One coiled spring is shown in the diagram. A teacher modeled part of a DNA molecular using two of these coiled springs. Which part of the DNA molecule was the teacher most likely modeling?

A. Protein

B. Gene

C. Nitrogen base

D. Backbone

The teacher was most likely using the Backbone.

The correct answer will be option D (Backbone).

Explanation:

DNA is a large molecule made up of monomer units called nucleotides and serves the function of genetic material of organisms.

Each nucleotide is made up of 5-C sugar (deoxyribose), phosphate group (PO₄³⁻) and nitrogenous bases (adenine, cytosine, guanine and thymine). Sugar and phosphate molecule forms the backbone of the DNA while nitrogenous bases are stacked perpendicular to the backbone which pair with another complimentary base by hydrogen bonds forming a double helical structure of DNA in organisms.

Since teacher was modeling the DNA with the coiled springs, she was modeling the backbone of the DNA formed of sugar and phosphate which twists after every 10 bp or 3.4 nm length.

Thus, option D is the correct answer.