Which of the following is an example of a biological toxin?

• A. Mustard gas
• B. Ricinin
• C. Carbon monoxide
• D. Acyanide

Answer: (B)

The correct answer is ricin, which is a highly toxic compound derived from the seeds of the castor oil plant. It is classified as a biological toxin because it is produced by living organisms and can wreak havoc on cellular processes. Ricin inhibits protein synthesis within cells, leading to cell death and can cause severe illness or even death if ingested, inhaled, or injected.

In contrast, mustard gas, while toxic, is a chemical weapon rather than a biological toxin. It is a synthetic compound used in warfare that causes severe chemical burns and respiratory distress. Carbon monoxide is a colorless, odorless gas that is toxic primarily due to its ability to bind with hemoglobin and disrupt the oxygen-carrying capacity of the blood; it is also not defined as a biological toxin. Acyanide, likely referring to cyanide, is another chemical toxin that affects cellular respiration by inhibiting cytochrome c oxidase in the mitochondria but is not classified as a biological product.

Therefore, ricin stands out as an example of a biological toxin due to its origin and mechanism of toxicity, distinguishing it from the other options listed.