All of the following are vasoconstrictor agents except:

Which of the following is $NOT$ a character of open circulation?

Which of the following is correct regarding blood coagulation?
$I$. Vitamin-$K$ is necessary for the formation of prothrombin.
$II$. Conversion of fibrinogen to fibrin is done by thrombin.
$III$. Conversion of prothrombin to thrombin is done by the enzyme complex prothrombinase.
The option with the correct combination is:

Match the Column-$I$ and Column-$II$.

Column-$I$	Column-$II$
$a.$ Joint diastole	$(i)$ $0.8$ second
$b.$ Heart beat	$(ii)$ All four chambers of heart are relaxed.
$c.$ Cardiac cycle	$(iii)$ $72$ times/min
$d.$ Stroke volume	$(iv)$ $70$ mL

Choose the correct answer from the options given below:

What is the study of the circulatory system called?

Identify the correct option:

Vessel	Renal vein	Pulmonary artery	Hepatic portal vein	Main Aortic arch
$(a)$	$PO_2 = 95 \, mm \, Hg, PCO_2 = 40 \, mm \, Hg$	Less concentration of ions in blood	More fatty acid and glycerol in the blood	$PO_2 = 95 \, mm \, Hg, PCO_2 = 40 \, mm \, Hg$
$(b)$	Blood $pH = 7.4$	Less excretory substances than other blood vessels	More nutritive substances	More oxygen than pulmonary artery
$(c)$	Less excretory wastes	$PO_2 = 40 \, mm \, Hg, PCO_2 = 45 \, mm \, Hg$	Less amount of fatty acid and glycerol compare to other blood vessels	More excretory substances than renal vein
$(d)$	More oxygen than pulmonary artery	More excretory waste than renal vein	$PO_2 = 95 \, mm \, Hg, PCO_2 = 40 \, mm \, Hg$	Less excretory waste than hepatic portal vein