Which statement about DNA and RNA is correct?

• A. RNA contains uracil and is usually single-stranded, whereas DNA contains thymine and is usually double-stranded.
• B. DNA is typically single-stranded and serves as the direct template for protein synthesis at ribosomes, whereas RNA is double-stranded and stores genetic information long-term.
• C. Both DNA and RNA contain thymine as a nitrogenous base.
• D. RNA uses deoxyribose sugar and DNA uses ribose sugar.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the basic structural differences between DNA and RNA. DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are nucleic acids that differ in sugar type, nitrogenous bases, and strand structure.
2. Step 2: Recall that DNA contains the sugar deoxyribose, while RNA contains ribose. This difference in sugar affects the stability and function of each molecule.
3. Step 3: Identify the nitrogenous bases present in each molecule. DNA contains adenine (A), thymine (T), cytosine (C), and guanine (G). RNA contains adenine (A), uracil (U), cytosine (C), and guanine (G). Note that RNA uses uracil instead of thymine.
4. Step 4: Consider the strand structure: DNA is usually double-stranded forming a double helix, whereas RNA is usually single-stranded, allowing it to fold into various shapes for different functions.
5. Step 5: Use these facts to evaluate each statement and determine which one correctly describes the differences between DNA and RNA.