Question

Heart of bird is ………………… chambered.
A. One
B. Two
C. Three
D. Four

Answer 1

As we have learnt till now that birds fall in order Aves of Vertebrates and they have a very efficient cardiovascular system that permits them to meet the metabolic demand of flight. They possess a complete separation of oxygenated blood and deoxygenated blood.

Complete answer:
As we know that fishes or Pisces possesses two chambered having one auricle and one ventricle that only pumps deoxygenated blood, Amphibians and Reptiles possess three chambered heart that is two auricles and one common ventricle where right auricle receives deoxygenated blood and left auricle receives oxygenated blood and both the types gets mixed in single ventricle.
Aves or birds consists of a very efficient cardiovascular system which basically permits them to meet the metabolic demand of flight. The cardiovascular system helps in delivering the oxygen to body cells as well as maintain the temperature of the body of birds.
Like mammals, birds also have a four-chambered heart with two atria and two ventricles that help in complete separation of oxygenated blood and deoxygenated blood.
Blood moves from Right auricle to the right ventricle across the tricuspid valves. Right ventricle then pumps the blood to Lungs through the pulmonary trunk.
Pulmonary veins then bring the oxygenated blood back to the left auricle and blood then moves from the left auricle to the left ventricle across the Bicuspid valve.
Left ventricle then pumps the blood to the entire body through Aorta.
This phenomenon of flow of blood is called double circulation.

Hence, from the above explanation the correct answer is (D).

Note:
Pisces heart is called Venus heart as it only pumps the deoxygenated blood and Amphibians and Reptiles heart pumps out mixed blood. Crocodiles are the exception in reptiles as they possess a four chambered heart like Aves and mammals.
Aves also possess some flightless birds class called Ratitae that includes Struthio, Apteryx, Casurius and Dromains.