Final answer:
DNA is composed of smaller units called nucleotides, which include a nitrogenous base, a pentose sugar, and a phosphate group. The correct answer to the DNA composition question is A. Nucleotides.
Step-by-step explanation:
DNA is a long molecule carrying genetic information crucial for the functioning and reproduction of living organisms. DNA is composed of smaller subunits known as nucleotides. Each nucleotide, the fundamental building block of DNA, consists of three components: a nitrogenous base, a pentose sugar, and a phosphate group.
The correct answer to the student's question is A. Nucleotides. Amino acids, proteins, and enzymes are all important biological molecules, but they are not the components that make up the DNA molecule. Instead, amino acids are the building blocks of proteins, which are synthesized according to the genetic code carried by DNA.
DNA's structure is a double helix, where the sequence of its four types of nitrogenous bases—adenine (A), thymine (T), guanine (G), and cytosine (C)—encodes the genetic instructions. These instructions are essential for cell functions and are transferred from parents to offspring, providing the basis for inherited characteristics.