Name___________________________ Class __________________ Date ______________

History of Life

Section 19-1 The Fossil Record (pages 538–545)


Fossils and Ancient Life

1.       Species that died out are said to be    _____________________________________.


2.       Most fossils are found in layers of    _________________________________ rock.



3.       Fill in the flowchart to explain how fossils are formed.





















4.       Scientists who study fossils are called _________________________________.



5.       What do we learn from the fossil record?




Dating Earth’s History

6.       What is an index fossil? What do index fossils reveal about other material found with them?




7.       Fossil A is found in a layer of rock above a layer containing Fossil B. Which fossil is probably older? Explain your answer.





8.       List the two techniques paleontologists use to determine the age of fossils.




9.      The length of time required for half of the radioactive atoms in a sample to decay is

called a(an) ___________________________________________________________.


10.  How do scientists calculate the age of a sample using radioactive dating?




11.   A species that is easily recognizable, existed for a relatively short period of time, and covered a wide geographic area may be used as a(n)

A. index fossil.                                   C. microfossil.

B. fossil record.                                  D. macrofossil.


12.   The same index fossil is found in rock layers A and B that are separated by several miles (Figure 19-3). What can you infer about the relationship between the rock layers?

A. Layer A is older than B.

B. The sediments in layer B were deposited before those in layer A.

C. Layers A and B are probably about the same age.

D. Layer B probably contains more radioactive isotopes than layer A.


Geologic Time Scale

13.  Fill in the missing eras and periods in the geologic time scale below.


Time (millions of years ago)































Precambrian Time

For Questions 14–15, refer to the Visual Analogy of life as a clock.

14.  _________Which of the following appeared on Earth most recently?

A. chordates

B. tetrapods

C. dinosaurs

D. land plants

15._______ Dinosaurs appeared before

A. mammals.

B. photosynthesis.

C. chordates.

D. land plants.


Life on a Changing Planet


16.  What processes have altered habitats of living organisms repeatedly throughout Earth history?



17.   The actions of __________________________________ over time have changed conditions in the land, water and atmosphere of the Earth.



Section 19–2 Patterns and Processes of Evolution (pages 546–552)


Speciation and Extinction

                               18.   Large-scale evolutionary changes that usually take place over long periods of time are referred to as speciation.

                               19.   Many species disappear rapidly during a background extinction.

                               20.   The rate of speciation in a clade must be equal to or greater than the rate of extinction in order for a clade to survive.

                               21.   Immediately after a mass extinction, biodiversity is dramatically reduced.


22.  What are possible causes of mass extinction?




23.  What effects have mass extinctions had on the history of life?



Rate of Evolution

24.  Horseshoe crabs have changed little in structure from the time they first showed up in the fossil record. Which pattern of evolution do horseshoe crabs likely follow—gradualism or punctuated equilibrium? Explain your answer.




25.  Label the diagram below that shows gradualism.

26.   Label the diagram below that shows punctuated equilibrium.






Adaptive Radiation and Convergent Evolution

                27. The process in which a single species or a small group of species evolves into diverse forms that live in different ways is called

A. coevolution.                                     C. adaptive radiation.

B. macroevolution.                                D. convergent evolution.

                28. The process by which unrelated organisms come to resemble one another is

A. coevolution.                                      C. adaptive radiation.

B. macroevolution.                                D. convergent evolution.

                29. What contributed to the adaptive radiation of mammals?

A. the evolution of plants                      C. the decrease in ocean depth

B. the extinction of most dinosaurs       D. continental drift

               30. Which of the following is an example of convergent evolution?

A. bird’s wing and fish’s fin                   C. shark’s fin and dolphin’s limb

B. human’s arm and bird’s wing             D. human’s leg and dolphin’s limb

31.  Adaptive radiation is the process by which

A. species evolve together.

B. unrelated species evolve to look alike.

C. one species evolves into many forms that live in different ways.

D. one species evolves into a single new species.



32.  What is coevolution?



33.  I’iwi birds have long, curved beaks that enable them to get nectar from tubular lobelia flowers. What might happen if the lobelia die out?


Section 19–3 Earth’s Early History (pages 553–563)

The Mysteries of Life’s Origins

34.  What important element was missing from Earth’s early atmosphere?



35.  What was the purpose of Miller and Urey’s experiment?



36.  What are protenoid microspheres?



37.  Why do scientists think that RNA may have evolved before DNA?



Origin of Eukaryotic Cells

38. Draw the step in the endosymbiotic theory that shows the origin of chloroplasts. Label the structures in your drawing. 

39.   What does the endosymbiotic theory propose?




40.  Name the three pieces of evidence that support the endosymbiotic theory.







Sexual Reproduction and Multicellularity

41.  How did sexual reproduction speed up the evolutionary process?



42.  What is the most likely cause of the great amount of diversity currently seen in multicellular life forms?