What are free radicals?

• A. Compounds that change how something works
• B. Inert gases
• C. Large molecules used for energy
• D. Enzymes that speed reactions

Answer: (A)

Free radicals are atoms or molecules that carry an unpaired electron, which makes them highly reactive. That reactivity allows them to alter chemical processes by stealing or sharing electrons with other molecules, potentially changing how reactions proceed and damaging essential cellular components like lipids, proteins, and DNA. In the body, this can contribute to disease when radicals accumulate, though they also play roles in normal signaling and immune defense in controlled amounts. They are not inert gases, which are nonreactive; they are not large energy-giving molecules, which are fuels like fats and carbohydrates; and they are not enzymes, which are proteins that accelerate reactions. So, they are best described as compounds that change how chemical processes work.