Ontario Grade 12 University Biology (SBI4U) Practice Exam 2026 – All-in-One Study Guide for Ace Success!

DNA and RNA share similarities in their nucleotide structure, specifically in the types of nitrogenous bases they contain. Both nucleic acids feature adenine (A) and guanine (G) as purines. These two bases play essential roles in the coding and decoding of genetic information.

Though DNA primarily exists as a double-stranded helix and RNA typically is single-stranded, the presence of the shared purines highlights a fundamental similarity in their molecular structure. This commonality is critical in various biological processes, including transcription and translation, where the genetic code is expressed.

The fact that DNA utilizes deoxyribose while RNA uses ribose means they do not share the same pentose sugar, so that option would not be accurate. Additionally, while both can participate in coding for proteins, their specific roles differ, and not all RNA types (like rRNA and tRNA) directly code for proteins.