Question

online unit 4 retake: dna, replication, &
the \backbone\ (sides of the ladder) of dna is composed of...
guanine and ribose
phosphate and deoxyribose
deoxyribose and adenine
ribose and phosphate

Explanation:

DNA is a double - helix structure. The backbone (sides of the ladder) is made up of phosphate groups and deoxyribose sugar. Guanine and adenine are nitrogenous bases (rungs of the ladder), not part of the backbone. Ribose is a sugar in RNA, not DNA.

Answer:

phosphate and deoxyribose