Final answer:
The four-chambered heart in birds and mammals improves the efficiency of double circulation, ensuring that oxygen-rich blood is effectively distributed to the body while deoxygenated blood is sent to the lungs. This allows these animals to have higher metabolic rates and maintain a constant body temperature.
Step-by-step explanation:
The benefit of a four-chambered heart in birds and mammals is that it improves the efficiency of double circulation and is likely necessary for their warm-blooded lifestyle. The four chambers of the heart allow for the separation of oxygenated and deoxygenated blood, ensuring that oxygen-rich blood is effectively distributed to the body while deoxygenated blood is sent to the lungs to be oxygenated again.
By having a four-chambered heart, the circulatory system can deliver oxygen and nutrients to tissues more efficiently, enabling these animals to have higher metabolic rates and maintain a constant body temperature. Without this separation, oxygen-rich and oxygen-poor blood would mix in the heart, reducing the efficiency of oxygen transport throughout the body and hindering the animals' ability to sustain their high-energy lifestyles.