Biology Station 7(A)
Evidence of Change
Correlations to Texas Essential Knowledge and Skills:
Biology
(7) Science concepts. The student knows the theory of
biological evolution. The student is expected to:
(A) identify evidence of change in species using fossils, DNA
sequences, anatomical similarities, physiological
similarities, and embryology; and
(2) Scientific processes. The student uses scientific methods
during field and laboratory investigations. The student is
expected to:
(C) organize, analyze, evaluate, make inferences, and predict
trends from data; and
(D) communicate valid conclusions.
Purpose: The
purpose of this
station is to review
and reinforce
students’
understanding of the
evidence of change in
species using
anatomical
similarities.
Note: Text with a line
through it indicates this
part of the TEKS is not
being addressed in this
activity. Some TEKS
statements printed here
end with a; or and and
nothing thereafter—this
indicates that further
TEKS statements follow
but are not included
here.
Teacher Notes About the TEKS
In middle school, students learn that a species’ traits can change over several generations as a
result of natural selection and selective breeding. Students investigate how particular traits
may enhance species survival and reproduction and how different environments support
different varieties of organisms. In the last year of middle school, students come to recognize
that changes in environmental conditions can also affect the survival of species.
Students are expected to apply these middle school concepts to study biological evolution,
including its formal definition, in Biology.
Background Information for the Teacher
Biological evolution can be measured as the change in frequency of alleles within a gene
pool over a succession of generations. These changes, due primarily to mutations, gene
shuffling that takes place during sexual reproduction, or chromosome synapsis and crossover
during the early phases of sex cell production, can be exhibited as physical or biochemical.
Evidence for the changes in allele frequency can be found through analysis of DNA sequences
and examination of anatomical similarities, physiological similarities, and fossil records.
The most reliable methods for determining evolutionary relationships are the analyses of
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Essential Science Concepts for Exit-Level TAKS
Biology Station 7(A)
Evidence of Change
physiological similarities and DNA sequences. The more similar the DNA sequences are, the
more likely it is that the organisms share similar physiology. The fossil record, however
incomplete, may also provide important information about the evolutionary history of an
organism. Although anatomical similarities can serve as important evolutionary indicators, it
is important to recall that some similarities are the result of common environmental factors
rather than biological evolution. Analogous structures are anatomical similarities in
different species that are the result of adaptations to environmental factors. Homologous
structures are those anatomical similarities seen in different species that are a result of
common ancestry.
A cladogram is a commonly used method for phylogenetic analysis. The basic idea of a
cladogram is to group members that share a common evolutionary history. Each subsequent
species on a branch of a cladogram possesses a mixture of primitive characteristics that
existed in the common ancestor along with newly evolved characteristics.
Resources
Lenski, Richard E. “Evolution: Fact and Theory.” ActionBioscience.org.
www.actionbioscience.org/evolution/lenski.html. (Date retrieved: August 24, 2007.)
Copyright 2000–2007, American Institute of Biological Sciences.
Vavala, Phil. “Evolution Simulation.” Access Excellence at the National Health Museum.
www.accessexcellence.org/AE/SH/NSTA_NOR/vavala_evol.html. (Date retrieved: August
24, 2007.) Copyright @ Access Excellence @ The National Health Museum.
“Whale Evolution.” Evolution Library. WGBH Educational Foundation,
www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html. (Date retrieved: August 24,
2007.) Copyright 2001, WGBH Educational Foundation and Clear Blue Sky Productions, Inc.
Materials
Except for the question card, all materials are included in the blackline masters for this
station.
Whale skeleton cards
DNA sequence cards
DNA sequence cladogram
Horse evolution station mat
Horse evolution cards
Station information sheet
Student pages, including a glossary
Question card (see Advance Preparation)
Advance Preparation
1. Copy, cut, and laminate the whale skeleton cards, horse evolution cards, and DNA
sequence cards included in the blackline masters.
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Biology Station 7(A)
Evidence of Change
2. For each student, copy the DNA sequence cladogram, horse evolution station mat,
student pages, and station information sheet; for the station table, make a copy of the
DNA sequence cladogram, horse evolution station mat, and station information sheet.
3. Make a question card using question 52 from the Released TAKS Test for Exit Level
Science, July 2004. This released test can be found at www.tea.state.tx.us/
student.assessment/resources/release/taks.
Station Setup
1. Place the pictures of the whale skeletons, DNA sequence cards and cladogram, and horse
evolution cards and station mat at the station table.
2. Tape a copy of the station information sheet to the table. Students will use this to confirm
the station is set up correctly.
Procedures
1. When students arrive at the station, they should check the station setup against the
station information sheet at the table. If anything is missing or out of place, the students
should notify the teacher.
2. Students should read the procedures in the student pages and answer the questions.
Guide to Student Responses
Focus Question: What information can be gained by examining fossil remains of the
ancestors of modern organisms?
Scientists can determine how closely related fossil organisms are to modern species by
studying fossil remains. They can also predict what the environmental conditions were like
where the fossil organisms lived.
Questions
1. Sequence the whale skeleton cards in order from the oldest fossil to the most recent
skeleton. Justify your answer.
Rodhocetus balochistanensis, Ambulocetus natans, Orcinus orca
The fossils progress from a walking whale with front and hind legs (Rodhocetus
balochistanensis), to a whale with shorter front legs and outstretched hind legs
(Ambulocetus natans), to the most recent skeleton of a modern whale with flippers and
no hind legs (Orcinus orca).
2. What do the fossil remains of earlier whales indicate about changes in the whale’s habitat
over time?
The fossil remains show whales with legs, feet, and a pelvis. These are all indicators that
these organisms walked on land.
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Essential Science Concepts for Exit-Level TAKS
Biology Station 7(A)
Evidence of Change
3. If two different species have homologous structures, what can you tell about their
evolutionary history?
If two different species have homologous structures, they must share a common
ancestor.
4. Locate the DNA sequence cards at the station.
•
Place the shark, camel, and dolphin sequence cards in the appropriate spaces on the
cladogram.
•
Examine the DNA sequences on the remaining cards and compare them to the shark,
dolphin, and camel cards. Determine the correct position of each of the remaining
cards and place them on the cladogram. (The more closely the DNA sequences match,
the more closely related the organisms are to each other.)
•
Record the order of the sequence cards on your copy of the cladogram.
5. Examine the DNA sequence cladogram and determine which organisms are most closely
related based on their homologous structures. Justify your answer.
The shark and perch—streamlined body shape and fins (dorsal, lateral, and caudal).
The whale and dolphin—streamlined body shape and fins (dorsal, lateral, and caudal).
The similar body shapes and structures are the result a common ancestor shared by
each pair.
6. Sometimes organisms that do not have a common ancestor may have anatomical
similarities. These are called analogous structures. Examine the cladogram and
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Essential Science Concepts for Exit-Level TAKS
Biology Station 7(A)
Evidence of Change
determine which organism(s) share analogous structures with the perch and shark.
Describe the analogous structure(s) and explain why these similarities could exist in
organisms that do not share a common ancestor.
The whale and dolphin share analogous structures with the perch and shark. They have
similar fins and streamlined bodies because all of them live in water and swim.
7. Examine the cards that represent the evolution of the modern horse. Arrange the cards on
the horse evolution station mat to show changes that have occurred in the anatomy of the
horse from its most ancient ancestor to modern horses. Explain why you arranged the
cards in the order you selected.
8. Examine your completed chart that now shows evolutionary changes that have occurred
in the horse’s anatomy over time. Describe the major changes that you observe.
All parts of the horse’s anatomy have become larger, the face is longer, and the cheek
teeth have changed in number and size. The lower leg and feet have changed; the
number of toes has been reduced from four smaller toes to one large toe that we now
call the hoof.
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Essential Science Concepts for Exit-Level TAKS
Biology Station 7(A)
Evidence of Change
Blackline Masters
for
Biology Station 7(A)
Evidence of Change
Contents:
Station information sheet (1 copy for station table and 1 for each student)
Whale skeleton cards (1 set for station table)
DNA sequence cards (1 set for station table)
DNA sequence cladogram (1 copy for station table and 1 for each student)
Horse evolution station mat (1 copy for station table and 1 for each student)
Horse evolution cards (1 set for station table)
Student pages (1 copy for each student)
Glossary (1 copy for each student)
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Essential Science Concepts for Exit-Level TAKS
Biology Station 7(A)
Evidence of Change
Station Information Sheet
Biology Station 7(A)
Evidence of Change
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Essential Science Concepts for Exit-Level TAKS
Biology Station 7(A)
Evidence of Change
Whale Skeletons
Rodhocetus balochistanensis (Balochistan walking whale)
Ambulocetus natans (Walking whale)
Orcinus orca (Killer whale)
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Essential Science Concepts for Exit-Level TAKS
Charles A. Dana Center at The University of Texas at Austin
Biology Station 7(A)
Evidence of Change
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Essential Science Concepts for Exit-Level TAKS
Charles A. Dana Center at The University of Texas at Austin
Biology Station 7(A)
Evidence of Change
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Pliocene
Pleistocene
Biology Station 7(A)
Evidence of Change
Oligocene
Early Eocene
L ate Miocene
Pliohippus
Merychippus
Mesohippus
Hyracotherium
Horse Evolution Station Mat
Equus
Essential Science Concepts for Exit-Level TAKS
Charles A. Dana Center at The University of Texas at Austin
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Essential Science Concepts for Exit-Level TAKS
Charles A. Dana Center at The University of Texas at Austin
Biology Station 7(A)
Evidence of Change
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Biology Station 7(A)
Evidence of Change
Student Pages
Before You Begin
Check to see that all the items are present and organized according to the station
information sheet. If you notice a problem, notify the teacher immediately.
Materials
Station information sheet
Whale skeleton cards
DNA sequence cards
DNA sequence cladogram
Horse evolution station mat
Horse evolution cards
Glossary
Focus Question: What information can be gained by examining fossil remains of
the ancestors of modern organisms?
Procedures
1.
Discuss the focus question with your teammate(s) and record your answer.
2.
Use the DNA sequence cards and cladogram, horse evolution cards and station
mat, and the whale skeleton cards to answer the questions that follow.
Charles A. Dana Center at The University of Texas at Austin
Student Page 1
Essential Science Concepts for Exit-Level TAKS
Biology Station 7(A)
Evidence of Change
Questions
1. Sequence the whale skeleton cards in order from the oldest fossil to the most
recent skeleton. Justify your answer.
2. What do the fossil remains of earlier whales indicate about changes in the whale’s
habitat over time?
3. If two different species have homologous structures, what can you tell about their
evolutionary history?
4. Locate the DNA sequence cards at the station.
•
Place the shark, camel, and dolphin sequence cards in the appropriate spaces
on the cladogram.
•
Examine the DNA sequences on the remaining cards and compare them to the
shark, dolphin, and camel cards. Determine the correct position of each of the
remaining cards and place them on the cladogram. (The more closely the DNA
sequences match, the more closely related the organisms are to each other.)
•
Record the order of the sequence cards on your copy of the cladogram.
Charles A. Dana Center at The University of Texas at Austin
Student Page 2
Essential Science Concepts for Exit-Level TAKS
Biology Station 7(A)
Evidence of Change
5. Examine the DNA sequence cladogram and determine which organisms are most
closely related based on their homologous structures. Justify your answer.
6. Sometimes organisms that do not have a common ancestor may have anatomical
similarities. These are called analogous structures. Examine the cladogram and
determine which organism(s) share analogous structures with the perch and
shark. Describe the analogous structure(s) and explain why these similarities
could exist in organisms that do not share a common ancestor.
7. Examine the cards that represent the evolution of the modern horse. Arrange the
cards on the horse evolution station mat to show changes that have occurred in
the anatomy of the horse from its most ancient ancestor to modern horses.
Explain why you arranged the cards in the order you selected.
8.
Examine your completed chart that now shows evolutionary changes that have
occurred in the horse’s anatomy over time. Describe the major changes that
you observe.
NOTE: Because other students are going to do the activity after you, be sure to put
all the materials at the station back as you found them. Sometimes there will be
materials that need to be renewed or replaced. If you need assistance or have any
questions, ask your teacher.
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Student Page 3
Essential Science Concepts for Exit-Level TAKS
Biology Station 7(A)
Evidence of Change
Question Card
1.
Obtain the question card from your instructor.
2.
Read the question and discuss the answer with your teammate(s).
3.
Record the team’s consensus in your study folder and justify your answer.
4.
Record the team’s answer on the instructor’s diagnostic wall chart.
I Need to Remember
Complete this part AFTER the class discussion of the station.
I need to remember . . .
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Student Page 4
Essential Science Concepts for Exit-Level TAKS
Biology Station 7(A)
Evidence of Change
Glossary for Biology Station 7(A)
Alleles
Alleles are the alternative forms or variations of the same gene.
Analogous structures
Analogous structures are structures in different species that exhibit anatomical
similarities as a result of adaptations to environmental factors.
Anatomical
Anatomical refers to the structure and organization of an organism.
Cladogram
A cladogram is a tree-like diagram showing evolutionary relationships between
organisms.
Evolution
Evolution is the change in the traits of organisms or populations of organisms
from generation to generation.
Fossil
A fossil is a mineralized remain or preserved impression of an organism that lived
in a past geological time.
Gene pool
The gene pool includes all the genes of a species in a population.
Homologous structures
Homologous structures are structures in different species that exhibit anatomical
similarities as a result of common ancestry.
Physiological
Physiological refers to the functions and biological processes of an organism.
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