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CHAPTER 4 Life Changes Over Time
4-1
4-2
4-3
4-4
4-5
4-6
1
What is evolution?
Lesson Review
2
What are fossils?
Lesson Review
3
Kinds of Fossils
Enrichment Activity for Lesson 4-2
4
What evidence supports evolution?
Lesson Review
5
Radioactive Dating
Enrichment Activity for Lesson 4-3
6
What is natural selection?
Lesson Review
7
How does the environment affect natural selection?
Lesson Review
8
How have humans changed over time?
Lesson Review
9
THE BIG IDEA Integrating Earth Science: What is Geologic Time?
Lesson Review
10
Chapter 4 Key Term Review
11
Chapter 4 Test
12
Chapter 4 Answer Key
15
Concepts and Challenges in Life Science, Teacher’s Resources CD-ROM
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Life Changes Over Time: CHAPTER 4, page 1
Name
Class
Date
4-1 What is evolution?
Lesson Review
Write true if the statement is true. If the statement is false, change the underlined
term to make the statement true.
____________________ 1. Many scientists believe that new species develop from older species as a
result of adaptation.
____________________ 2. A change in a gene is called a mutation.
____________________ 3. A trait of an organism that helps it survive in its environment is called an
evolution.
____________________ 4. The process by which organisms change throughout time is called
evolution.
____________________ 5. A group of organisms that look alike and can reproduce among
themselves are a species.
____________________ 6. If a mutation is helpful to an organism, it may die out before passing the
trait on.
Skill Challenge
Skills: analyzing, relating concepts
Study the diagrams shown below. On the lines provided, explain what features
the cactus and the hawk have that allow it to survive in its environment.
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
Concepts and Challenges in Life Science, Teacher’s Resources CD-ROM
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Life Changes Over Time: CHAPTER 4, page 2
Name
Class
Date
4-2 What are fossils?
Lesson Review
Write the term that best completes each sentence in the space provided.
1. Species of organisms that are no longer found living are _______________________________________ .
2. The remains or traces of once-living organisms are ____________________________________________ .
3. Most fossils are found in layers of _______________________________________________________ rock.
4. An elephant-like animal called a __________________________________ has been found frozen in ice.
5. Insects are often preserved in hardened tree sap called _________________________________________ .
6. When an organism is buried in rock, it decays and leaves a cavity called a _______________________ .
7. When a mold fills with sand or mud and then hardens, a _____________________________ is formed.
8. Sediments are slowly changed to rock as __________________________ forces the sediments together.
Skill Challenge
Skills: identifying, relating concepts
Answer the questions about the drawings shown.
Figure 1
Figure 2
1. What organism is shown in Figure 1? _________________________________________________________
2. In what way is the organism in Figure 1 most likely to be preserved? _____________________________
3. Is the organism in Figure 1 an example of a living or an extinct species? __________________________
4. What organism is shown in Figure 2? _________________________________________________________
5. How is the organism in Figure 2 most likely to be preserved? ____________________________________
6. Is the organism in Figure 2 an example of a living species or an extinct species? ___________________
Concepts and Challenges in Life Science, Teacher’s Resources CD-ROM
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Life Changes Over Time: CHAPTER 4, page 3
Name
Class
Date
Kinds of Fossils
Enrichment Activity for Lesson 4-2
Skills: comparing, relating
PART A Read the passage. Then, answer the questions that follow.
Molds and Casts
Fossils often form when silt or mud covers an organism or part of an organism.
The silt or mud hardens before the organism decays. As the organism decays, a fossil
remains. A fossil mold is formed if a cavity is left in rock that has the shape of the
organism. A fossil cast forms if sediment fills the mold and then hardens.
1. What is a fossil mold? _______________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
2. What is a fossil cast? ________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
3. Is it possible for a fossil cast to form without a fossil mold? Why or why not? _____________________
___________________________________________________________________________________________
___________________________________________________________________________________________
PART B Identify the fossils below as either a fossil mold or a fossil cast.
1.
_______________________________________
2.
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______________________________________
Life Changes Over Time: CHAPTER 4, page 4
Name
Class
Date
4-3 What evidence supports evolution?
Lesson Review
Complete the following.
1. What does fossil evidence show about Earth’s climate? _________________________________________
2. For what animal is the most complete fossil record available? ____________________________________
3. Describe how the horse has evolved. __________________________________________________________
___________________________________________________________________________________________
4. What are homologous structures? ____________________________________________________________
___________________________________________________________________________________________
5. Name three homologous structures. __________________________________________________________
___________________________________________________________________________________________
6. What are vestigial structures? ________________________________________________________________
___________________________________________________________________________________________
7. How do scientists know that dogs and bears are closely related? _________________________________
Skill Challenge
Skills: sequencing, generalizing
Place the diagrams of horse evolution below in the correct order by writing the
letter A (earliest horse) through D (most recent horse) in the spaces provided.
Then, answer the question.
______ 1.
______ 2.
______ 3.
______ 4.
5. What generalization can you make about how horses have changed through time? ________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
Concepts and Challenges in Life Science, Teacher’s Resources CD-ROM
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Life Changes Over Time: CHAPTER 4, page 5
Name
Class
Date
Radioactive Dating
Enrichment Activity for Lesson 4-3
Skills: relating, calculating
PART A Read the passage. Then, answer the questions that follow.
Radioactive Dating
In the 1940s, scientists discovered that radioactive elements can be used to find
out how long ago a fossil organism lived. This method is called radioactive dating.
The actual age of a fossil can be identified using it. Radioactive elements give off
particles and energy as they decay. They decay at a fixed rate that can be measured.
Scientists measure the rate of radioactive decay in a unit called a half-life. A half-life is
the amount of time needed for one-half of the radioactive element to decay. By
measuring the amount of a particular radioactive element in a fossil, the number of
half-lives of the element is found. This is used to calculate the actual age of the fossil.
1. What is radioactive dating? __________________________________________________________________
___________________________________________________________________________________________
2. What is a half-life? __________________________________________________________________________
___________________________________________________________________________________________
PART B The table below lists the half-lives of certain radioactive elements. Use
the table to answer the questions that follow.
HALF-LIVES
Radioactive Element
Half-life
Rubidium–87
50 billion years
Uranium–238
4.5 billion years
Potassium–40
1.3 billion years
Carbon–14
5,770 years
1. What is the half-life of uranium–238? _________________________________________________________
2. Suppose a fossil contained one-half as much carbon–14 as when the organism first formed.
How old is the fossil? _______________________________________________________________________
3. Suppose a rock contained one-fourth as much potassium–40 as when it first formed. How old is
the rock? __________________________________________________________________________________
4. If 10 g of uranium–238 are present now, how much will be left in 4.5 billion years? How much
in 9 billion years? ___________________________________________________________________________
5. If 40 g of rubidium–87 are present now, how much will be left in 100 billion years? ________________
Concepts and Challenges in Life Science, Teacher’s Resources CD-ROM
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Life Changes Over Time: CHAPTER 4, page 6
Name
Class
Date
4-4 What is natural selection?
Lesson Review
PART A Answer the following questions.
1. Who was Jean Baptiste de Lamark? ___________________________________________________________
___________________________________________________________________________________________
2. What was Jean Baptiste de Lamark’s theory about evolution? ____________________________________
___________________________________________________________________________________________
PART B The main ideas of Darwin’s theory of natural selection are listed below.
Explain what is meant by each of these ideas.
1. Overproduction: ___________________________________________________________________________
___________________________________________________________________________________________
2. Struggle for Existence: ______________________________________________________________________
___________________________________________________________________________________________
3. Variation: _________________________________________________________________________________
___________________________________________________________________________________________
4. Survival of the Fittest: ______________________________________________________________________
___________________________________________________________________________________________
5. Evolution of New Species: __________________________________________________________________
___________________________________________________________________________________________
Skill Challenge
Skills: applying concepts, analyzing
Study the diagrams below. Identify how the diagrams relate to Darwin’s ideas
about natural selection.
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
Concepts and Challenges in Life Science, Teacher’s Resources CD-ROM
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Life Changes Over Time: CHAPTER 4, page 7
Name
Class
Date
4-5 How does the environment affect natural selection?
Lesson Review
Write true if the statement is true. If the statement is false, change the underlined
term to make the statement true.
____________________ 1. All organisms must have a living space that provides food, water, and shelter.
____________________ 2. Tigers that are slower and weaker are more likely to catch deer and survive.
____________________ 3. Human activities cannot produce great changes in the living spaces of other
organisms.
____________________ 4. Extinction is an example of how harmful materials from factories and cars
pollute the air, water, and land.
____________________ 5. After laws were passed in England to reduce air pollution, the number of
gray peppered moths rose.
____________________ 6. Extinction is the disappearance of all members of a species.
____________________ 7. The giant panda and the grizzly bear are both examples of extinct species.
Skill Challenge
Skills: identifying, relating concepts
Answer the questions about the drawings shown below.
Gray moth
Black moth
1. Which of these moths would be more likely to survive before the Industrial Revolution? ____________
____________________________________________________________________________________________
2. Which of these moths would be more likely to survive during the Industrial Revolution? ___________
____________________________________________________________________________________________
3. Which of these moths would be more likely to survive after the 1970s? ____________________________
____________________________________________________________________________________________
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Life Changes Over Time: CHAPTER 4
Name
Class
Date
4-6 How have humans changed over time?
Lesson Review
Answer the following.
1. What does Homo sapien mean? _______________________________________________________________
2. What is anthropology? ______________________________________________________________________
___________________________________________________________________________________________
3. About how old is the humanlike skeleton that Donald Johanson found and named Lucy?
___________________________________________________________________________________________
4. About how tall was Lucy? ___________________________________________________________________
5. List two ways that humans have changed through time. ________________________________________
___________________________________________________________________________________________
6. Name two types of early humans. ____________________________________________________________
7. In what ways were Cro-Magnons more like homo sapiens than the Neanderthals? ___________________
___________________________________________________________________________________________
___________________________________________________________________________________________
8. What kind of fossil evidence led scientists to say that later humanlike species lived
in caves, used fire, and made tools? ___________________________________________________________
___________________________________________________________________________________________
Skill Challenge
Skills: analyzing, applying concepts, sequencing
Study the human skulls shown below. Then, use what you learned about how
humans have changed through time to place the skulls in order from earliest (A)
to most recent (C). Write the correct letter in the space provided.
_____ 1.
_____ 2.
_____ 3.
4. Explain why you placed the skulls in the sequence you did. _____________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
Concepts and Challenges in Life Science, Teacher’s Resources CD-ROM
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Life Changes Over Time: CHAPTER 4, page 9
Name
THE
Class
Big IDEA
Chapter 4
Date
Integrating Earth Science
What is geologic time?
Lesson Review
Match each term in Column B with its description in Column A. Write the correct
letter in the space provided.
Column B
Column A
__________ 1. record of Earth’s history based upon the types of
organisms that lived at different times
__________ 2. large division of geologic time
__________ 3. age of something compared to the age of something else
__________ 4. periods are divided into these
__________ 5. kind of rock in which fossils form
a. era
b. relative age
c.
epochs
d. periods
e. sedimentary
f.
geologic time scale
__________ 6. eras are divided into these
Skill Challenge
Skills: analyzing, inferring, synthesizing
Complete the following.
1. What does the clock on page 113 of your text tell you about geologic time? ________________________
___________________________________________________________________________________________
2. Why do you think coal is called a fossil fuel? __________________________________________________
___________________________________________________________________________________________
3. If you were a geologist far in the future, what ancient artifacts might you find from our time
period? What might these objects tell you about life today? ______________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
Science Log Writing Activity
Complete the Science Log on a separate sheet of paper. To complete the Big Idea Online, go to
www.conceptsandchallenges.com. Follow the online instructions.
Concepts and Challenges in Life Science, Teacher’s Resources CD-ROM
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Life Changes Over Time: CHAPTER 4, page 10
Name
Class
Date
Chapter 4 Key Term Review
Use the clues to complete the crossword puzzle.
Clues
Across
Down
2. science that deals with the study of human
1. body parts that have the same basic structure
beings
3. hardened tree sap
4. differences in traits among individuals of a
species
7. body structure that seems to have no function
2. trait that helps an organism survive in its
environment
5. survival of offspring that have favorable traits
(two words)
6. a sudden change in a gene
8. remains or trace of a once-living organism
9. process by which organisms change over time
Concepts and Challenges in Life Science, Teacher’s Resources CD-ROM
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Life Changes Over Time: CHAPTER 4, page 11
Name
Class
Date
Chapter 4 Test
Interpreting Diagrams Use the diagram below to answer the questions that
follow. Write your answers in the spaces provided.
1. Which of the Homo sapiens lived from 130,000 to 35,000 years ago? _______________________________
2. How long ago did Homo habilis live on Earth? __________________________________________________
3. About how long did Homo erectus inhabit Earth? _______________________________________________
___________________________________________________________________________________________
4. How much longer than Homo habilis did Homo erectus inhabit Earth? _____________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
5. Which of the ancestors of modern humans inhabited Earth for the longest time? ___________________
___________________________________________________________________________________________
Multiple Choice Write the letter of the term or phrase that best completes the
statement or answers the question.
__________ 1. The process by which organisms change over time is known as
a. adaptation. b. evolution c. natural selection. d. variation.
__________ 2. The most complete fossil record of evolutionary change is that of
a. humans. b. the dinosaur. c. the horse. d. insects.
__________ 3. Differences among individuals in a species are called
a. adaptations. b. mutations. c. natural selection.
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d. variations.
Life Changes Over Time: CHAPTER 4, page 14
Name
Class
Date
Chapter 4 Test (continued)
__________ 4. An example of how human activities affect other organisms is
a. mutations. b. pollution. c. adaptations. d. a hominid.
__________ 5. Most fossils are formed in
a. igneous rock. b. sedimentary rock.
c. metamorphic rock.
d. clastic rock.
__________ 6. The science that deals with the study of human beings is known as
a. psychology. b. geology. c. biology. d. anthropology.
__________ 7. A sudden change in a gene is called
a. an adaptation. b. a mutation. c. a variation.
d. natural selection.
__________ 8. Any remain or trace of a once-living organism is a
a. skeleton. b. shell. c. fossil. d. sediment.
__________ 9. A group of organisms that look alike and can reproduce among themselves is known as
a. a species. b. ancestors. c. mutations. d. genes.
__________ 10. Body structures that seem to have no function are called
a. homologous structures. b. glands. c. vestigial structures.
d. mutations.
__________ 11. Special traits that help organisms survive in their environment are
a. adaptations. b. genes. c. mutations. d. fossils.
__________ 12. Body parts that are similar in structure are called
a. homologous structures.
b. vestigial structures.
c. the fossil record.
d. DNA evidence.
__________ 13. Organisms that are no longer found as living species are said to be
a. untraceable. b. rare. c. extinct. d. endangered.
__________ 14. The modern theory of evolution is called the theory of
a. relativity. b. natural selection. c. variation. d. adaptation.
__________ 15. Which of the following would most likely be found as a fossil?
a. a shell b. a body organ c. skin d. a leaf
__________ 16. The idea that each species produces more offspring than can survive is called
a. variation. b. natural selection c. evolution. d. overproduction.
__________ 17. Natural selection also is known as survival of the
a. species. b. variation. c. fittest. d. fossil.
__________ 18. All modern humans belong to the species
a. Cro-Magnon. b. Homo sapiens. c. Neanderthalensis.
d. humanoids.
__________ 19. About how many years old is the humanlike fossil called Lucy?
a. 1.5 billion years b. 5.3 million years c. 2.3 billion years d. 3.5 million years
__________ 20. Insect fossils often are found preserved in
a. amber. b. ice. c. tar. d. wood.
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Life Changes Over Time: CHAPTER 4, page 13
Name
Class
Date
Chapter 4 Test (continued)
Written Response Answer the following questions in complete sentences.
21. INFER: What might be the reason for the changes in skull shapes of human ancestors?
___________________________________________________________________________________________
___________________________________________________________________________________________
22. APPLY: Would species have evolved over time if the environments they lived in never changed?
Explain your answer. ________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
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Life Changes Over Time: CHAPTER 4, page 16
Answer Key
CHAPTER 4: LIFE CHANGES OVER TIME
4-1 What is evolution?
Lesson Review
1. evolution 2. true 3. an adaptation 4. true
5. true 6. harmful
Skill Challenge
The spines help the cactus retain water by fending
off animals that would eat the plant for its water.
The ridges help the cactus retain water by creating
shade from the sun on much of the cactus’s
surface. The hawk was a hooked beak and sharp
claws for catching and killing prey and sharp
eyesight to see prey while flying high above.
4-3 What evidence supports evolution?
(continued)
Skill Challenge
1. B 2. D 3. C 4. A 5. Each species has grown
larger.
4-3 What evidence supports evolution?
Enrichment Activity: Radioactive Dating
PART A
1. determining the actual age of a fossil by
measuring the amount of a radioactive element
remaining in the fossil 2. amount of time needed
for one-half of a radioactive element to break
down
4-2 What are fossils?
PART B
Lesson Review
1. extinct 2. fossils 3. sedimentary 4. mammoth
5. amber 6. mold 7. cast 8. great pressure
1. 4.5 billion years 2. 5,770 years 3. 2.6 billion
years 4. 5 g; 2.5 g 5. 10 g
Skill Challenge
1. mammoth 2. in ice 3. an extinct species
4. Possible answers: insect or fly 5. in amber 6. a
living species
4-2 What are fossils?
Enrichment Activity: Kinds of Fossils
PART A
1. cavity in a rock that has the shape of a buried
organism 2. copy of a fossil made from sediment
that hardened inside a fossil mold 3. no, because
the sediments that harden into a cast must be
shaped by a mold
PART B
1. fossil cast 2. fossil mold
4-3 What evidence supports evolution?
Lesson Review
1. Earth’s climate has changed many times
throughout Earth’s history. 2. the horse 3. The
horse evolved from a species called Eohippus,
which had toed feet, to Mesohippus, which was
larger, to Merychippus, which was larger still with
split hooves, to Equus, the modern horse. The
horse’s tooth and skull size have increased over
time as well. 4. body parts that have a similar
structure 5. lion’s foreleg, bat’s wing, and
dolphin’s flipper 6. body structures that seem to
have no function 7. They have very similar DNA.
4-4 What is natural selection?
Lesson Review
PART A
1. Jean Baptise de Lamark was one of the first
scientists to develop a theory of evolution.
2. Lamark hypothesized that all organisms
developed new characteristics to help them adapt
to their surroundings. Then, they passed on those
adapted traits to their offspring.
PART B
1. Each species produces more offspring than can
survive. Not all can survive because there is not
enough food or living space for all. 2. The
offspring of each generation compete for things
that they need to survive. Only a few will live long
enough to reproduce. The others will die. 3. The
offspring of each generation are not exactly alike.
For example, some organisms are faster or
stronger than others. 4. Some variations make
organisms better suited for survival in their
environments. These organisms are more likely to
survive and reproduce than are others.
5. Individuals with favorable variations survive and
reproduce. They pass their favorable traits to their
offspring. Therefore, their offspring are more likely
to survive and reproduce in the next generation.
Skill Challenge
The pictures show an overproduction of mice,
which causes a struggle for existence. A variation
occurs, making some mice larger than others.
These mice win battles for food, causing the
smaller mice to die out. The new larger mice make
a new species.
Concepts and Challenges in Life Science, Teacher’s Resources CD-ROM
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Life Changes Over Time: CHAPTER 4, page 17
Answer Key
4-5 How does the environment affect
natural selection?
Lesson Review
1. true 2. stronger and faster 3. can 4. Pollution
5. true 6. true 7. endangered
Skill Challenge
1. gray moth 2. black moth 3. gray moth
4-6
How have humans changed over
time?
Lesson Review
1. wise human 2. science that deals with the study
of humans 3. about 3.5 million years 4. about 1
meter 5. They have gotten larger; the size of their
skulls has increased. 6. Neanderthals and CroMagnons 7. Unlike Neanderthals, Cro-Magnons
lived together in large groups and were skilled
hunters and toolmakers. Cro-Magnons had a more
highly developed society in which people had more
specialized jobs, such as hunters and toolmakers.
8. Scientists found drawings on the walls of caves
and fossils of simple tools and burnt wood.
Skill Challenge
1. A 2. B 3. C 4. Possible answer: Skull A is the
smallest of the three, indicating that it is the oldest.
Skull B is larger than A and has a larger brain case.
Skull C is the largest of the three, indicating that it is
the most recent.
The Big Idea
CHAPTER 4: LIFE CHANGES OVER TIME
Key Term Review
Across
2. anthropology 3. amber 4. variation 7. vestigial
8. fossil 9. evolution
Down
1. homologous 2. adaptation 5. natural selection
6. mutation
CHAPTER 4: LIFE CHANGES OVER TIME
Chapter Test
Interpreting Diagrams
1. Homo sapiens neanderthalensis 2. A little more than
2 million years ago 3. A little more than 1 million
years 4. 0.5 million years 5. Australopithecus
afarensis
Multiple Choice
1. b 2. c 3. d 4. b 5. b 6. d 7. b 8. c 9. a 10. c
11. a 12. a 13. c 14. b 15. a 16. d 17. c 18. b
19. d 20. a
Written Response
21. As humanlike species evolved over time, their
skulls became larger as the size of their brain
increased. Each species was increasingly more
intelligent and humanlike than the humanlike
species of earlier ages.
22. It is not as likely that species would have evolved
over time without changes in the environment,
because evolution is the adaptation of a species to its
changed environment.
Lesson Review
1. f 2. a 3. b 4. c 5. e 6. d
Skill Challenge
1. The Precambrian Era has been the longest era so
far. The current era, the Cenozoic Era, has not lasted
very long in comparison. 2. Coal is made from the
fossilized remains of ancient plants. 3. Possible
answers: Artifacts may include remains of cell
phones, eyeglasses, snowboards, roller blades, and
computers. These objects would indicate that
humans were able to make many complex products
themselves.
Concepts and Challenges in Life Science, Teacher’s Resources CD-ROM
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Life Changes Over Time: CHAPTER 4, page 16