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Question Bank [2022] — BIOLOGY STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYQuestion Bank [2022]3 Marks
Question
Write a note on coagulation of blood.
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Answer

  1. Clotting or coagulation is the process of converting the liquid blood into a solid form. This process may be initiated by contact of blood with any foreign surface (intrinsic process) or with damaged tissue (extrinsic process).
  2. Intrinsic and extrinsic processes involve interaction of various substances called clotting factors by a step wise or cascade mechanism.
  3. There are in all twelve clotting factors numbered as I to XIII (factor VI is not in active use). Interaction of these factors occurs in cascade manner leading to formation of the enzyme thrombin.
  4. Thromboplastin helps in the formation of enzyme prothrombinase. This enzyme inactivates heparin and it also converts inactive prothrombin into its active thrombin.
  5. Thrombin converts soluble blood protein fibrinogen into insoluble fibrin. Fibrin forms a mesh in which platelets and other blood cells are trapped to form the clot.

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