Name



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 Lower bone

Frog front leg Whale flipper Dog front leg Penguin flipper

Human arm Bat wing Bird wing Alligator front leg

Comparing Animal Limbs

| |Structure - |Structure - | |

| |Number of bones in |Number of bones in | |

| |upper limb |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 Lower bone

Frog front leg Whale flipper Dog front leg Penguin flipper

Human arm Bat wing Bird wing Alligator front leg

Comparing Animal Limbs

| |Structure - |Structure - | |

| |Number of bones in |Number of bones in | |

| |upper limb |lower limb |Function of limb |

| | | | |

| | | | |

|Frog |3 |13 |Hopping, moving, swimming |

| |3 |27 |swimming |

|Whale | | | |

| |3 |18 |Walking, digging |

|Dog | | | |

| |3 |8 |Swimming |

|Penguin | | | |

| | | |Grasping, holding |

|Human |3 |26 | |

| |3 |Around 16 |flying |

|Bat | | | |

| |3 |7 |flying |

|Bird | | | |

| |3 |20 |Walking, swimming |

|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.

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