Chapter 16 Darwin’s Theory of Evolution
Name:
Biology
Date:
Period:
16.1 Darwin’s Voyage of Discovery
Term
Definition
The process by which modern organisms have changed over long periods of time
from their common ancestors
A preserved remain or trace of a once-living organism
Use the drawings of the tortoises to answer the following questions.
Isabela Island tortoise
Hood Island tortoise
1. The tortoises eat plants. On one island, plants grow very close to the ground. Which island is this most likely to
be? Circle the correct answer.
Isabela Island
Hood Island
2. Explain your answer to question 1. Why did you choose the island that you did?
3. Galápagos tortoises are certainly not the only organisms that show variations. Describe variations you have
observed among another group of organisms, like plants, butterflies, birds, or fish.
4. On the map, place the labels Rheas (S. America), Emus (Australia), and Ostriches (Africa) on the
continents where they are found. Why were the similarities among rheas, ostriches, and emus surprising to
Darwin?
5. Why might Darwin come to think that the finches of the Galápagos Islands might be related to the finches
of South America, despite how different the birds were in appearance?
6. Darwin observed that the birds he would eventually discover were finches had differently shaped beaks.
What might this suggest about the eating habits of the birds? Explain.
7. What did the similarities between fossil animals and modern animals suggest to Darwin?
8. Complete the graphic organizer by listing three ways that species vary. For each pattern of biodiversity,
list an example.
Species
vary
an example of which is
an example of which is
16.2 Ideas That Shaped Darwin’s Thinking
Lamarck’s Evolutionary Hypotheses
1. How did Lamarck propose that species change over time?
Use the diagram to answer the following questions.
2. According to Lamarck’s hypothesis, what occurs
between steps 2 and 3 in the diagram above to
make the crab’s claw grow larger?
3. Which step in the diagram shows the inheritance of acquired traits as proposed
by Lamarck?
an example of which is
4. How would Lamarck have explained the length of a giraffe’s neck?
Population Growth - For the following questions, write the letter of the correct answer on the line at the left.
______5.
Which observation caused Thomas Malthus to form his theory about population growth?
a. Human birth rate was higher than the death rate.
b. War caused the death of thousands of people.
c. Famines were common in England in the 1800s.
d. The offspring of most species survived into adulthood.
______6.
Which of the following is an idea attributed to Malthus?
a. As a population decreases in size, warfare and famine become more common.
b. As a population increases in size, the percentage of offspring that survive also increases.
c. If the human population grew unchecked, its rate of evolution would increase geometrically.
d. If the human population grew unchecked, there wouldn’t be enough living space and food for
everyone.
______7.
Malthus’s ideas led Darwin to conclude that
a. Earth is much older than previously thought.
b. the size of the human population can grow indefinitely.
c. many more organisms are born than will survive and reproduce.
d. organisms are able to evolve through a process known as artificial selection.
Artificial Selection
8. How do humans affect artificial selection? What role does nature play?
9. What is another name for artificial selection?
10. Describe how you could use artificial selection to breed pigeons with large beaks.
16.3 Darwin Presents His Case
Common Descent Darwin argued that all species are descended, with modification, from common ancestors.
Through descent with modification, all organisms—living and extinct— are linked on a single tree of life.
Term
Definition
An inherited characteristic that increases an organism’s ability to survive
How well an organism can survive and reproduce in an environment
The process by which organisms that are most suited to their environment
survive and reproduce
Evolution by Natural Selection
1. What does the phrase struggle for existence mean?
2. Why is camouflage considered an adaptation?
3. How does an animal’s level of fitness relate to its chances of survival and reproduction?
Evolution by Natural Selection - An adaptation is an inherited characteristic that helps an organism survive
and reproduce in its environment. Over time, adaptations become more and more common in the population.
For example, suppose that the water in a pond gets darker over a period of four years. The diagrams and table
below show what might happen to a frog population living in the pond. Use the diagrams below to complete the
table.
Year 1
Year 4
Year 2
Year 3
Adaptations of Frog Populations Over Time
Year
Light-Colored Frogs
1
6
Dark-Colored Frogs
2
3
4
4. In which year was the number of light-colored frogs greater than the number of dark-colored frogs?
5. How did the numbers of light- and dark-colored frogs change over time?
6. Which adaptation is best suited to life in the pond in Year 3? Circle one
light coloring
dark coloring
7. How do the dark-colored frogs show “survival of the fittest”?
8. How is natural selection different from artificial selection?
For the following questions, write True if the statement is true. If the statement is false, change the underlined
word or words to make the statement true.
9.
_______________ Natural selection acts on acquired traits.
10. _______________ Any inherited characteristic that increases an organism’s chance of survival is
considered an adaptation.
11. _______________ Natural selection is the ability of an individual to survive and reproduce in its specific
environment.
Below is a partially completed flowchart that models how natural selection drives evolution. The missing steps
are listed below, out of order. Write the missing step in a blank box in the flowchart.
 Adaptations are passed on to the next generation.
 The accumulation of adaptations may lead to the evolution of a new species.
 These offspring have few or no offspring of their own.
 Some offspring inherit traits that increase fitness (adaptations).
Individuals in a population have
many variations.
Some offspring inherit traits that
decrease fitness.
Over time, adaptations accumulate in a
population.
Common Descent -For the following questions, complete each statement by writing the correct word from the
word bank.
descended
evolve
modification
reproduce
different
fossil
related
stability
12. Natural selection depends on the ability of organisms to
, which means to leave
descendants.
13. Every organism alive today
from ancestors who survived and reproduced.
14. Over many generations, adaptation could cause successful species to
into new species.
15. Common descent suggests that all species, living and extinct, are
.
16. The principle that living species descend, with changes, from other species over time is referred to as
descent with
17. The
of time.
.
record provides physical evidence of descent with modification over long periods
16.4 Evidence of Evolution
The chart below shows key terms from the lesson with their definitions. Complete the chart by writing a
strategy to help you remember the meaning of each term. One has been done for you.
Term
Definition
Body parts that share the same function but not the same
structure
The study of where organisms now live and where their
ancestors lived in the past
Structures that are shared by organisms and that have been
inherited from a common ancestor
Homologous structures that have little or no useful function in
an organism
Concept Map A concept map can help you organize information and show how ideas are connected. Fill in the
concept map below using the bank below.
 Fossils
 Where organisms live now,
 How organisms have
 Genetics
where their ancestors lived
changed over time
 Tests of natural selection
 Embryology
 Homologous structures
is the study
of
Biogeography
show
Evidence of
Evolution
includes
Comparing
anatomy
Includes looking
at
like
and
The Grants’ Study of Galápagos finches
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The Age of Earth and Fossils
In the fossil record, an intermediate form is a fossil that shows some characteristics of an earlier related
organism and some characteristics of a later related organism. The diagrams below show organisms whose
fossils make up part of the fossil record. The organisms are in order from oldest (organism 1) to most
recent (organism 6). Use the diagrams to answer the questions.
1.
2.
Draw an animal that might have been an intermediate form between organism 1 and organism 3.
Draw an animal that might have been an intermediate form between organism 4 and organism 6.
Organism 1 (oldest)
Organism 2
Organism 3
Organism 4
Organism 5
Organism 6 (most recent)
3.
Describe one change you see between organism 1 and organism 3.
4.
Describe a situation in which organism 4 might have had an advantage over organism 3?
5.
How might these fossils provide evidence for evolution?
Complete the table about types of anatomical structures.
Types of Anatomical Structures
Structure Type
Description
Structures that are shared by related species
and that have been inherited from a common
ancestor
Example
Body parts that share common function, but
not structure
Body parts in animals that are so reduced
in size that they are just vestiges, or traces,
of homologous structures in other species
Match the structure with the correct type. A structure type may be used more than once.
Anatomical Structure
Structure Type
_____
_____
_____
_____
_____
6.
7.
8.
9.
10.
bat wing and mouse arm
reptile foot and bird foot
dolphin fin and fish tail
eyes on a blind cave fish
snake tongue and dog nose
A. homologous structure
B. analogous structure
C. vestigial structure
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Use the illustrated homologous structures to answer the following questions.
11. How are the forelimbs similar?
12. How are the forelimbs different?
13. How are homologous structures such as forelimbs evidence for common descent?
14. How does the pattern of embryological development provide further evidence that organisms have
descended from a common ancestor?
Comparing Anatomy and Embryology/Genetics and Molecular Biology
Darwin’s basic ideas about evolution have been supported by scientific evidence. The chart below lists some of
the evidence of evolution. Use the word bank and what you know about the evidence supporting evolution to
complete the chart.
biogeography
genetics
embryological
homologous structures
fossil record
development
Type of Evidence
What It Reveals
Different species have similar structures which have been
inherited from a common ancestor.
Animals with backbones have a common ancestor, as shown by
how these organisms develop before they are born.
Intermediate forms show that organisms have changed over time.
Species have adapted over time to local conditions.
Almost all organisms share a common genetic code.
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15. What is the difference between a homologous structure and an analogous structure?
Finch Beak Tools An analogy takes two things that seem to be different and shows how they can be similar.
16. How does comparing the finches’ beaks to tools help you understand how different beak shapes can help or
harm a finch?
Biogeography, Genetics and Molecular Biology – use the word bank below to fill in the answers.
ancestors
different
DNA
genetics
homologous
protein
17. Biogeographers study where organisms live now and where they and their
RNA
similar
structure
lived in the past.
18. When individuals from a mainland bird population immigrate to various islands, natural selection may result
in closely related, but
, island species.
19. Distantly related organisms may be similar if they live in
20. The science of
21. All living cells use
provides molecular evidence that supports evolutionary theory.
and
to code heritable information.
22. The universal genetic code is used by almost all organisms to direct
23. Proteins that are
environments.
synthesis.
share extensive structural and chemical similarities.
24. Relatively minor changes in an organism’s genome can produce major changes in an organism’s
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Chapter Vocabulary Review - Match the term with its definition.
Term
Definition
____ 25. evolution
A. Change over time
____ 26. fossil
B. Inherited characteristic that increases an organism’s chance of
survival
____ 27. fitness
C. Preserved remains of an ancient organism
____ 28. adaptation
D. The process by which organisms with variations most suited to
their environment survive and leave more offspring than others
____ 29. natural selection
E. The eyes of a blind cavefish.
____ 30. homologous structures
F. Structures that develop from the same embryonic tissues but
have different mature forms
____ 31. vestigial structures
G. Ability of an individual to survive and reproduce in a specific
environment
32. Does the illustration below show analogous or homologous structures? Explain.
33. Who developed the theory of evolution that includes natural section?
34. What is NOT part of Darwin’s Theory of Evolution?
a. Acquired characteristics
b. Common descent
c. Natural selection
d. Variations and adaptations
35. What would be a favorable trait for a rabbit trying to avoid predators in a snowy climate?
a. White fur
b. Brown fur
c. Long ears
d. Short ears
36. Which of the following statements is true?
a. All living cells have different genetic codes.
b. All living cells have a common genetic code.
c. All living organisms have different ancestors.
d. All living organisms have acquired traits that are passed on.
37. Both bats and mosquitos have wings. This is an example of a(n)
a. Analogous structure.
c. Vestigial structure.
b. Homologous structure.
d. None of the above.
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38. Darwin’s theory of evolution is supported by
a. DNA evidence.
b. Fossil evidence.
c. Embryology.
d. All of the above.
39. Use the Venn Diagrams to compare artificial Selection and natural Selection:
Artificial Selection
Natural Selection
40. Complete the concept map.
Evidence for
Evolution
includes
11
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