Which of the following is the only difference between the nitrogenous bases found in DNA and those found in RNA?

• A. DNA contains ribose, while RNA contains deoxyribose.
• B. DNA contains thymine, while RNA contains uracil.
• C. DNA contains cytosine, while RNA contains guanine.
• D. DNA contains adenine, while RNA does not.

Answer: (B)

Verified step by step guidance

1. Identify the components of nucleotides in both DNA and RNA, focusing on the nitrogenous bases and the sugar molecules.
2. Recall that DNA and RNA both contain adenine (A), guanine (G), and cytosine (C) as nitrogenous bases.
3. Understand that the sugar in DNA is deoxyribose, while in RNA it is ribose; however, this difference relates to the sugar, not the nitrogenous bases.
4. Recognize that the key difference in nitrogenous bases is that DNA contains thymine (T), whereas RNA contains uracil (U) instead of thymine.
5. Conclude that the only difference between the nitrogenous bases in DNA and RNA is the presence of thymine in DNA and uracil in RNA.