(5)Generation and elimination of oxygen free radicals 1)Origin of"2: a mitochondria b. Oxidation of some chemicals in body. C Catalysis by enzymes d stimulation of cells with toxins(5) Generation and elimination of oxygen free radicals 1) Origin of O·- 2： a. Mitochondria b. Oxidation of some chemicals in body. c. Catalysis by enzymes d. Stimulation of cells with toxins