You dissect a specimen of a vertebrate during an anatomy laboratory. It has the following characteristics: lungs, abundant blood capillaries under thin skin, a partially-divided heart, a pulmonary circuit, and four walking legs. What is this animal?

Question

A.  lungfish
B.  amphibian
C.  reptile
D.  placental mammal
E.  marsupial mammal

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 amphibians?

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.  amphibian

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses amphibians.
· 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 amphibians?
        o Amphibians include frogs, salamanders, and the wormlike, nearly blind organisms called caecilians.Amphibians have several key characteristics in common:
        o 1. Legs. Frogs and most salamanders have four legs and can move about on land quite well.
        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.
        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 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 Could the animal be a lungfish? No, they don’t have four proper walking legs.
        o Could the animal be a reptile? No, they don’t have thin skin with abundant capillaries. Their skin is covered with scales.
        o Could the animal be a placental or marsupial mammal? No, they have a fully-divided, four-chambered heart.
        o Could the animal be an amphibian? Yes. Amphibians respire partly through their skin, and they lack scales, so their skin is thin and there are abundant capillaries underneath for gas exchange.

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 respire partially through their skin?