Which of the following is found in RNA but not DNA?

• A. Deoxyribose
• B. Double helix structure
• C. Thymine
• D. Uracil

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the structural differences between RNA and DNA. DNA (Deoxyribonucleic Acid) contains the sugar deoxyribose, while RNA (Ribonucleic Acid) contains the sugar ribose. This is one key distinction between the two molecules.
2. Step 2: Recognize the nitrogenous bases present in DNA and RNA. DNA contains adenine (A), thymine (T), cytosine (C), and guanine (G). RNA contains adenine (A), uracil (U), cytosine (C), and guanine (G). Note that thymine is replaced by uracil in RNA.
3. Step 3: Identify the structural differences. DNA is typically double-stranded and forms a double helix structure, while RNA is usually single-stranded and does not form a double helix.
4. Step 4: Focus on the question asking for a feature found in RNA but not DNA. Based on the differences outlined, uracil is unique to RNA and is not found in DNA.
5. Step 5: Conclude that the correct answer is 'Uracil,' as it is the nitrogenous base present in RNA but absent in DNA.