Which statement did the Miller-Urey experiment demonstrate about early Earth chemistry?

• A. Organic molecules such as amino acids
• B. Nucleic acids
• C. Proteins
• D. Minerals

Answer: (A)

The point being tested is whether simple inorganic materials on early Earth could be transformed into organic molecules without life. The Miller-Urey experiment showed that amino acids, the building blocks of proteins, can be synthesized from a mixture of simple gases (like water, methane, ammonia, and hydrogen) when energized by sparks that simulate lightning. This demonstrated that organic molecules needed for life could arise from nonliving chemistry under plausible early-Earth conditions. It’s important to note that the experiment produced amino acids, not nucleic acids or proteins themselves, and not minerals, so it illustrates the formation of basic organic building blocks rather than complex biomolecules or inorganic materials.