What is the correct order of events occurring in blood clotting?
$I.$ Conversion of fibrinogen to fibrin
$II.$ Formation of clot
$III.$ Thromboplastin formation
$IV.$ Conversion of prothrombin to thrombin
Choose the correct option.

Which of the following statements are wrong?
$(i)$ Leucocytes disintegrate in the spleen and liver.
$(ii)$ $RBC$,$WBC$ and blood platelets are produced by bone marrow.
$(iii)$ Neutrophils bring about destruction and detoxification of toxins of protein origin.
$(iv)$ The important function of lymphocytes is to produce antibodies.

Which organ is responsible for the storage of blood to be released during sudden blood loss?

Select the correct option regarding the clotting of body fluids in a test tube.

Describe the events in the cardiac cycle. Explain 'double circulation'.

Consider the following four statements regarding the human circulatory system:
$(a)$ Arteries have thick walls and have a smaller lumen compared to veins.
$(b)$ Angina is a sudden chest pain.
$(c)$ In the $ABO$ blood grouping system,a person with $AB$ blood group can donate blood to anyone.
$(d)$ Calcium ions play an important role in blood clotting.
Which two of the above statements are correct?