Question

The base which is present in DNA but not in RNA is:

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

Hint:

DNA = A, G, C, T RNA = A, G, C, U Remember: Thymine (T) is replaced by Uracil (U) in RNA.

Answer 1

The Correct Option is C

To determine which base is present in DNA but not in RNA, we need to understand the basic structure of nucleic acids.

DNA (Deoxyribonucleic Acid) and RNA (Ribonucleic Acid) are composed of nucleotides, each containing a sugar, a phosphate group, and a nitrogenous base. The nitrogenous bases are classified into two categories:

• Pyrimidines: Cytosine, Thymine (exclusive to DNA).
• Purines: Adenine, Guanine.

In RNA, thymine is replaced by another pyrimidine, uracil. Thus, the bases in RNA are adenine, guanine, cytosine, and uracil.

Therefore, the base that is present in DNA but not in RNA is Thymine.

Let's examine why the other options are incorrect:

• Guanine: This base is present in both DNA and RNA.
• Cytosine: This base is present in both DNA and RNA.
• Adenine: This base is present in both DNA and RNA.

Hence, the correct answer is Thymine, as it is the base found in DNA but not in RNA.