Answer: The PT and APTT are valuable blood clotting time determination principles.
Step-by-step explanation:
The principle of PT or prothrombin test determines the time required for the clot formation when additional calcium factor is added.
The principle of APTT or activated partial thromboplastin time is a test which determines the time required for the formation of the blood clot after the adding the calcium and phospholipid factors. This process activates the different blood clotting factors in the blood responsible for clotting of blood.