Practice question

Amphibian heart three-chambered architecture comprises two separate atria left atrium receiving oxygenated blood from pulmonary veins and cutaneous veins, right atrium receiving deoxygenated systemic venous blood via sinus venosus, and single undivided ventricle with trabeculae carneae and spiral valve within conus arteriosus partially directing streams reducing mixing. Systemic and pulmocutaneous circuits partially overlapping, less efficient than four-chambered avian mammalian. Sinus venosus and truncus arteriosus prominent embryonic remnants persisting, reflecting transition between two-chambered fish heart and fully septated amniote heart. This concept holds high importance for NEET, CBSE board, CUET and competitive examinations focusing on comparative