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Soft-shelled turtles can remain submerged underwater for several hours without ventilating their lungs because __.

• they can store some air in special air sacs under the shell

• they also have rudimentary gills

• they can use cutaneous respiration through the soft lining of their throats

• the partial pressure of oxygen is higher underwater

Anemia is defined as a decrease in the oxygen-carrying ability of the blood, whatever the reason. What are possible causes of anemia? Check all that apply.

• a defect in the synthesis of hemoglobin

• a deficiency of iron in the diet

• a decreased production of nitric oxide by endothelial cells

• abnormally-low production of erythropoietin by the kidneys

In the blood clotting cascade mechanism, which specific enzyme catalyzes the conversion of fibrinogen to fibrin?

• Thrombin

• Renin

• Albumin

• Catalase

• Angiotensin

As compared to the circulatory system of most fishes, the circulatory system of adult amphibians has the advantage of __.

• partially-separate circuits for gas exchange and systemic delivery of blood

• a single circuit

• a pocket of the gut that serves as an air bladder

• a four-chambered heart

• Right ventricle

• Pulmonary arteries

• Pulmonary veins

• Inferior vena cava

• Right atrium