A Levels Biology (9700)•9700/13/M/J/20
Explanation
Uracil Nucleotide Properties Steps:
- Identify uracil as a base in RNA nucleotides, distinguishing it from DNA.
- Recall uracil is a pyrimidine base that pairs with adenine via hydrogen bonds.
- Evaluate statements based on RNA specificity: uracil replaces thymine in RNA.
- Confirm correct statements align with uracil's role in RNA structure and function.
Why B is correct:
- B (1 and 2 only) matches uracil's definition as a pyrimidine in RNA, excluding thymine-related DNA facts.
Why the others are wrong:
- A includes all three, but statement 3 likely errs on DNA pairing or thymine confusion.
- C omits key RNA fact in 2, focusing on irrelevant 1 and 3.
- D skips pyrimidine base in 1, pairing incorrect aspects.
Not enough information on exact statements 1–3.
Final answer: B
Topic: Structure of nucleic acids and replication of DNA
Practice more A Levels Biology (9700) questions on mMCQ.me