本题目来源于试卷: Unity and Diversity A.2 Nucleic Acids，类别为 IB生物学
[单选题]
How does the genetic code (srbyt(o2xdv l**s))6 wyj zuprovide evemd+h wj6xan8jh9:j.ds m f2 1 *,rcbpidence of universal common ancestry?
A. The genetic code of mitochondria is identical to the genetic code of the nucleus in eukaryotes.
B. Each amino acid is coded for by only one codon.
C. Mutations cannot cause changes in the sequence of bases in the genome.
D. The genetic code is the same across all three domains of life, with just a few exceptions.
参考答案: D
本题详细解析:
The genetic code is lbvxg8y wdo b4-8 1/nggmno0r/argely the same in all known organisms. There are a few exceptions such as mitochondrial DNA which can vary slightly in codon assignments for specific amino acids, and some bacterial species. Therefore Choice D is correct .Choice A is incorrect because the genetic code used in mitochondria is similar to the genetic code used in the nucleus of eukaryotic cells but not entirely the same. Choice B is incorrect because the genetic code is degenerate. There are 64 possible codons in the genetic code, but onmg/v o1 0gog8/by-d wrb84nnx ly 20 amino acids. As a result, some amino acids are coded for by more than one codon, providing redundancy and flexibility in protein synthesis. Choice C is incorrect because mutations are changes in the genetic code. As a result, mutations play a significant role in generating genetic diversity and are a driving force in the process of evolution.
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