If a dna molecule was a spiral staircase, what would the steps of the staircase be?

Nitrogenous bases

Explanation:

DNA is a nucleic acid molecule that acts as the genetic material of the organisms. The structure of DNA is made of two strands of nucleotides that are linked together and form a helical structure. The helical structure is known as the double-helical model with a ladder-like appearance.

The backbone of the ladder is composed of the sugar and phosphate groups at alternate positions whereas the staircase of the ladder are made of the different type of nitrogenous bases (A, G, T, C)  joined by the hydrogen bond.

Thus, Nitrogenous bases is the correct answer.

hey, i believe your answer would be d. sugar ribose and the base uracil. i believe this is the answer, because rna consists of sugar ribose, adenine, guanine, cytosine, and uracil.

your first option is incorrect, because that's dna. where it consists of sugar deoxyribose, adenine, guanine, cytosine and thymine.

your second option is also incorrect, this is because sugar deoxyribose is in dna, and uracil is in rna. these two do not make sense together.

your third option being incorrect, because sugar ribose is in rna, but not the base of thymine. rna consists of uracil, not thymine.

lastly your fourth option being correct! this answer is correct, because both sugar ribose, and the base uracil are in rna! ~

answer is d. sugar ribose and the base uracil.