Florida Biology EOC Practice Test

Nucleic acids are composed of what basic units?

1. Amino acids

2. Fatty acids

3. Nucleotides

4. Sugars

The correct answer is: Nucleotides

Nucleic acids, which include DNA and RNA, are fundamentally made up of nucleotides. A nucleotide consists of three components: a phosphate group, a five-carbon sugar (ribose in RNA and deoxyribose in DNA), and a nitrogenous base (such as adenine, thymine, cytosine, or guanine). These nucleotides link together through covalent bonds between the phosphate group of one nucleotide and the sugar of the next, forming long chains that encode genetic information essential for the functioning and reproduction of living organisms. The other options do not relate to the structure of nucleic acids. Amino acids are the building blocks of proteins, while fatty acids are components of lipids, and sugars are simple carbohydrates. Each of these macromolecules has distinct roles in biological systems, but they do not form nucleic acids. Hence, understanding that nucleotides are the specific units that constitute nucleic acids is crucial in genetics and biochemistry.