Which of the following statements best supports the claim that organisms share fundamental processes as a result of evolution?

Question

BlackTom AI · Accepted Answer

The universality of the genetic code—three-nucleotide codons specifying amino acids—directly supports common ancestry: organisms can often express each other’s genes because the same codons map to the same amino acids.

1. Relevant knowledge points and concepts
- The genetic code is organized in triplet codons (64 possible codons) that specify 20 amino acids plus start/stop signals.
- The central dogma: DNA → RNA → protein; translation machinery (ribosomes, tRNAs) reads codons to build polypeptides.
- A universal code implies descent from a last universal common ancestor (LUCA). Experimental evidence includes production of human insulin in bacteria and expression of GFP in many species.
- Exceptions are rare (mitochondrial code variants) and do not negate the overall universality.

2. Step-by-step reasoning
- If disparate organisms use the same codon-to-amino-acid mapping, then the mechanism for encoding proteins is conserved.
- Conservation of such a complex, information-rich system is best explained by shared evolutionary origin rather than independent invention.
- Practical demonstration: genes transferred between species are often expressed and functional, showing the code’s compatibility across life.

3. Intermediate steps (no numerical calculations required)
- Codons: 4 nucleotides^3 = 64 possible codons; redundancy (degeneracy) means multiple codons can encode the same amino acid.
- Translation uses tRNA anticodons and ribosomes; these molecular components are sufficiently conserved to interpret foreign mRNA.

4. Why the correct answer is correct
- The statement that “All organisms share a genetic code organized into triplet codons, making it possible for one organism to express a gene from another organism” is a direct molecular-level demonstration of shared fundamental processes and common descent.

5. Why other options are incorrect
- Option 2: Not all organisms use oxygen; many anaerobes derive energy without O2, so oxygen usage is not universal.
- Option 3: Chloroplasts and mitochondria exist only in eukaryotes (prokaryotes lack these organelles), so the claim “all organisms possess” is false.
- Option 4: Introduced organisms do not always fill vacant ecological roles; many fail or become invasive without filling a specific niche.

6. Conclusion
The universal triplet genetic code is the strongest support among the choices for shared fundamental processes due to evolution. Final answer: All organisms share a genetic code organized into triplet codons, making it possible for one organism to express a gene from another organism.

Which of the following statements best supports the claim that organisms share fundamental processes as a result of evolution?单项选择题

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