Question

The heart of a crocodile consists of
 A. A single auricle and two ventricles
 B. Two auricles and a single ventricle
 C. Two auricles and two ventricles
 D. A single auricle and a single ventricle

Answer 1

Hint: Crocodile belongs to class Reptilia, which are considered as the first mammals on land with ability to live and reproduce on land. Most of them have four legs like appendages, that is they are tetrapods.

Complete answer:
First let’s understand different types of hearts in vertebrates.
Two-chambered heart: Mostly present in fishes, these consist of one auricle and one ventricle. Single circulation of blood occurs. Blood enters atria and is passed on to the ventricle that pushes blood to all organs.
Three-chambered heart: Found in reptiles and amphibians It consists of two auricles and one ventricle. Double circulation of blood occurs, it pumps blood more vigorously and with more pressure to organs. Mixing of oxygenated and deoxygenated blood occurs sometime.
Four-chambered heart: Found in Mammals, consist of two auricles and two ventricles. Deoxygenated Blood from the whole body enters the heart through the vena cava in the right atrium and is passed into the right ventricle through tricuspid valves after which it reaches lungs where it gets oxygenated. Oxygenated blood is passed on to the pulmonary vein which carries it to the left atrium passing on to the left ventricle. Aorta carries oxygenated blood to body parts.
Crocodile is the only reptile which has a four-chambered heart.

Correct answer here would be option C two auricles and two ventricles.

Note:
Crocodiles have dry, non-glandular skin and epidermal scales. In addition, they are cold-blooded animals, oviparous hence these are features of reptiles with only the exception of a 4-chambered heart.