Question

In which vertebrate oxygenated and deoxygenated blood get mixed?
A. Fish
B. Amphibian
C. Birds
D. Mammal

Answer 1

The circulatory system is also called the cardiovascular system, which is an organ system that allows the circulation of blood and other nutrients throughout the whole body, which provides all cells and tissues with necessary nutrition and nourishment.

Complete answer: Vertebrates are the groups of animal species that possess spinal cord in the cartilaginous or bone structure that form vertebrae which further make the spine, it found in birds, fish, mammals, reptiles and amphibians. The mixing of oxygenated blood and deoxygenated blood leads to the forming of partially oxygenated blood that circulates throughout the body. To make oxygenated blood from the deoxygenated blood, it needs the help of lungs where blood is converted into oxygenated blood by releasing carbon dioxide. The mixing of both oxygenated and deoxygenated blood is found in amphibian and most reptile animals, due to the presence of 2 or 3 chambered hearts which is incapable of preventing mixing of oxygenated and deoxygenated blood. Fish heart consists of two-chambered that is named as one auricle and one ventricle, the heart has well-developed sinus venosus and conus arteriosus. Birds have four-chambered hearts, and sinus venosus is absent, RBC is nucleated, oval and biconvex and renal portal system is reduced.
Mammals have well developed four-chambered hearts that circulate oxygenated and deoxygenated blood without mixing it and also show double circulation of blood in humans. RBC is non-nucleated.
Hence the correct option is B.

Note: Crocodile is the only reptile which has a four-chambered heart which is a unique feature in this reptile and can live inside water for more than twenty minutes in the single breath which is an evolutionary feature of this animal.