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Further Challenges
Figure 3.4 The
bacteriophage
(photographed at
240,000⫻) is a virus
that attacks bacteria.
Explain
Elaborate
Read these observations about a virus, called a bacteriophage (see Figure 3.4), that
infects bacteria.
A bacteriophage
◆ contains genetic material,
◆ reproduces only when inside another organism,
◆ has an outer case made of protein,
◆ injects genetic material into a bacterial cell, and
◆ uses the energy and the structure of the bacterial cell to make parts that
assemble into copies of itself (and often kills the bacterial cell).
You may have noticed that neither the DVD segment nor the essay contained any
reference to viruses. Yet, we often think about viruses in relation to life. For example,
have you ever heard someone complain about being attacked by a virus?
1. Use your knowledge of the unifying principles of life to construct a wellreasoned argument to answer the question, Is the bacteriophage alive?
2. For a moment, assume that scientists have decided that a virus should be
considered alive. Select one of the five kingdoms in which scientists would likely
categorize viruses. Support your answer with specific references to the unifying
principles and to the information about the bacteriophage listed above.
Adaptation, Diversity,
and Evolution
Think back to the organisms you saw in the previous activity, A Look at Diversity.
Each one shares the general characteristics of the kingdom in which it is categorized,
yet each is uniquely its own creature. Every living organism has peculiarities of
structure, function, and behavior that make it distinctly different from all of the others.
In Chapter 2, you learned about evolution—the process of change and selection
that can introduce and spread biological differences through a population of
organisms. Can that process explain all of the structural, functional, and behavioral
diversity that we find on earth?
Let’s examine the relationship between evolution and diversity more closely. We
will need to consider the more fundamental relationship between a species and the
environment in which it lives. Recall from Chapter 2 that inherited characteristics
that help an organism survive and reproduce within a particular environment are
called adaptations. What happens to organisms with adaptations that equip them to
live in a particular set of environmental conditions when that environment changes?
Is it possible that new characteristics that appear in a species through mutation
would allow organisms to live in new environments?
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Unit 1: Chapter 3 EXPLAIN/ELABORATE: Adaptation, Diversity, and Evolution
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To discover some answers to those questions, consider life in two very different
settings: first, across a series of oceanic life zones, and second, across a series of eras in
the earth’s history.
Materials
(per team of 4)
slides and coverslips
hand lens
dissecting needles with corks on tips
large sheet of paper
plant specimens
compound microscope
forceps
scalpel
4 felt-tipped markers
DVD and player
PROCESS AND PROCEDURES
Part A Diversity and Adaptation in a Marine Environment
1. Observe the DVD segment “Marine Life.”
a. Pay particular attention to the conditions that are present in each of the
different environments described. Indicate these conditions in a few words
at the appropriate places on Copymaster Oceanic Life Zones.
b. Work with the other members of your team to write on your copymaster
the names of several organisms that live in each life zone.
2. For each species, briefly describe 1 adaptation that appears to make it better
able to survive in the particular environment where it is usually found.
Adaptations may be structural, functional, behavioral, or a combination of these.
Examples of adaptations that you might use include lungs, gills, internal skeleton,
external skeleton, structural protections against predation, behavioral protections
against predation, and feeding habits.
The information on Copymaster Marine Organisms will help you complete this task.
N S TA
Topic: evolution
Go to: www.scilinks.org
Code: human3E71
3. Work with the other members of your team to answer the following questions.
Record your responses in your journal.
a. In general, do most of these marine organisms appear to be well-suited to
survival in their environments? Support your answer with specific examples.
b. Are all inherited characteristics adaptations? Explain your answer, and
support it with specific examples.
c. Name a characteristic that is an adaptation in 1 environment but would not
be an adaptation in another environment.
d. What explanation can you offer for the presence of characteristics that may
not be particularly adaptive for a modern organism in its current environment?
Part B Diversity and Adaptation across Time
1. Work with the members of your team to examine the plant specimens that
your teacher has provided.
EXPLAIN/ELABORATE: Adaptation, Diversity, and Evolution
Unit 1: Chapter 3
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Manipulate, dissect, or otherwise examine the specimens to gather as much
information as possible.
CAUTION: Scalpel blades and needles are sharp; handle with care. Replace cork on
needle tip after use.
2. Record your plant observations in your journal. Use your sketching skills to
record the observations that are best recorded through drawings.
3. Respond to the following items. Record your answers in your journal.
a. Identify at least 1 characteristic that all of these organisms share.
4.
PAGE 134
5.
6.
7.
b. Are these organisms as diverse as those in the DVD segment “Marine
Life,” or are they more similar to each other? Explain your answer.
Read the essay From Cell to Seed on page 134 for a short description of the
evolution of modern plants. In your journal, make a list of the major
adaptations that took place during the evolution of modern plants.
For each plant specimen that you observed, use your list of adaptations from
step 4 to help you identify at least 1 characteristic that biologists might use to
distinguish that plant from all of the others. Record these characteristics in
your journal.
Arrange your plant specimens in groups that represent those that are most
closely related. Discuss and identify at least 1 characteristic that each group
shares.
Study the branching diagram in Figure 3.5. This diagram shows the
relatedness of some vertebrates.
The points where branches separate represent where new lineages evolved from a
common ancestor.
8. What do scientists call the characteristics that enable organisms to function
better in their environment?
9. As a team, create a branching pattern on your large sheet of paper that
organizes your plant specimens. Think as a biologist would and classify
them according to their evolutionary divergence, or separation from an
ancestral form.
Be sure that someone who is not in your team would understand your diagram.
10. Label your diagram with the names of the plant specimens. Include a short
statement that identifies the major distinguishing characteristic that caused
you to place it at that point in the diagram.
11. Post your diagram in your classroom as your teacher directs. Be prepared to
share your ideas in a class discussion.
Analysis
Work with the members of your team to answer the following questions about
the relationships among adaptation, diversity, and evolution. Record your answers in
your journal.
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feathers
fur; mammary glands
claws or nails
lungs
Figure 3.5
A branching diagram shows the relatedness of organisms.
1. What are adaptations? Illustrate your answer using examples drawn from the
organisms that you studied in Part A and Part B.
2. How is the diversity of organisms on earth related to the diversity of
environments in which organisms live? Illustrate your answer using examples
drawn from the organisms that you studied in Part A and Part B.
3. If a mutation occurs in a population, it can result in the appearance of a new
adaptation. How might this relate to the ability of organisms to colonize new
environments? Illustrate your answer using examples drawn from your work in
Part B.
4. Explain biological diversity.
5. Propose a general explanation for the appearance of biological diversity on earth.
Refer to the essay Mutations Are a Source of Variation on page 139 for background
information that may help you answer this question.
Using Unity to Organize
Diversity
N S TA
Topic: origin of life
Go to: www.scilinks.org
Code: human3E73
PAGE 139
Elaborate
Living systems share different characteristics as a result of their common
ancestry. These characteristics provide biologists with a powerful set of guidelines for
organizing the millions of different types of life into large categories of similar
organisms. This organizing process, called classification, plays an important role in
biologists’ attempts to understand life. First, classification helps them subdivide the
numerous types of living (and extinct) organisms into groups of more or less similar
types that they can study productively. Second, the act of creating classification
categories helps them think about the evolutionary relationships that exist among
ELABORATE: Using Unity to Organize Diversity
Unit 1: Chapter 3
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