Explain the chemical events that take place to form a blood clot to seal the wound.
Chemical events that take place to form a blood clot are as follows
(i) When blood comes out of a blood vessel, the platelets clump together, break and release platelet factors, thromboplastin.
(ii) The enzyme thrombokinase initiates the conversion of prothrombin into thrombin.
(iii) Thrombin thus, catalyses the conversion of fibrinogen into fibrin which forms a mesh/network in which blood cells get entangled.
(iv) ${{Ca}^{2+}}$ ions are necessary for both the above steps.