Name _______________________
#_______
Comparing Limb Structure and Function
Could you tell if two people were related just by looking at them? What kinds of
evidence would help you determine their relationship? In this lab, you will observe
parts of various animals and look for evidence that these animals are related to
one another.
OBJECTIVES
Observe and describe the limb structures of different organisms.
Identify relationships between the structures of different organisms.
MATERIALS
• pen or pencil
PROCEDURE
1. Observe the forelimbs of the animals shown in Figure 1. Count the approximate number of bones in each of the upper and lower limbs. Record this data in
Table 1. Then record the function of each limb.
FIGURE 1. FRONT LIMBS OF DIFFERENT ANIMALS
Upper bone
Frog front leg
Human arm
Lower bone
Whale flipper
Bat wing
Dog front leg
Bird wing
Penguin flipper
Alligator front leg
Comparing Animal Limbs
Structure Number of
bones in
upper limb
Structure Number of
bones in
lower limb
Function of limb
Frog
Whale
Dog
Penguin
Human
Bat
Bird
Alligator
Analysis and Conclusions
1. Examining Data Observe the arrangement of bones in each animal.
Compare these observations with the number of bones in each limb. How are
the limbs (structure) of these animals similar?
How are these limbs different?
2. Classifying Look again at the data collected. Classify the animals according
to the functions of the limbs.
3. Drawing Conclusions Which is a better indicator of the relationship between
two organisms – structure or function?
Explain your reasoning.
Name _______________________
#_______
Key
Comparing Limb Structure and Function
Could you tell if two people were related just by looking at them? What kinds of evidence
would help you determine their relationship? In this lab, you will observe parts of various
animals and look for evidence that these animals are related to one another.
OBJECTIVES
Observe and describe the limb structures of different organisms.
Identify relationships between the structures of different organisms.
MATERIALS
• pen or pencil
PROCEDURE
1. Observe the forelimbs of the animals shown in Figure 1. Count the approximate
number of bones in each of the upper and lower limbs. Record this data in Table 1.
Then record the function of each limb.
FIGURE 1. FRONT LIMBS OF DIFFERENT ANIMALS
Upper bone
Frog front leg
Human arm
Lower bone
Whale flipper
Bat wing
Dog front leg
Penguin flipper
Bird wing
Alligator front leg
Comparing Animal Limbs
Frog
Structure Number of
bones in
upper limb
Structure Number of
bones in
lower limb
3
3
13
27
Hopping, moving, swimming
swimming
3
18
Walking, digging
3
8
Swimming
3
3
26
Around 16
flying
3
7
flying
3
20
Walking, swimming
Function of limb
Whale
Dog
Penguin
Grasping, holding
Human
Bat
Bird
Alligator
Analysis and Conclusions
4. Examining Data Observe the arrangement of bones in each animal.
Compare these observations with the number of bones in each limb. How
are the limbs (structure) of these animals similar?they all have 3 bones in
the upper limb
How are these limbs different?they have different numbers of bones in
lower limbs and the limbs have different functions
5. Classifying Look again at the data collected. Classify the animals
according to the functions of the limbs.swimming-frogs, whales, penguin,
alligator
walking-dog, alligator, frog
flying-bat, bird
grasping-human
6. Drawing Conclusions Which is a better indicator of the relationship
between two organisms – structure or function? Structure because when
you classify according to function bats and birds are in the same class but
bats are mammals and birds are not. If you classify according to structure
then all the mammals above are shown to have close to same # of bones
which indicates they are closely related.
Explain your reasoning.