Which nitrogenous base is not found in RNA?

• A. Uracil
• B. Thymine
• C. Adenine
• D. Cytosine

Answer: (B)

Verified step by step guidance

1. Recall the four nitrogenous bases found in DNA: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).
2. Recall the four nitrogenous bases found in RNA: Adenine (A), Uracil (U), Cytosine (C), and Guanine (G).
3. Note that RNA contains Uracil instead of Thymine, which is present in DNA.
4. Understand that Thymine is replaced by Uracil in RNA, so Thymine is not found in RNA.
5. Therefore, the nitrogenous base not found in RNA is Thymine.