2. An adaptive advantage of having a three-chambered heart, as found in amphibians, over the two-chambered heart of fish is thatA. there are capillary beds in both the respiratory organ and body systems of amphibians but not fish. B. the additional chamber in the amphibian heart reduces blood flow to the respiratory organ. C. fully oxygenated blood returning to the amphibian heart can undergo additional pumping to reach higher pressures. D. fully oxygenated blood is kept completely separate from relatively deoxygenated blood in the heart. E. amphibians can tolerate higher environmental pressures.

fully oxygenated blood returning to the amphibian heart can undergo additional pumping to reach higher pressures.

Explanation:

Fishes have a two-chambered heart with one atrium and one ventricle. The blood is pumped from the atrium into the ventricle. Ventricle pumps blood into a single circuit of blood vessels. Blood is oxygenated as it passes through capillaries in the gills. As blood circulates through the gill capillaries, it has low blood pressure and therefore, is delivered very slowly to the other organs.

The amphibian heart has two atria and one ventricle. A sinus venosus collects oxygen-poor blood and pumps it into the right atrium. Oxygenated blood from the lungs passes directly into the left atrium. The left atrium pumps the oxygen-rich blood into the arteries that conduct it to the various tissues of the body. Therefore, a three-chambered heart in reptiles allows the delivery of oxygenated blood with high blood pressure.