NEET 2022 Zoology question on Evolution

1. A.
   The atrio-ventricular node (AVN) generates an action potential to stimulate atrial contraction
2. B.
   The tricuspid and the bicuspid valves open due to the pressure exerted by the simultaneous contraction of the atria
3. C.
   Blood moves freely from atrium to the ventricle during joint diastole.
4. D.
   Increased ventricular pressure causes closing of the semilunar valves.

[NEET 2022]