Name______________________________ Class __________________ Date ____________

15 Darwin’s Theory of Evolution

Section 16–1 Darwin’s Voyage of Discovery (pages 448–453)


Darwin’s Epic Journey


1.      During Darwin’s time, geologists were suggesting that Earth was         ____________.


2.      The process of change over time is ________________________________________.


3.       Darwin’s work offers insight into the living world by showing organisms are constantly____________________________________.


Observations Aboard the Beagle

4.      Darwin noticed that ecologically similar yet, ______________________________

inhabited ecologically similar yet, ______________________________________.


Use the drawings of the tortoises to answer Questions 5 and 6.


Isabela Island tortoise                                       Hood Island tortoise




5.      What important information about the Galápagos Islands tortoises did Darwin learn?



6.      Given its body structure, which tortoise above would require a habitat where food is easy to reach?



7.      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?



8.      What are fossils?




9.      What did the similarities between fossil animals and modern animals, like the glyptodont and armadillo, suggest to Darwin?







10.  Complete the graphic organizer by listing three ways that species vary. For each pattern of biodiversity, list an example that Darwin observed.


Section 16-2 Ideas that Shaped Darwin’s Thinking (pages 454–458)


An Ancient, Changing Earth

11.  Who were the two scientists who helped Darwin and others recognize how old the Earth is?



12.  In what two ways did an understanding of geology influence Darwin? K


Earth could change over time

For Questions 13-17, write True if the statement is true. If the statement is false, change the underlined word or words to make the statement true.

                                13. Hutton realized that Earth was much younger than previously believed.

                                14. Lyell thought most geological processes operated extremely quickly.

                                15. The processes that changed Earth in the past are different from the processes that operate in the present.

                                16. Lyell’s work explained how large geological features could be built up or torn down over long periods of time.

that there had been enough time for life to change.

Lamarck’s Evolution Hypotheses

17.  How did Lamarck propose that species change over time?



Use the diagram to answer Questions 18–19.




18.  According to Lamarck’s hypothesis, what occurs between steps 2 and 3 in the diagram above to make the crab’s claw grow larger?




19.  Which step in the diagram above shows the inheritance of acquired traits as proposed by Lamarck?



20.  Which of Lamarck’s ideas turned out to be true? Which turned out to be false?




Population Growth

              21. 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.

              22. 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.

              23. 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

24.  How do humans affect artificial selection? What role does nature play?



25.  What is another name for artificial selection?



Section 16–3 Darwin Presents His Case (pages 460–464)


Evolution by Natural Selection

26.  What does the phrase struggle for existence mean?



27.  Why is camouflage considered an adaptation?



28.  How does an animal’s level of fitness relate to its chances of survival and reproduction?



29.  Below is a partially completed flowchart that models how natural selection drives evolution. The missing steps are listed below, out of order, and lettered A–D. Write the letter of the missing step in a blank box in the flowchart.

A. Adaptations are passed on to the next generation.

B. The accumulation of adaptations may lead to the evolution of a new species.

C. These offspring have few or no offspring of their own.

D. Some offspring inherit traits that increase fitness (adaptations).





Common Descent

30.  Natural selection depends on the ability of organisms to                  ____________, which means to leave descendants.

31.  Every organism alive today                                                               from ancestors who survived and reproduced.

32.   Over many generations, adaptation could cause successful species to            ________________ into new species.

33.  Common descent suggests that all species, living and extinct, are ________________           .

34.   The principle that living species descend, with changes, from other species over time is referred to as                                                                                                          .

35.  The                                                                                                    provides physical evidence of descent with modification over long periods of time.


Section 16–4 Evidence of Evolution (pages 465-473)



36.  Biogeographers study where organisms live now and where they and their _______________          lived in the past.

37.   When individuals from a mainland bird population immigrate to various islands, natural selection may result in          , but different, island species.

38.  Distantly related organisms may be similar if they live in                                          .


39.  What explains the existence of similar but unrelated species?


The Age of Earth and Fossils

40.  The illustrations below show organisms whose fossils make up part of the fossil record. The organisms are in order from oldest to most recent. In the boxes, draw an animal that might have been an intermediate form

between the shown organisms.



Comparing Anatomy and Embryology

41.  How are homologous structures such as forelimbs evidence for common descent?



42.   How does the pattern of embryological development provide further evidence that organisms have descended from a common ancestor?



Match the anatomical structure with the correct type:

A. homologous structure           B. analogous structure            C. vestigial structure

Anatomical Structure

               43. bat wing and mouse arm               46. eyes on a blind cave fish

               44. reptile foot and bird foot                          47. snake tongue and dog nose

               45. dolphin fin and fish tail

Genetics and Molecular Biology

48.  The science of                       provides molecular evidence that supports evolutionary theory.

49.   All living cells use               ____ and ______________        to code heritable information.

50.  The universal genetic code is used by almost all organisms to             _______________________.

51.   Proteins that are                   _________ share extensive structural and chemical similarities.

52.   Cytochrome c is a protein used for     _____________________ in almost every living cell.

53.   Homologous genes called Hox genes control timing and growth in ______________           .

54.   Relatively minor changes in an organism’s genome can produce major changes in an organism’s     .

Testing Natural Selection

               56.  Which of the following hypotheses did the Grants test?

A. Differences in beak size and shape produce differences in fitness.

B. For beak size and shape to evolve, the birds must leave the islands.

C. For beak size and shape to evolve, the climate must change radically.

D. Differences in beak size and shape are not determined by genetic mutations.

              57.  The data that the Grants collected proved that there is

A. no link between the environment and the shape of finch feet.

B. no link between the environment and the shape of finch beaks.

C. great variation of heritable traits among Galápagos finches.

D. very little variation of heritable traits among Galápagos finches.

              58.  The Grants conducted their experiment to test which of the following processes?

A. Natural selection                   C. Artificial selection

B. Genetic mutation                  D. Sexual reproduction