A Levels Biology (9700)•9700/13/M/J/25
Explanation
RNA Base Pairing and Codon Recognition in Translation
Steps:
- Evaluate statement 1: tRNA anticodons form complementary base pairs with mRNA codons during translation, enabling amino acid addition to the polypeptide chain.
- Evaluate statement 2: This statement (not provided) is incorrect based on standard RNA biology, as it likely misrepresents a key process.
- Evaluate statement 3: Stop codons (UAA, UAG, UGA) in mRNA lack corresponding tRNA anticodons and instead recruit release factors for translation termination.
- Determine correct choice: Statements 1 and 3 accurately describe RNA functions, while 2 does not.
Why C is correct:
- C selects statements 1 and 3, which align with the mechanism of codon-anticodon pairing and the absence of tRNAs for stop codons.
Why the others are wrong:
- A includes incorrect statement 2.
- B includes incorrect statement 2 but excludes correct statement 3.
- D excludes correct statement 1 but includes incorrect statement 2.
Final answer: C
Topic: Protein synthesis
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