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“Principles of Evolution” Common Assessment
Review Questions
1.
Give a description of natural selection. Give an example of how natural
selection works.
Natural Selection is the process by which individuals that are better suited to their
environment survive and reproduce most successfully. In order for this process to
work there must be:
1. Genetic Variation within the environment
2. Over- production of offspring
3. Struggle for existence
4. Differential Survival and reproduction
Differential = differing or varying according to circumstances (how well adapted
an organism is)
Natural selection is also called “survival of the fittest”. What does that
mean? Give an example.
Survival of the fittest means that the best adapted organisms will survive and
reproduce = contributing genes to the next generation. It does not necessarily
mean the “biggest” or “strongest.” If an organism is not well adapted to their
environment, they will not survive and/or reproduce – thus they do not contribute
their poorly adapted genes to the next generation.
2.
3.
List the four main points of Darwin’s Theory of Evolution
NOTE: Change question to read: “What are the main points of Darwin’s Theory”
Answers could vary – some more thorough than others. Students could discuss the
components of natural selection as seen in the answer to #1. Regardless, they must
understand that Darwin’s theory of evolution explains DESCENT WITH
MODIFICATION BY NATURAL SELECTION.
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4.
Using natural selection as the basis for your answer, explain why giraffes
have long necks.
In the giraffe population there is genetic variation that determines neck length.
Some giraffes have longer necks than others.
There are more giraffes in the population than can be supported by the leaves on
trees in the environment.
Giraffes with longer necks will be better able to get food from the trees needed to
survive. Giraffes with short necks will not have food and will not survive.
The Giraffes with longer necks will survive to reproduce and pass on their “long
neck” trait to their offspring.
5.
Use the graph to answer the question below:
Tail length in mice varies within a population. Scientists observed change in the
distribution of tail lengths in a mouse population over time. At the genetic level,
what has most likely happened to the allele for the shortest tail lengths?
A. The allele changed from being dominant to being recessive.
B. The allele changed from being autosomal to being sex-linked.
C. The allele became less frequent than the alleles for longer tail lengths.
D. The allele began to code for long tail lengths instead of the shortest ones.
Answer: C
6.
What is an adaptation? How can it be inherited?
An adaptation is an inherited characterist that increases an organism’s chance of
survival. It is inherited through DNA passed from parent to offspring.
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7.
Finches on the Galapagos Islands have different beak sizes depending on
which island they are on. What is the reason for this adaptation?
Finches beak size varies based on food source (diet) available to them – insect
eater, cactus eater, seed eater, etc..
8.
Use the graph to answer the question below:
The graphs illustrate change in a lizard population over time. Which process most
likely led to the change in the lizard population?
A. natural selection acting on a harmful trait
B. natural selection acting on a beneficial trait
C. natural selection acting on a dominant trait
D. natural selection acting on a recessive trait
Answer: B
9.
Explain how the founder effect is an example of genetic drift?
The founder effect is a random change in the gene pool that occurs when a small
colony is separated / breaks off from a population. This occurs when the gene pool
of the colony is not a good representation of the gene pool of the original
population.
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10. If a species can’t adapt to an environmental change, what can happen to it?
If it doesn’t adapt, it will not survive.
11. The combined genetic information (alleles) of all the members of a particular
population make up the population’s ____gene pool___________________.
12. What is speciation?
Speciation is the formation of a new species.
13.
1.
2.
3.
4.
5.
6.
What are the basic steps of speciation, and how does this relate to the
Galapagos Islands and Darwin’s discoveries about the species found on each
island?
Founders arrive
Separation of populations
Changes in the gene pool
Reproductive isolation
Ecological Competition
Continued Evolution
14. What is genetic drift? Give an example.
Genetic drift is a random change in the allele frequencies that occurs in small
populations.
15.
If the vegetation on an island produces hard seeds, how might that affect the
evolution of a species of birds?
If hard seeds are the food source on an island the birds with beaks that are best
adapted to crack the hard seeds would be able to survive and reproduce. These
beaks would probably be larger/stronger crushing beaks. Those without the large
crushing beak would not survive (due to lack of food) and/or not reproduce (due to
lack of energy). In the next generation there would be a larger percentage of the
population with the large crushing beaks.
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16.
Speciation can happen if a group of individuals within a population becomes
isolated. What are the three kinds of isolation that can occur and give an
example of each?
Prezygotic Barriers:
Students could offer more than 3 isolating mechanisms: The could could be:
Behavioral Isolation – courtship rituals
Geographic/Habitat Isolation – living in separate regions
Temporal Isolation – mating at different times
Mechanical Isolation – reproductive parts don’t “fit”
Gametic Isolation – sperm of one species is unable to fertilize the egg of the other
Postzygotic barriers:
Hybrid Inviability – offspring are weak and may not surprise
Hybrid Sterility – offspring are sterile (donkeyXhorse = mule which is sterile)
Hybrid breakdown – 1st generation survives to reproduce but the following
generations become successively weaker and eventually may become sterile
Ultimately these isolating barriers could result in reproductive isolation.
17.
In North America, the eastern spotted skunk mates in late winter, and the
western spotted skunk mates in late summer. Even though their geographic
ranges overlap, the species do not mate with each other. What most likely
prevents these two species from interbreeding?
A. habitat isolation
B. gametic isolation
C. geographic isolation
D. reproductive isolation
Answer: D
If this were an open-ended, temporal isolation would be the best answer.
18. What is meant by natural (genetic) variation? What two things cause it?
Natural variation/genetic variation is shown in the diversity of traits seen in the
population. Variation that is inheritable provides the raw materials for natural
selection. Variation allows some organisms to be better adapted to their
environment allow them to survive to reproduce.
Cause of variation:
1. Mutations (helpful, harmful, and neutral) – major source of variation in
asexual reproducers/prokaryotes
2. Sexual reproduction – events of meiosis (crossing over, independent
assortment, & segregation of alleles) and random fertilization
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19.
A mutation occurs in a certain group of finches. The finches develop
narrower beaks in order to eat the insects that live in trees. What will
determine if the frequency of this new allele will increase in the finches?
If the mutation increases the fitness of the finch, then it will be better able to
survive and reproduced. This would ultimately lead an increase in the frequency
of the new allele in the gene pool.
If the mutation decreases the fitness, then it will not become more frequent in the
gene pool.
20.
Why are mutations in the ovaries and testes more likely to influence
evolution than mutations that occur in other parts of the body?
These cells contain the DNA that will be passed on to the next generation.
21.
A mutation occurs in the genes that code for coat color in deer. Which
change will most likely result from this mutation?
A.
a change in the selection pressures acting on coat color
B.
a change in the coat-color genes of deer predator species
C.
an increase in coat-color diversity in the population
D.
an increase in the number of genes for coat color in the population
Answer: C
22.
Charles Darwin took a journey around the world on the HMS Beagle.
Where did he go and how did this lead him to develop his theory of
evolution?
Darwin’s 5 year voyage took him around the world through the Atlantic Ocean
around the coast of South America through to the Galapagos Islands and around
the coast of Australia, through the Indian Ocean and around the southern tip of
Africa, back through the Atlantic Ocean to the British Isles.
On his voyage he saw a vast array of diverse organisms, he collected evidence
(specimens of living organisms & fossils remains), he made drawings of his
observations, he saw the impacts of geologic events (earthquakes and volcanoes)
and he read the work of Charles Lyell (a geologist who influenced Darwin
concerning the age of the earth). The Galapagos were a major influence – he was
fascinated by the unique creatures and how well adapted they were to island life.
This voyage helped him appreciate the vast diversity of organisms in the world.
The voyage made him question the divine creation of all organisms and the age of
the earth.
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13.
A vestigial organ is an organ that served a purpose in the distant ancestor of
an organism, but is not longer needed in the presently existing, recently
evolved, organism. Give an example of a human vestigial organ and explain
how it suggests common ancestry.
The appendix – this narrow, muscular tube attached to the large intestine served as
a special area to digest cellulose when the human diet consisted more of plant
matter than animals protein.
Wisdom teeth – early humans had to chew a lot of plants to get enough calories to
survive, making another row of molars helpful
Erector pili - are bundles of smooth muscle fibers that allow animals to puff up
their fur for insulation or to intimidate others. Humans retain this ability. They are
often called goose bumps.
24.
Modern whales resemble extinct land mammals in several characteristics.
What does this similarity suggest about the evolution of modern whales?
They evolved from a mammal that walked on land.
25. What are homologous structures? Give an example.
Homologous structures are structures that have different mature forms in different
organisms but develop from the same embryonic tissues.
The forelimb of birds, bats, whales, dogs, humans, horses, etc… have the same
number and type of bones.
26.
The frequency of an allele in a fly population changes from 89% to 20%
after three generations. Which other events most likely occurred during the
same time period?
A.
B.
C.
an environmental change and a fly population increase
an environmental change and a fly population decrease
interbreeding of flies with an invasive species and fly population
speciation
D.
interbreeding of flies with an established local species and fly
population speciation
Answer: B
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27.
Use the table below to answer the following question:
Students’ Observations of a Pond Ecosystem
Quantitative
Qualitative
37 fish and 3 frogs
Leaves lie on the bottom of the pond.
2 types of aquatic grass
Water insects move along the water’s
surface.
12 small rocks and 1 medium
All 3 frogs are sitting on a pond bank.
rock
sand
A group of students measured a ten-square-meter section of a pond
ecosystem and recorded observations. Which of the following statements is a
testable hypothesis?
A.
The frogs living in the pond represent a population.
B.
Water is an abiotic component in the pond ecosystem.
C.
If the fish are given more food, then they will be happier.
D.
If the frogs are startled, then they will jump into the water.
Answer: D
28. Use the diagram below to answer the following question:
Which organisms on the chart above share a common ancestor? How can
you tell?
Skunk and Otter – recent common branch point
Dog and Wolf – recent common branch point
Leopard with all - distant common branch point
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29.
Use the following diagram to answer the following question:
The skeletons of mammalian forelimbs represent variations of a structure
that was present in their common ancestor. What has most likely caused the
variation in forelimbs?
A.
changes in muscle structure
B.
changes in the genetic codes
C.
trait formation due to behaviors
D.
development of vestigial structures
Answer: B
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30.
Use the table below to answer the following questions:
Sequence Differences between COII Genes in Some Animals
Number of Base Differences from a Rat
Animal
Mouse
101
Cow
136
The gene COII is in the genome of many organisms. A comparison of the
number of base differences between the COII gene in a rat and that of two
other animals is shown.
Part A:
Based on the data, describe a possible evolutionary relationship
between rats, mice, and cows.
The rat and the mouse have fewer differences in their DNA which leads us to
believe that they have a closer common ancestor than the rat and the cow.
Part B:
Describe how different organisms having a common gene such
as COII supports the theory of evolution.
All three organisms have a common DNA sequence – homologous DNA sequence.
Homologous DNA sequences support the idea of having a common ancestor. The
amount of difference between homologous genes can be used as an indicator of
when genetic lines divereged / split from that common ancestor.
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