The invasion of the land by amphibians posed a number of challenges requiring evolutionary innovations. Which one of the following does NOT match a challenge with a corresponding adaptation found in amphibians?

Question

A.  The force of gravity was greater without water's buoying effect, selecting for well-muscled legs.
B.  Additional oxygen was needed for larger muscles, selecting for the partially-divided heart and pulmonary circuit.
C.  Eggs dry out in a terrestrial environment, selecting for the amniotic egg.
D.  Gills tend to collapse out of the water, selecting for lungs and cutaneous respiration.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?

Gather Content
· What do you already know about amphibian adaptations to land?

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

A.  The force of gravity was greater without water's buoying effect, selecting for well-muscled legs.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses amphibian adaptations to land.
· What type of thinking is required?
        o This question is asking you to take what you already know and apply it to this unfamiliar situation.

Gather Content
· What do you already know about amphibian adaptations to land?
        o The successful invasion of land by amphibians posed a number of major challenges:
        o Because amphibian ancestors had relatively large bodies, supporting the body’s weight on land as well as enabling movement from place to place was a challenge. Legs evolved to meet this need.
        o The delicate structure of fish gills requires the buoyancy of water to support them, and they cannot function in air. Therefore, other methods of obtaining oxygen were required.
        o Delivering great amounts of oxygen to the larger muscles needed for movement on land required modifications to the heart and circulatory system.
        o Reproduction still had to be carried out in water so that eggs would not dry out.
        o The body itself had to be prevented from drying out.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Of all the features listed, only the amniotic egg is not a feature of amphibians.
        o Reptiles were the first amniotes, because they were the first to lay their eggs out of the water.

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that amphibians lay their eggs in water?
        o Did you remember that reptiles first evolved the amniotic egg, not amphibians?