Question

Why is double circulation beneficial in human beings?

Answer 1

double circulation keep away from the mixing of the oxygenated and deoxygenated blood
this helps in efficient means of supply of oxygen to our body

Answer 2

The right auricle of heart contracts and passes the deoxygenated blood to the right ventricle, through an auriculo-ventricular aperture (tricuspid valve).
The right ventricle contracts and passes the deoxygenated blood into the two pulmonary arteries, which pumps it to the lungs where the blood is oxygenated. From the lungs, the pulmonary veins transport the oxygenated blood to the left atrium of the heart.

The left atrium contracts and through the auriculo-ventricular aperture (bicuspid valve), the oxygenated blood enters the left ventricle.
The blood passes to aorta from the left ventricle. The aorta gives rise to many arteries that distri.bute the oxygenated blood to all the regions of the body.
Since the blood goes twice through the heart, it is known asdouble circulation.