AEMCA Practice Exam

What is cyanide known for?

1. A chemical that evaporates slowly

2. A gas that prevents cells from using oxygen

3. A common nerve agent

4. A colorless liquid used in chemical warfare

The correct answer is: A gas that prevents cells from using oxygen

Cyanide is primarily known for its role as a toxic compound that prevents cells from using oxygen effectively. This occurs because cyanide inhibits cytochrome c oxidase, an essential enzyme in the electron transport chain of cellular respiration. When this enzyme is blocked, oxygen cannot be utilized by the cells, leading to cellular suffocation and ultimately resulting in severe physiological damage or death. While cyanide can take various forms, including gas (hydrogen cyanide) and salts (like potassium cyanide), its defining characteristic in this context is its mechanism of action in disrupting cellular respiration. The other options, while related to aspects of cyanide's characteristics or uses, do not encapsulate its most critical and well-known impact on human physiology, which is its ability to prevent oxygen utilization at the cellular level.