Final answer:
The correct statement for how DNA is structured like a ladder is: Sugar-phosphate backbones make up the sides of the ladder, connected by covalent bonds, while the nitrogenous bases form the rungs, connected by hydrogen bonds, with the correct answer being (a) Sugar-phosphate, covalent, nitrogenous bases, hydrogen.
Step-by-step explanation:
DNA is often compared to a ladder, where the sides of the ladder are made up of sugar-phosphate backbones connected by covalent bonds, and the rungs of the ladder are comprised of nitrogenous bases connected by hydrogen bonds.
This analogy helps to visualize DNA's double helix structure, where the sugar-phosphate backbones are the outer framework of the DNA molecule, and the nitrogenous bases (adenine, thymine, cytosine, and guanine) pair up in the interior to form the steps of this molecular ladder.
To answer the student's question, the correct statement is: DNA is said to be like a ladder where sugar-phosphate connected by covalent bonds make up the sides of the ladder and the nitrogenous bases connected by hydrogen bonds make up the rungs of the ladder. Therefore, the correct answer is (a) Sugar-phosphate, covalent, nitrogenous bases, hydrogen.