A plant has a smell of bitter almonds indicating poisoning. Which toxin is most likely?

• A. Carbon Monoxide
• B. Cyanide
• C. Oxygen
• D. Smoke

Answer: (B)

Bitter almond odor is a classic clue for cyanide poisoning because cyanide blocks cellular respiration by inhibiting cytochrome oxidase in mitochondria. Even with oxygen in the blood, cells can’t use it, so tissues become hypoxic quickly, producing rapid deterioration.

Carbon monoxide also causes tissue hypoxia but does not produce that characteristic smell. Oxygen is not a toxin, and smoke is simply a mixture of combustion products; the almond scent specifically points to cyanide exposure rather than smoke exposure in general. So the toxin most likely responsible for the odor is cyanide.