Fill the empty boxes with suitable answers with respect to the valves of a mammalian heart.

Valve(s)	Location	Function
Bicuspid valve or mitral valve	A	Prevents the backward flow of blood from left ventricle to left auricle
B	At the right auricular ventricular aperture	Regulates the flow of blood from right auricle to right ventricle
Aortic valve	At the base of Aorta	C
Semilunar valve	D	Regulates the flow of blood from right ventricle to pulmonary artery

Hint: There is a difference in the number of chambers present in heart, in different animals. The amphibians consist of three chambered hearts, except for the crocodile. And the mammalian heart consists of four chambered hearts. For the regulation of flow of blood in the heart, various valves are located in the mammalian heart. The blood keeps flowing correctly due to the four valves that are present in each chamber of the heart.

Complete step by step answer:
The valves which are located at the upper and lower heart chambers are mitral and tricuspid valves, respectively. The valves which are present in between some major blood vessels that are leaving the heart and the ventricles are pulmonic and aortic valve.
The bicuspid valve helps in prevention of backward blood flow into the left auricle, and that is the reason it is situated at the aperture of the left auricle and ventricle. The tricuspid valve helps in regulation of blood flow into the right ventricle from the right auricle, and that is the reason it is present at the aperture of the right auricle and ventricle. The aortic valve helps in regulating the blood flow to all the body parts, and that is the reason it is present near the aortic artery base. The semilunar valve helps in regulation of blood flow in the pulmonary artery from the right ventricle, and that is the reason it is situated in between the pulmonary trunk and the right ventricle.
The following is the table showing the different valves, their location and function-



Note:
In most animals, the heart is a muscular organ that helps in pumping the blood in the circulatory system of animals. The arteries carry the oxygenated blood from the heart to other organs. On the other hand, the veins carry the deoxygenated blood from other organs to the hearts.