Question

Assertion (A) : In the human heart ventricles have thicker muscular walls than atria. Reason (R) : Ventricles have to pump the blood into various organs.

Which of the following statement (s) is (are) true about human heart ? (a) Right atrium receives oxygenated blood from lungs through pulmonary artery. (b) Left atrium transfers oxygenated blood to left ventricle which sends it to various parts of the body. (c) Right atrium receives deoxygenated blood from different parts of the body through vena cava. (d) Left atrium transfers oxygenated blood to aorta which sends it to different parts of the body.

How many chambered heart is there in birds and mammals?

What are the benefits of it?