<prompt> Organelle where H2O2 is produced and destroyed is-PeroxisomeLysosomeGolgi bodyRibosome  <response>: Cells have developed many mechanisms to remove free radicals and thereby minimize injury. Free radicals are inherently unstable and decay spontaneously. There are also nonenzymatic and enzymatic systems that contribute to inactivation of free radicals . The rate of decay of superoxide is significantly increased by the action of superoxide dismutases SODs found in many cell types. Glutathione GSH peroxidases are a family of enzymes whose major function is to protect cells from oxidative damage. The most abundant member of this family, glutathione peroxidase 1, is found in the cytoplasm of all cells. It catalyzes the breakdown of H2O2 by the reaction 2 GSH glutathione H2O2 - GS-SG 2 H2O. The intracellular ratio of oxidized glutathione GSSG to reduced glutathione GSH is a reflection of this enzymes activity and thus of the cells ability to catabolize free radicals. Catalase, present in peroxisomes, catalyzes the decomposition of hydrogen peroxide 2H2O2 - O2 2H2O. It is one of the most active enzymes known, capable of degrading millions of molecules of H2O2 per second. Endogenous or exogenous antioxidants e.g., vitamins E, A, and C and b-carotene may either block the formation of free radicals or scavenge them once they have formed. Robbins 9 th edition page no. 15 