How does cyanide cause cell death in the body?

• A. Inhibits DNA replication
• B. Inhibits glycolysis
• C. Interferes with anaerobic metabolism
• D. Blocks calcium channels

Answer: (C)

Cyanide blocks the mitochondrial electron transport chain, specifically inhibiting cytochrome oxidase. This stops oxidative phosphorylation, so cells can’t produce ATP using oxygen. With aerobic energy production halted, cells are forced to rely on anaerobic glycolysis, which is inefficient and leads to lactic acidosis and cellular energy failure, especially in tissues with high energy demand. This disruption of energy production is why the best-fitting choice describes interference with anaerobic metabolism—the body becomes dependent on a shortcut pathway that cannot sustain life. The other options don’t match cyanide’s mechanism: it doesn’t directly inhibit DNA replication, glycolysis isn’t blocked (it’s still used but cannot meet energy needs without mitochondria), and it doesn’t primarily affect calcium channels.