Which of the following is the primary building block (monomer) of nucleic acids?

• A. Amino acid
• B. Fatty acid
• C. Monosaccharide
• D. Nucleotide

Answer: (D)

Verified step by step guidance

1. Understand the structure and function of nucleic acids: Nucleic acids, such as DNA and RNA, are macromolecules responsible for storing and transmitting genetic information. Their structure is composed of repeating units called monomers.
2. Identify the monomer of nucleic acids: The primary building block (monomer) of nucleic acids is the nucleotide. Nucleotides are composed of three components: a phosphate group, a pentose sugar (either ribose or deoxyribose), and a nitrogenous base (adenine, guanine, cytosine, thymine, or uracil).
3. Compare the given options: Amino acids are the building blocks of proteins, fatty acids are components of lipids, and monosaccharides are the monomers of carbohydrates. None of these are involved in the structure of nucleic acids.
4. Recognize the correct answer: Based on the structure and function of nucleic acids, the correct monomer is the nucleotide, as it is the fundamental unit that forms the backbone and base-pairing structure of DNA and RNA.
5. Conclude the reasoning: Nucleotides are the only option that matches the definition of a monomer for nucleic acids, making them the correct answer to the question.