Cyanide poisoning causes death in seconds because - (1) It denatures enzymes of the heart/muscle (2) It breaks the electron transport chain (3) It causes Lysis of red blood cells (4) It causes cardiac arrest
(4) It causes cardiac arrest Explanation: Cyanide poisoning occurs on exposure to a com-pound that produces cyanide ions when dissolved in water. The cyanide ion halts cellular respiration by inhibiting an enzyme in the mitochondria called cytochrome c oxidase. If cyanide is inhaled it causes a coma with seizures, apnea, and cardiac arrest, with death following in a matter of seconds.