Student Wrap Up
Topic: Evidence of Evolution
Part II: Homologous and Analogous Structures
Benchmark SC.912.L.15.1 Explain how the scientific theory of evolution is supported by the fossil record,
comparative anatomy, comparative embryology, biogeography, molecular biology, and observed evolutionary
change.
Background Information: Body parts in different organisms that have the same basic structure are called
homologous structures. By comparing homologous structures, biologists can determine how organisms are
related. The presence of homologous structures suggests that organisms evolved from a common ancestor.
Prelab Questions:
1. Differentiate between the terms “homologous” and “analogous”.
2. What term can be used to describe a screw, nail and staple?
Materials: Paper, Pencil
Procedure
1. Refer to Figure 1. Carefully examine the relative size, shape, number, and position of the bones in the body
parts shown.
2. Using Data Table 1, Indentify the body part shown for each organism listed. Describe the function of each
body part. Record the information into the data table.
3. Refer to Figure 2. Compare the structure of a bird wing and a butterfly wing shown in the drawing
Adapted from Globe Biology, copyright 1990[Type text]
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Diagram Sheet
.
Adapted from Globe Biology, copyright 1990[Type text]
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Student Wrap-Up
Record Sheet
Prelab Questions:
1. Differentiate between the terms “homologous” and “analogous”.
2. What term can be used to describe a screw, nail and staple?
Data Table 1
Organism
Homologous Structures
Body Part
Function
Human
Horse
Cat
Bat
Bird
Whale
Questions
1. How are the body parts shown in Figure 1 alike? . How are they different?
2. Do the body parts in Figure 2 have similar or different structures?
3. Do the body parts in figure 2 have similar or different functions?
4. Why are the structures shown in Figure 1 homologous structures?
5. Why are the structures shown in Figure 2 analogous structures?
6. How do the arm of a human and the flipper of a whale show evidence of an evolutionary relationship?
7. Do the wings of a bird and a butterfly suggest an evolutionary relationship? How do you know?
Adapted from Globe Biology, copyright 1990[Type text]
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Teacher Wrap- Up
Topic: Homologous and Analogous Structures
Benchmark SC.912.L.15.1 Explain how the scientific theory of evolution is supported by the fossil record,
comparative anatomy, comparative embryology, biogeography, molecular biology, and observed evolutionary
change.
Background Information
There are many forms of evidence for evolution. One of the strongest forms of evidence is
comparative anatomy; comparing structural similarities of organisms to determine their evolutionary
relationships. Organisms with similar anatomical features are assumed to be relatively closely related
evolutionarily, and they are assumed to share a common ancestor. As a result of the study of
evolutionary relationships, anatomical similarities and differences are important factors in determining
and establishing classification of organisms.
Some organisms have anatomical structures that are very similar in embryological development and
form, but very different in function. These are called homologous structures. Since these structures
are so similar, they indicate an evolutionary relationship and a common ancestor of the species that
possess them. A clear example of homologous structures is the forelimb of mammals. When
examined closely, the forelimbs of humans, whales, dogs, and bats all are very similar in structure.
Each possesses the same number of bones, arranged in almost the same way. While they have
different external features and they function in different ways, the embryological development and
anatomical similarities in form are striking. By comparing the anatomy of these organisms, scientists
have determined that they share a common evolutionary ancestor and in an evolutionary sense, they
are relatively closely related.
Materials: Card Stock, Scissors
Instructions
1. Copy the diagram sheet on to cardstock and cut out each diagram for the lab station.
2. Place an instruction sheet and the cut-outs at the lab station.
3. Each student will need to have a copy of the Record Sheet or have the students copy the information from a single
copy placed at the lab station.
Answers to Questions
Prelab Questions:
1. Differentiate between the terms “homologous” and “analogous”.
Adapted from Globe Biology, copyright 1990[Type text]
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Homologous structures have similar structures but different functions. Analogous are similar in function but
don’t have similar shapes.
2. What term can be used to describe a screw, nail and staple? Analogous
Organism
Body Part
Function
Human
arm
Picking up things
Horse
Leg
Walking
Cat
Leg
Walking
Bat
Wing
Flying
Bird
Wing
Flying
Whale
Fin
Swimming
Questions
1. How are the body parts shown in Figure 1 alike? They have similar bones .How are they different?
2. Do the body parts in Figure 2 have similar or different structures? The bones are different in shape and size.
3. Do the body parts in figure 2 have similar or different functions? They have similar structures.
4. Why are the structures shown in Figure 1 homologous structures? They have different functions
5. Why are the structures shown in Figure 2 analogous structures? The structures are similar in structure but
differ in function
6. How do the arm of a human and the flipper of a whale show evidence of an evolutionary relationship? The
arm and the flipper have similar bones which can indicate a common ancestor.
7. Do the wings of a bird and a butterfly suggest an evolutionary relationship? How do you know? No, the
structures do not share any similar parts.
Adapted from Globe Biology, copyright 1990[Type text]
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