Homologous Structures Activity
Name_____________________
Date______________
Period____
Standard(s):
 BI.7 a. Students know why natural selection acts on the phenotype rather than
the genotype of an organism.
 BI. 8. a. Students know how natural selection determines the differential survival
of groups of organisms.
Introduction: The prefix homo- means the same. Homologous structures refer to
structures that have a shared embryonic origin or ancestry. The forelimbs of a human,
the wing of a bird, the wing of a bat and the flipper of the dolphin have the same
embryonic origin during development and they have the same basic bones. Homologous
structures are used as anatomical evidence of evolution.
Procedure:
Part I. Identifying Common Bones
1.) Examine the diagram of the bones of the 6 vertebrate organisms.
2.) Using the human arm as a key locate and label the carpals, ulna , radius, and
humerus bones in each organism.
3.) Using the following coloration key color the bones of each organism its correct
color.
Humerus=Yellow
Carpals=Red
Radius=Blue
Ulna=Green
Part II. Limb Function
1.) Examine the limbs and discuss with your partner the function of each type of
limb.
2.) Cut-out and paste each limb into the correct column in the table on the back of the
sheet.
Follow-up Questions: (Use your book section 10.4 and the reading you received on
homologous structures to answer the questions below.)
1.) What does the presence of homologous structures in the limbs of vertebrates tell
us?
2.) Which of the animals do you think are the most closely related? Why?
3.) How have limbs of the different organisms changed over time?
4.) What is the difference between homologous structures and analogous structures?
Walking/Climbing
Flying
Swimming
Grasping
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