The role of the spleen in mammals is . . . . . . .

Identify the cells and their functions based on the provided figure:
$(a)$ Fig. $A$ - Megakaryocyte - formation of platelets
$(b)$ Fig. $B$ - Lymphocyte - synthesis of antibodies
$(c)$ Fig. $A$ - Eosinophil - secrete antihistamine
$(d)$ Fig. $A$ - Neutrophil - secrete heparin

Where is prothrombin found and what is its function?

$A$ person with an unknown blood group under the $ABO$ system has suffered significant blood loss in an accident and requires an immediate blood transfusion. His friend,who has a valid certificate of his own blood type,offers to donate blood without delay. What would be the blood group of the donor friend?

The protein which prevents coagulation of blood in the blood vessel is

Which of the following cytoplasmic granules contain histamine?