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REVIEW MATERIAL
The following information was produced by
combining information from the state
department of education website.
Five Content Domains
1. Cells
2. Organisms
3. Genetics
4. Ecology
5. Evolution
Content Domain # 1
Cells
• Test questions in this content domain will measure your
• knowledge of cell structure and organization within the
cell. The questions will assess your understanding of and
ability to:
Differentiate between prokaryotic and eukaryotic cells
Comprehend the importance of homeostasis
Characteristics of enzymes
Characteristics of the four major biomolecules
Content Domain # 1
Cells
Unicellular VS. Multicellular
Eukaryotic VS. Prokaryotic
Content Domain # 1
Cells
LIVING VS. NONLIVING
Common Characteristics of living organisms:
• Organisms require food for energy to carry out life
processes.
• Organisms use energy to maintain homeostasis, a
balance of internal conditions.
• Organisms respond to stimuli in their environment.
• Organisms grow and develop.
• Organisms reproduce similar offspring.
• Organisms pass genetic information to their offspring.
• Organisms are made of cells.
Content Domain # 1
Cells
Cells must have boundaries.
• Cells have plasma membranes that serve as a boundary
between the cell and its external environment. The
plasma membrane is flexible and allows the cell to vary
its shape if necessary. It controls the movement of
materials entering and exiting the cell. The plasma
membrane also helps maintain a chemical balance within
the cell.
• An additional boundary outside of the plasma membrane
is the cell wall. The cell wall is thicker than the plasma
membrane and inflexible. It protects the cell and gives
the cell its shape. Plants, fungi, most bacteria, and a few
protists have cell walls. Animal cells do not have cell
walls.
Content Domain # 1
Cells
Organelles = membrane bound structures within eukaryotic
cells that perform certain functions
Some Common Cellular Organelles:
Chloroplasts
Golgi Bodies
Ribosomes
Mitochondria
Nucleus
Vacuoles
Lysosomes
Endoplasmic Reticulum
Be able to identify the functions of the organelles above.
Content Domain # 1
Cells
Homeostasis = the ability to maintain balance
The function of the plasma membrane is to control
what comes into and out of a cell.
The plasma membrane is selectively permeable.
Content Domain # 1
Cells
Passive Transport = movement of substances across the
plasma membrane without the use of cell’s energy;
3 Types:
• Diffusion = movement of substances across the plasma
membrane from an area of high concentration to an area
of low concentration
• Osmosis = diffusion of water molecules through a
selectively permeable membrane from an area of high
concentration to low water concentration
• Facilitated Diffusion = diffusion with the help of transport
proteins or carrier molecules
Content Domain # 1
Cells
Active Transport = movement of materials across cells
membranes requiring energy; It requires the use of the
cell’s energy and carrier molecules to move substances
from low concentration to high concentration; 2 Types:
• Endocytosis = a process in which a cell surrounds and
takes in material from its environment
• Exocytosis = a process by which materials leave the cell
Content Domain # 1
Cells
• Hypotonic Solution = when an animal cell is placed in a
solution that has a lower concentration of the dissolved
substance than the cell, then water moves into the cell
and the cell may burst
• Hypertonic Solution = when an animal cell is placed in a
solution that has a higher concentration of the dissolved
substance, then the cell loses water and shrivels
• Isotonic Solution = when an animal cell is placed in a
solution that has the same concentration of the dissolved
substance as the cell, then there is no movement across
the plasma membrane
Content Domain # 1
Cells
All cells maintain, increase, and decrease the concentration
of substances by developing metabolic pathways. A
metabolic pathway is an orderly sequence of reactions with
specific enzymes that act at each step along the way.
Enzymes are catalytic molecules. That is, they speed up
specific reactions without being used up in the reaction.
Enzymes are proteins.
Enzymes have four special features in common:
• 1. They do not make processes happen that would not take place on
their own. They just make the processes take place faster!
• 2. Enzymes are not permanently altered or used up in reactions.
• 3. The same enzyme works for the forward and reverse directions of
a reaction.
• 4. Each enzyme is highly selective about its substrate.
Content Domain # 1
Cells
Substrates are molecules which a specific enzyme can
chemically recognize and to which it can bind. Substrates
undergo chemical changes to form new substances called
products.
Each substrate fits into an area of the enzyme called the active
site. It is like a lock-and-key mechanism. Once the
enzyme-substrate complex is together, the enzyme holds the
substrate in a position where the reaction can occur.
• Once the reaction is complete, the enzyme unlocks the
product and the enzyme is free to facilitate another reaction.
• The rate of a reaction depends in part on the concentration of
the enzyme. If the enzyme is diluted, its concentration is
lowered, which slows the reaction rate
Activation Energy = energy required to get a reaction going
Content Domain # 1
Cells
Organic Compounds = class of compounds made of a carbon-hydrogen
base; 4 Types of Organic Compounds:
(1) Carbohydrates = Major source of energy
• Ratio of carbon, hydrogen, and oxygen atoms are 1:2:1
• Three classes of carbohydrates: monosaccharides,
disaccharides, & polysaccharides
• Examples: glucose, sucrose, starch, and cellulose
(2) Lipids = Provide insulation, store energy, and make membranes
• Building Blocks are 3 fatty acids and 1 glycerol
• Examples: fats, oils, and waxes
(3) Proteins = Form structures of living things; Enzymes
• Building Blocks are Amino Acids
• Composed of Carbon, Hydrogen, Oxygen, & Nitrogen
(4) Nucleic Acids = contain information that organisms need to live
• Complex macromolecules that store information in cells in
the form of a code
• Building Blocks are nucleotides
• Examples: DNA & RNA
Content Domain # 2
Organisms
Test questions in this content domain will measure your
understanding of the relationship between single-cell and
multi-cellular organisms and the increasing complexity of
systems.
The questions will also measure your ability to trace the
development of the classification of organisms according to
The six kingdom model.
This domain is based on the followingstandards:
• Energy is needed by all organisms to carry out processes
• Understanding the binomial nomenclature system and its
basis
Content Domain # 2
Organisms
Energy is needed by all organisms to carry out processes.
All life on earth depends on the flow of energy. The
number one source of this energy is the sun.
The process of photosynthesis supports almost all life on
Earth directly or indirectly.
ATP (Adenosine Triphosphate) is a special molecule that stores and
releases energy in its bonds when the cell needs it.
ATP/ADP Cycle:
ATP  ADP + P + energy
Endergonic Reactions = chemical reactions in which the products have
more total energy and more free energy than did the reactants. They
require the input of energy from another source before they can take
place.
Content Domain # 2
Organisms
Photosynthesis = process by which autotrophs trap energy from the sun
and use this energy to build carbohydrates. The pigment chlorophyll
is the key to this process.
Photosynthesis:
6CO2 + 6H2O + Sunlight  C6H12O6 + 6O2
Two Main Reactions of Photosynthesis:
1. Light Reactions—These reactions split water molecules, providing
hydrogen and an energy source for the Calvin cycle. Oxygen is given
off. Takes place in the thylakoids (grana) of the chloroplast.
2. Calvin cycle/Dark Reactions—the series of reactions that form simple
sugars using carbon dioxide and hydrogen from water. It takes place
in the stroma of the chloroplast.
The light reaction is the photo part of photosynthesis.
The Calvin cycle is the synthesis part of photosynthesis.
Content Domain # 2
Organisms
Consumers use carbohydrate energy for their own life
processes. One way they use carbohydrate energy is
through the process of cellular respiration.
Cellular Respiration:
C6H12O6 + 6O2  6CO2 + 6H2O + ATP
Content Domain # 2
Organisms
• Classification is the grouping of objects based on similarities.
• Aristotle was the first to use the classification system. He
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classified living things into two categories: plants and animals
Linnaeus based his classification on characteristics of
organisms that were similar.
Linnaeus also developed a two word system used to identify
species called binomial nomenclature. The first word is the
genus and is capitalized and the second word is the species
and is never capitalized.
Ex. White Oak = Quercus alba or Quercus alba
Taxonomy is the branch of biology dealing with the grouping
and naming of organisms.
A taxnomist is a person who studies taxonomy.
Content Domain # 2
Organisms
The Six Kingdoms
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Eubacteria (true bacteria)
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prokaryotic, microscopic, & unicellular
Archaebacteria (ancient bacteria)
prokaryotic, microscopic, & unicellular; found in extreme
environments
Protists
eukaryotic, unicellular & multicellular
Fungi
eukaryotic, unicellular & multicellular, heterotrophic
Plants
multicellular, eukaryotic, autotrophic
Animals
multicellular, eukaryotic, heterotrophic
Content Domain # 2
Organisms
Levels of Classification:
Kingdom
Phylum
Class
Order
Family
Genus
Species
(Kids Prefer Coke Over Fanta Grape Soda)
Content Domain # 2
Organisms
Example of Classification of largemouth bass.
Content Domain # 3
Genetics
Test questions in this content domain will measure your ability to
understand how biological traits are passed on to successive
generations.
Your knowledge will be tested according to the following standards:
• Distinguish between DNA and RNA
• Explain the role of DNA in storing and transmitting cellular
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information
Using Mendel’s laws, explain the role of meiosis in reproductive
variability
Describe the relationships between changes in DNA and appearance
of new traits
Compare advantages of sexual and asexual reproduction in different
situations
Examine the use of DNA technology in forensics, medicine, and
agriculture
Content Domain # 3
Genetics
DNA & RNA
• Nucleic Acids composed of nucleotides
• Nucleotides consist of a sugar, a Nitrogen base, and a phosphate group
DNA
RNA
Double Stranded
Single Stranded
Deoxyribose Sugar
Ribose Sugar
Adenine, Guanine, Cytosine, & Thymine
Adenine, Guanine, Cytosine, & Uracil
Replication = process of copying the DNA molecule in the nucleus
Transcription = process of mRNA copying the DNA strand in the nucleus
Translation = process occurring at the ribosomes where the mRNA is translated into
a protein; mRNA codons must join with the correct anticodon on the tRNA
Content Domain # 3
Genetics
Genetics = branch of biology that deals with heredity
Gregor Mendel = father of genetics who worked with pea plants
Some Genetic Terms:
Allele
Dihybrid
Recessive
Phenotype
Heterozygous
Dominant
Monohybrid
Gene
Homozygous
Genotype
Trait
Law of Dominance = dominant allele will prevent the recessive allele
from being expressed
Law of Segregation = gene pairs separate when gametes are formed
so each gamete has only one allele for each gene pair
Law of Independent Assortment = states that different pairs of genes
separate independently of each other when gametes are formed
Content Domain # 3
Genetics
Punnett Squares = predict the results of genetic crosses
Example: In rabbits, black fur (B) is dominant over white fur (b). If one
parent rabbit is heterozygous (Bb) and the other parent rabbit is
homozygous white (bb), what is the probability of producing an
offspring with white fur?
Crossing Over = occurs during meiosis and leads to greater genetic variation
Mutation = sudden change in the genetic code caused by mutagens
Nondisjunction = failure of chromosomes to separate during meiosis (ex. Down’s
Syndrome)
Content Domain # 3
Genetics
Cell Cycle = Interphase + Mitosis + Cytokinesis
Interphase = the longest phase during which
growth,metabolism, and preparation for division occur
Mitosis= division of the nucleus of the cell
• Prophase = duplicated chromosomes become distinct and spindle fibers
radiate across the cell
• Metaphase = duplicated chromosomes line up at the equator/center of the
cell
• Anaphase = duplicated chromosomes are pulled to opposite ends of the cell
• Telophase = nuclear membrane forms around the chromosomes at each end
of the cell; spindle fibers disappear and chromosomes become less distinct
Cytokinesis = division of the cytoplasm; two daughter cells are produced
Content Domain # 3
Genetics
Cell Division produces two new cells, each with the same number of
chromosomes as the original cell. These are diploid cells.
Human diploid cells have 46 chromosomes or 23 homologous
chromosomes.
Cell division in unicellular organisms allows them to duplicate themselves
through asexual reproduction
Cell division in multicellular organisms allows them to grow and
develop.
Meiosis = process in which gametes, or sex cells, are produced
**This is the
process that forms 4
sperm cells OR 1
egg and 3 polar
bodies
Content Domain # 3
Genetics
Genetic Engineering (aka. Biotechnology) = process
of transferring a gene from one organism to
another
Ex. The gene for human insulin is transferred into a
bacterium. The bacterium will the use the
“recombined” genetic code to produce human
insulin. This is how human insulin is massproduced.
Content Domain # 4
Ecology
Test questions in this content domain will measure your ability to
explain the interrelationships between organisms and their
environments. Your answers to the questions will help show your
knowledge of the following elements:
♦ Investigate the relationships among organisms, populations,
communities, ecosystems, and biomes
♦ Explain the flow of matter and energy through ecosystems
♦ Relate environmental conditions to successional changes in
ecosystems
♦ Assess human activities that influence and modify the environment:
global warming, population growth, pesticide use, water and power
consumption
♦ Relate plant adaptations, including tropisms, to the ability to survive
stressful environmental conditions
♦ Relate animal adaptations, including behaviors, to the ability to
survive stressful environmental conditions
Content Domain # 4
Ecology
Ecosystem = a self-sustaining unit of organisms and the physically distinct
environment surrounding the organisms
Ecology = the study of the interrelationships between organisms and their
environments
Ecologist = a scientist who studies ecology
Two types of environmental factors:
1. Biotic Factors = all the living organisms (plants, animals, bacteria, etc.)
2. Abiotic Factors = all the non-living factors (climate, light, soil, water)
Content Domain # 4
Ecology
Ecologists study the interactions of organisms at five main levels of
organization. Yet all the levels are interdependent on one another.
• Organisms — Ecologists will study the daily movements, feeding,
and the general behavior of an individual organism. An example
would be the Arctic fox.
• Populations — An ecologist will study the relationships between
populations and the environment, focusing on population size,
density and rate of growth.
• Communities — Ecologists will be concerned with the interactions
between the different populations in a community and the impacts
of additions to or losses of species within communities.
• Ecosystems — All biotic and abiotic factors make up the
ecosystem. Ecologists will study interactions of the biotic and abiotic
factors of an ecosystem with emphasis on factors that may disrupt
an ecosystem.
• Biosphere — This is the highest level of organization. It is here
where ecologists study the entire planet and the interaction of biotic
and abiotic factors on a global level. Examples of biosphere issues
would be global warming and human population growth.
Content Domain # 4
Ecology
Population Interactions
Population = a group of organisms of one species that live
in the same place at the same time. They compete for
food, water, mates, and other resources.
Population Density = the number of organisms living in a
given area
Community = made up of several populations interacting
with each other
Content Domain # 4
Ecology
Growth Rate = change in population size;
can be positive, negative, or zero
Exponential Growth = “J Shaped Curve”;
reproduction occurs at a greater rate
than their death rate
Logistic Growth = “S Shaped Curve”; As the
population increases, the resources that are
available become limited and the growth
of the population slows and begins to
stabilize
Content Domain # 4
Ecology
Carrying Capacity = The point at which the population
slows and begins to stabilize; density-dependent and
density-independent limiting factors help to stabilize the
population size
Content Domain # 4
Ecology
• Ecologists also study the interactions between populations and their
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physical surroundings.
An ecosystem is the interactions among the populations in a
community and the physical surroundings of the community (also
known as abiotic factors).
Terrestrial ecosystems are those found on land.
Aquatic ecosystems can be fresh or salt water.
Salt water ecosystems are also called marine ecosystems.
Marine ecosystems occupy 75% of the Earth’s surface!
Niche = the role a species plays in its community; it includes what that
organism eats, where it feeds, and how it impacts the energy flow
in an ecosystem
Habitat = the place where the organism lives
Content Domain # 4
Ecology
Ecosystems are identified by their climax community; these are known
as biomes. Biomes are the earth’s major ecosystems.
The 6 Terrestrial Biomes are listed below:
1. The tundra biome is found north of the Arctic Circle.
2. The taiga biome is found in a wide band south of the tundra.
3. The tropical rain forests are found in abundance in the Earth’s equatorial
zone.
4. Temperate deciduous forests are found in abundance throughout Europe
and the eastern United States, between the taiga and the tropical biomes.
5. Desert biomes occur largely in parts of Africa, and the southwestern United
States and in parts of Australia, South America, and Asia.
6. Grasslands cover most of South America, Africa, and Australia. Temperate
grasslands can be found in central United States, western Canada
and across southern Asia.
Content Domain # 4
Ecology
Content Domain # 4
Ecology
Content Domain # 4
Ecology
Sunlight is the main source of energy for living things.
Producers/Autotrophs = use the Sun’s energy to make their own food
Consumers/Heterotrophs = cannot make their own food
Food Chain = path of energy from producer to consumer
Trophic Level = each level of a food chain; only 10% of the
energy is transferred to the next trophic level
Food Web = all the interconnected food chains in an
ecosystem
Matter gets recycled in an ecosystem but energy does not!!
Content Domain # 4
Ecology
Pyramids—used to show how some populations will
decrease at each increasing level
Content Domain # 4
Ecology
Unlike energy, matter is recycled and it cycles from one organism to another.
Matter cannot be replenished.
Cycling of Major Nutrients:
• Hydrogen & Oxygen—Water passes from the atmosphere to the land or
water through precipitation and then eventually returns to the atmosphere
• Carbon--Found in the environment as carbon dioxide gas. From the
atmosphere, CO2 is used in photosynthesis to form sugar. Respiration and
decay are two ways that carbon returns to the atmosphere as a gas. Carbon
also returns to the atmosphere when fossil fuels are burned.
• Nitrogen--Atmospheric nitrogen makes up 78% of our air, but it is in a
nonusable form. Lightning and some bacteria are able to convert
atmospheric nitrogen into usable nitrogen-containing compounds. Plants
use these nitrates and ammonium compounds in their growth. Herbivores
eat the plants and convert nitrogen-containing plant proteins into nitrogencontaining animal proteins. Organisms return nitrogen to the atmosphere
when they die and decay.
• Phosphorus--Phosphorus cycles through the environment in two ways.
Plants get phosphorus from the soil. Animals get phosphorus from the
plants they eat. When the animals die, they decompose and the phosphorus
is returned to the soil. The other way that phosphorus is cycled is a long
term cycle. Phosphates that are washed out to sea become incorporated
into sediments as insoluble compounds. When the sediments become
exposed, the phosphorus can be recycled again into the environment.
Content Domain # 4
Ecology
Succession = the natural change that takes place within a community
of an ecosystem; two types:
(1) Primary Succession = happens when one community is completely
destroyed and a new one emerges.
An example is the changes that take place after a volcano erupts
and the lava flow stops and cools. Eventually, primary succession
slows down and the community becomes stable. This community is
known as a climax community.
(2) Secondary Succession = occurs when a natural disaster or
human activity destroys a community. It is like primary succession,
in that the community of organisms inhabiting an area changes over
time. However, when secondary succession takes place, soil is
already present. In secondary succession, the species replacing the
pioneer species are different. It also takes less time to reach a
climax community.
Content Domain # 4
Ecology
Natural Resources = soil, plants, water, crops, animals, gas, and oil
Nonrenewable Resources = only available in limited amounts; once
they are gone, they are gone
Exs. Some metals, minerals, topsoil, and fossil fuels
Renewable Resources = a resource that is replaced or replenished by
natural processes
Extinction = complete disappearance of a species
Threatened = species that are declining rapidly
Endangered = its numbers drop so low that extinction is almost
inevitable
Content Domain # 4
Ecology
Pollution is one of the ways humans impact the environment, which is
one of the greatest threats to living things.
Pollution is the contamination of soil, water, or air and is the result of
human activity.
Pollutant = any substance that is harmful or is a waste product
Air Pollution—caused primarily by the burning of fossil fuels to produce
electricity
Common air pollutants = dust, smoke, ask, carbon monoxide, and
sulfur oxides
Particulates = particles in smoke released during burning of fossil fuels
Smog = Combination of smoke, gases, and fog; contains sulfur oxides
which reacts with water vapor in the atmosphere to produce sulfuric
acid. The sulfuric acid falls to the ground as acid rain.
Content Domain # 4
Ecology
Another form of air pollution is the increased production of carbon
dioxide.
• When fossil fuels are burned, carbon dioxide is released into the
atmosphere
• Excess carbon dioxide in the air can contribute to the greenhouse
effect which is believed to cause global warming
• Greenhouse gases trap the energy from the sun causing Earth’s
temperature to rise and radiate back into the atmosphere. The
atmosphere prevents the heat from escaping. This is the
greenhouse effect.
• Ozone Layer = surrounds the Earth and prevents lethal doses of UV
radiation from reaching organisms on Earth
• CFC’s released into the atmosphere are thinning the ozone layer
Content Domain # 4
Ecology
Water Pollution—caused by contaminants from sewers,
industries, farms, and homes which enter water
sources.
• Sewage, chemical wastes, fertilizer, and dirty wash
water can enter lakes, streams, rivers, and the oceans.
3 R’s of Conservation:
1. Reduce
2. Reuse
3. Recycle
Content Domain # 4
Ecology
All organisms have the ability to respond to their
environment, even plants. These responses are
known as tropisms.
Content Domain # 4
Ecology
How do plants control their growth in response to
environmental stimuli?
• By chemical messengers called hormones.
• Hormones are chemicals that are produced in one part of an
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organism and transfer to another part to affect the activities
of that part of the plant.
Auxins—hormones that stimulates cell elongation
Gibberellins—hormones that cause plants to grow taller,
increase rate of seed germination, and bud development
Abscisic Acid—hormone that do the opposite; they inhibit
growth and cell division; it inhibits plant growth during
times of stress
Content Domain # 4
Ecology
Plant Adaptations:
• Seeds going dormant in unfavorable conditions
• Roots and stems are modified into storage organs
• Trees dropping their leaves
• Waxy coating on leaves to prevent evaporation
• Seeds with special structures for dispersal purposes
Behavior = anything an animal does in response to a stimuli in its
environment; inheritance plays a role in this
Innate behavior = inherited behavior of animals; includes automaticn
responses and instinctive behaviors
Reflexes = simple, automatic responses that require no thinking at all
Instincts = complex pattern of innate behaviors, they may take longer
than reflexes. Ex. Animal’s courtship behavior
Content Domain # 4
Ecology
Territory = a physical space that contains
the breeding grounds, feeding area, shelter,
or potential mates of an animal
Migration = instinctive, seasonal movement of a species
Hibernation = physiological changes that reduces the
animal’s need for energy; body temperature drops, oxygen
consumption decreases, and breathing rate decreases,
Estivation = state in which animals reduce the rate of their
metabolism due to extreme heat, lack of food, or long
periods of drought
Content Domain # 4
Ecology
• Learned Behavior is a result of previous
experiences of an animal. It has a survival
value because it allows an animals to
change their behavior in a changing
environment.
• Habituation occurs when an animal is repeatedly
given a stimulus that is not harmful and does not
have a negative impact on the animal.
• Imprinting is another form of a learned behavior. An
example is when an animal returns to the place of its birth
to lays its eggs.
Content Domain # 4
Ecology
Adaptations for Defense
Mechanical Defense is incorporated into the physical
structure of the organism.
Exs. Using claws, stingers, shells, or liquid ink from octopus
Chemical Defense occurs when the animal produces
stinging sensations, paralysis, poisoning, or just a bad taste.
Ex. Poisons, chemicals, camouflage
Content Domain # 4
Ecology
Nutrient Exclusion = some plants are not worth eating
because their tissues are lacking sufficient amount of
nutrients.
Camouflage = involves colors and patterns that enable the
organism to blend into its environment
• Cryptic Coloration = when an organism has the same color
or pattern as its background
• Disruptive Coloration = An organism’s silhouette is broken up by color
patterns.
• Countershading = when an organism is two toned. Light and dark
colors redue the visual cues to predators. Ex. Fish dark on top but light
on bottom
Content Domain # 5
Evolution
Test questions in this content domain will measure your
knowledge and understanding of the role of natural
selection in the development of the theory of evolution.
The questions will assess your understanding of and
ability to:
♦ Trace the history of the theory
♦ Explain the history of life in terms of biodiversity,
ancestry, and the rates of evolution
♦ Explain how fossil and biochemical evidence support the
theory
♦ Relate natural selection to changes in organisms
♦ Recognize the role of evolution to biological resistance
Content Domain # 5
Evolution
• From all of Darwin’s observations while on the HMS Beagle two
central concepts became the basis of his theory of evolution…
1. Variations within a species were dependent on the environment
 Adaptations are genetically coded traits that occur in organisms and
enable them to be more successful in their environment
2. The organisms on the Galapagos Islands had become geographically
separated from one another.
 Reproductive Isolation- no interbreeding between organisms of the
same species because of differences in courtship/mating behaviors,
geographic location. or reproduction times.
 Speciation- the evolution of a new species that occurs when
interbreeding happens, or when the production of fertile offspring is
prevented.
Content Domain # 5
Evolution
• Darwin did not take genetics into account when
developing his theory (After the rediscovery of
Mendel’s work, scientists connected the concepts
of natural selection and genetics- population
genetics.)
• Natural selection is a mechanism that explains
changes in a population that occur when
organisms with favorable variations for that
particular environment survive, reproduce and
pass these variations on to the next generation.
Content Domain # 5
Evolution
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Patterns of Evolution
Mass Extinctions — natural catastrophes may wipe out many species and
ecological systems at once. This allows new species to evolve.
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Adaptive Radiation — is when one species evolves into several species
that live in different ways.
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Convergent Evolution — when several unrelated species evolve to
resemble each other since they live in similar environments.
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Coevolution — when evolutionary change in one organism causes a
change in another organism. This is due to the interactions between the
two species over a long period of time.
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Gradualism – when evolution occurs over a long period of time and that
adaptive changes accumulate slowly
Content Domain # 5
Evolution
• Biodiversity is the variety of organisms, their genetic information,
and the biological communities in which they live. Researchers use
three different terms when talking about biodiversity:
• Ecosystem diversity includes the variety of habitats, living
communities, and ecological processes in the living world.
• Species diversity includes the vast number of different organisms
on Earth.
• Genetic diversity refers to the sum total of all the different forms
of genetic information carried by all living organisms on Earth. It
gives rise to inheritable variation, which scientists believe provides
the raw material for evolution.
Content Domain # 5
Evolution
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Evidence of Evolution
Fossil record (radioisotope dating is used to
determine the relative age of fossils)
• Geographic distribution of living species.
• Homologous body structures show the common
ancestry of related organisms.
• Similarities in early development.
Content Domain # 5
Evolution
• Stabilizing Selection- responsible for maintaining the status
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quo for the organisms genetic makeup
Directional Selection – involves changes to one phenotypic
property to a new one.
Diversifying Selection – diverse conditions that cause no
phenotype to be more successful than another
Disruptive Selection- results in disappearance of forms that
are intermediate between extreme variants that are more
adapted to the new environment
Balancing Selection – counteracts the loss of variant alleles
 Heterozygote advantage
 Frequency-dependent