOFGS)
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
18) Prokaryote Kingdoms (Bacteria and Archaea)
1) Archaea – prokaryotic, unicellular, can be both auto- or heterotrophic (but DO NOT have chloroplast
because they are prokaryotic), mobile
2) Bacteria - prokaryotic, unicellular, can be both auto- or heterotrophic (but DO NOT have chloroplast
because they are prokaryotic), mobile
19) Kingdom Protista
Protista – eukaryotic, mostly unicellular (some multi-), auto- or heterotrophic (they DO have chloroplast
because they are eukaryotic), mobile and non-mobile
Remember that this is the “throw away” kingdom. If it is eukaryotic but is not a plant, animal, or fungi then
it gets put into this kingdom; therefore, this group is more about how they ARE NOT like the other kingdoms
more so than that they are a lot alike one another.
20) Kingdom Fungi
Fungi – eukaryotic, multicellular, heterotrophic (do NOT INGEST food, they leach nutrients out of whatever they
grow from), non-mobile.
DECOMPOSERS
3 reasons why many fungi are generally pathogenic.
i.
Produce spores that can survive for very long periods of time in unfavorable conditions and will wait to
sprout until conditions are favorable for the adult fungi to survive
ii.
Have a branching network called hyphae that work with their roots to digest the surface they are growing
off of
iii.
Some of them can produce toxic chemicals
21) Kingdom Plantae
a. Gymnosperm
Non-Flowering, Seed producing, vascular plants. Seeds develop on modified leaves (usually cones)
Ex. Pine cones.
b. Angiosperm
Flowering, Seed producing, vascular plants. Ovary becomes fruit once the egg is fertilized.
22) Kingdom Animalia Diversity Overview
a. Types of Symmetry
Radial symmetry is all equal sections (like a pizza)
Bilateral symmetry is equal left and right side
b. Cephalization
Specialization of a “head” region. All bilateral/mobile organisms have some degree of a head. This allows the
majority of the sensory organs to be located closer to the brain. This means the process of sensory input, integration,
and motor output can occur much faster.
c. Coelom Structures
Refers to the main body cavity in most multicellular animals[1] and is positioned inside the body to surround and
contain the digestive tract and other organs.
 Endoderm is the inside tissue
 Ectoderm is the outside tissue
 Mesoderm is the middle tissue
d. Protostome /Deuterostome
The majority of coelomate invertebrates develop as protostomes ("first mouth") in which the oral end of the
animal develops from the first developmental opening, the blastopore.
In the deuterostomes ("second mouth") including Echinodermata and the ancestors of the Chordata, the oral
end of the animal develops from a second opening on the dorsal surface of the animal; the blastopore
becomes the anus.
23) Animal Phylums - Invertebrates – Characteristics**
a. Porifera**
Sponges. Rember by “porifera” and “pores”.
Simplest phylum because do not have tissues (most complex layer is cells).
They show asymmetry because each of the cells is independent of the others (so it doesn’t matter which direction
they grow).
Still considered an animal because sponges INGEST THEIR FOOD.
Cnidaria**
Cnidaria – jellyfish, sea anemone, hydra, coral. “Cnid” means stinging.
2nd most simple phylum because have tissues, but no organs
Have gastrovascular cavity instead of digestive and vascular systems.
Nematoda – Unsegmented roundworms. Example – heartworms.
b. Platyhelminthes**
Platyhelminthes – flatworms. Remember by “Flat-y-helminthes”
d. Annelids**
Annelida – segmented worms (earthworms, leeches)
c. Mollusca**
Mollusca – all soft bodies organisms that use shells (snails, clams, etc.) + squid and octopus. Most common
marine phylum (23%).
e. Arthropod**
Arthropoda –
Most common animal phylum by far (80% of all animal species because it has the class Insecta which is 70%
of all animal species).
Class Insecta (6 legs, 3 segmented body parts) vs. Class Arachnida (8 legs, 2 body parts)
f. Echinodermata**
Echinodermata – starfish, sea urchin
Echin = spiny and derm = skin
23) Chordates
Chordata – amphibians, birds, reptiles, mammals
a. 4 Chordate Characteristics
1. These are animals possessing a notochord (back bone). (These are the higher grade animals.) Remember by
chordata and cord (spinal cord)
a. Four general characteristics of all Chordates
1. They possess a notochord - This is a flexible support rod running dorsally.
2. They also possess a dorsal, hollow nerve chord. a. This structure develops into the Central Nervous System (CNS) – brain and spinal cord.
3. Pharyngeal slits -This allows water passage to bypass the digestive tract.
4. They possess a muscular post-anal tail. (This, over millions of years, has reduced to tail bones in
humans and great apes.)
b. Amphibia**
These are all tetrapods. (means “organisms with four legs”)
They are scaleless. (They must keep skin moist to breath; therefore they live in moist environments.)
They have webbed feet for swimming.
They have a three-chambered heart. Two – atriums (receives blood) and one ventricle (pumps blood out)
They must have water for eggs to be laid in, just like the fish.
They undergo complete metamorphosis.
1.
Larva—is a water herbivore; adult – is a terrestrial carnivore.
vii.
Amphibians are important environmental indicators of water quality. (Due to the eggs needing clean
water.)
1.
Acid rain and pollution are causing large species extinction in our time.
Note: All the rest of the classes listed (Reptiles, Birds, Mammals) are Amniotes -These are organisms that produce
a fluid-filled eggs that do not have to be in water.
c. Reptiles**
A.
General Characteristics of reptiles:
1.
Body covered by scales of keratin. (Prevents desiccation.)
2.
They have true lungs (possessing alveoli… small air sacs) and a three-chambered heart.
3.
They are Ectothermic - They absorb heat from the surrounding environment. (This keeps their metabolism
i.
ii.
iii.
iv.
v.
vi.
low… so they do not have to eat as often as birds and mammals.)
d. Birds**
A.
General characteristics of birds: **Characteristics that are adaptations that led to flight
1.
They have scales on the feet and face.
2.
Feathers (are modified scales of keratin) on aerodynamic wings and body. **
3.
They have hollow bones.**
4.
They lay eggs with the developing embryo inside the egg.
5.
They have a reduced number of organs. (For example, only 1 gonad.)**
6.
Toothless beak of fused keratin. (The shape dictates diet.)**
7.
Endothermic - They generate heat within from food breakdown. (They have fat tissue to help
retain the heat.)
8.
Lungs have secondary air sacs. (2x as much oxygen in one breath)**
9.
They have a four-chambered heart. (Allows for increased activity.)**
10.
They have excellent eyesight. (Most are predators) **
e. Mammals**
A.
Mammal general characteristics:
1.
They possess mammary glands in the breasts to feed the young high protein milk.
2.
They have hair of keratin and a sub-cutaneous fat layer, both act as insulation to trap heat.
(Endothermic)
3.
They have a four-chambered heart and most have a large brain capable of some level of learning.
4.
Most give live birth. This needs a placenta – connection with the mother.
5.
Different types of teeth (The organisms diet indicates the type of teeth they possess.)
a. Incisors (cut), Bicuspids (puncture), Premolars and molars (grind)
6.
Most show a high level of parental care. The number of offspring is proportional to energy spent
on rearing.
24) Hardy Weinberg Problem A researcher is working with a walking stick insect population in north eastern Kentucky. They estimate the % of
the population, by the mark-recapture method, possessing the recessive trait to be 16%. What is the frequency of the
dominate allele within the population?
q2 = 0.16
q2 = q so
0.16 = 0.4
q = 0.4
p + q = 1 (p + 0.4 =1)
p = 0.6  This is all the question asks for so you would be done here. I’m going to show the other steps for
what they could possible ask you as well.
Homozygous dominant (p2) = 0.6 * 0.6 = 0.36
Heterozygous (2pq) = 2 (0.6)(0.4) = 0.48
Homozygous recessive (q2) = This was already given = 0.16  (0.4 * 0.4)