DNA is primarily composed of which type of molecules?

• A. Amino acids
• B. Nucleotides
• C. Monosaccharides
• D. Fatty acids

Answer: (B)

DNA is built from nucleotides, the basic units of nucleic acids. Each nucleotide contains a deoxyribose sugar, a phosphate group, and a nitrogenous base; linking them forms a sugar-phosphate backbone with the bases encoding information in a specific sequence. This polymer structure distinguishes DNA from the other listed types: amino acids build proteins, monosaccharides are the simple units of carbohydrates, and fatty acids are components of lipids. Therefore, the fundamental building block of DNA is nucleotides.