What does a decrease in the number of blood platelets lead to?

Which $\text{WBCs}$ are phagocytic cells that destroy foreign organisms entering the body?

Fibrins are formed by the conversion of inactive fibrinogens in the plasma by the enzyme........

$A$ certain road accident patient with unknown blood group needs immediate blood transfusion. His one doctor friend at once offers his blood. What was the blood group of the donor?

$A$ person with an unknown blood group ($ABO$ system) has lost a large amount of blood in an accident and needs an immediate blood transfusion. $A$ friend of the person has a valid certificate of their own blood group and is ready to donate blood without delay. What could be the blood group of the donor friend?

Persons with $AB$ blood group can accept blood from persons of ........... blood group and the antibody in their blood plasma is.......