Question

Four chambered heart is present in
A. Frog
B. Crocodile
C. Shark
D. Lizard

Answer 1

Heart is a muscular organ present behind and left to the breastbone. It performs the functions of pumping oxygenated blood to the body parts, pumping deoxygenated blood to lungs for oxygenation, pumping of hormones, and to maintain blood pressure. It pumps blood through arteries and veins.

Complete answer: Four chambered hearts are present in crocodiles. Four chambers present are namely two atria and two ventricles connected to the right and left aorta. Heart have heart valves that direct the blood flow in one direction. This is an unusual trait shown by crocodiles, unlike other reptiles. Four chambered heart is an adaptation in a crocodile to minimize oxygen loss when they are present underwater by reducing the heartbeat by 2-3 minutes and as they come to the surface heartbeat is normalized again. Two types of blood do not mix due to the presence of four chambers.
-Frogs have a three-chambered heart consisting of one ventricle and two atria. Both atria drain their blood to the single ventricle. Both oxygenated and deoxygenated blood mixes up in the ventricle. Blood from the ventricle then enters body circulation.
-Sharks have a single circulatory system having a two-chambered heart. Blood flows to gills from the heart for oxygenation. This oxygenated blood is then transported to the body tissues.
-Lizards also have a three-chambered heart having left and right atria with a single ventricle. It only has a partial interventricular septum and it channels oxygenated blood to the body and deoxygenated blood to the pulmonary trunk.
Hence, the correct answer is Option B.

Note: Reptiles mainly have 3 chambered heart. The exception is the crocodile which has 4 chambered heart consisting of right and left atria and right and left ventricle. Left and right atria are connected by a hole known as Foramen of Panizza. Heart valves are also present to direct the flow of blood in a single direction.