A Levels Biology (9700)•9700/13/O/N/23

Explanation
DNA template stop triplet determines tRNA anticodon sequence Steps:
- Identify the DNA stop triplet ATC as the template strand sequence read 3' to 5' (3'-ATC-5').
- Transcribe to mRNA stop codon: complementary bases yield 5'-UAG-3'.
- Construct tRNA to recognize UAG codon and insert new amino acid.
- Anticodon pairs antiparallel to codon: 3'-AUC-5' (RNA version of DNA template ATC, T→U).
Why B is correct:
- AUC is the 3'-5' anticodon sequence that base-pairs with UAG codon, per Watson-Crick rules.
Why the others are wrong:
- A: ATC is DNA template sequence, not RNA anticodon.
- C: TAG is coding strand DNA for UAG, not anticodon.
- D: UAG is mRNA stop codon, not anticodon.
Final answer: B
Topic: Protein synthesis
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