Which of the following animals has the highest heart rate?

The pacemaker of the heart is known as ........

Given below are two statements.
Statement $I$ - The heart sound $Dub$ is heard during ventricular diastole.
Statement $II$ - The heart sound $Lubb$ is heard during atrial systole.
In the light of above statements,select the correct option given below:

Contraction of the right ventricle of the human heart pumps blood into the......

Mixing up of arterial and venous blood does not take place in a heart having

What are the values of stroke volume and cardiac output under normal conditions?
Stroke Volume $\quad$ Cardiac Output