The single ventricle in an amphibian heart means the oxygenated and deoxygenated blood mix. How do amphibians manage to survive despite this inefficiency?

Question

A.  The absorb large amounts of fluid.
B.  They transport oxygen across the skin.
C.  They keep their body temperatures high.
D.  They move very slowly.
E.  They keep gills into adulthood.

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 features?

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

B.  They transport oxygen across the skin.

Clarify Question

· What is the key concept addressed by the question?
        o This question addresses amphibian features.
· 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 features?
        o Living amphibians have several key characteristics in common:
        o 1. Legs. These were one of the key adaptations to life on land.
        o 2. Lungs. Most amphibians possess a pair of lungs, although the internal surfaces have much less surface area than do reptilian or mammalian lungs. Amphibians breathe by lowering the floor of the mouth to suck in air, and then raising it back to force the air down into the lungs.
        o 3. Cutaneous respiration. Frogs, salamanders, and caecilians all supplement the use of lungs by respiring directly through their skin, which is kept moist and provides an extensive surface area for gas exchange.
        o 4. Pulmonary veins. After blood is pumped through the lungs, two large veins called pulmonary veins return the aerated blood to the heart for repumping. In this way aerated blood is pumped to the tissues at a much higher pressure.
        o 5. Partially divided heart. A dividing wall helps prevent aerated blood from the lungs from mixing with nonaerated blood being returned to the heart from the rest of the body. The blood circulation is thus divided into two separate paths: pulmonary and systemic. The separation is imperfect, however, because no dividing wall exists in one chamber of the heart, the ventricle.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o One reason that amphibians manage despite a heart that is less efficient than a reptile’s or mammal’s is that they use cutaneous respiration – that is, they can acquire oxygen through their skin.
        o A few species of amphibians do retain gills into adulthood, but most do not, so this explanation isn’t as powerful.

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 living amphibians can get some oxygen directly through their skin?