本题目来源于试卷: Continuity and Change D.5 Gene Expression，类别为 IB生物学
[单选题]
The rate mRNA is degraded in the cytopl/1. x*ylish+:ctdt1d t qjaa-asm is somu kk2.gkx7 ko8etimes reduced in response to environmental stimuli. How might this mechanism of producing more polypepti kgok kuk.x782des for a given gene increase an individual's fitness?
A. Greater number of polypeptides increases fitness
B. Polypeptide degradation decreases
C. Rate of mRNA synthesis increases
D. Quantity of ATP used per polypeptide synthesised decreases
参考答案: D
本题详细解析:
Choice D is correct because if mRNA persists in the cytoplasm for a longer period of time, less mRNA needs to be synthesised per polypeptide synthesised. mRNA synthesis requires ATP so a reduced need to synthesise mRNA conserves energy which may enhance the organism's chances of reproductive success. Choice A is incorrect because a greater number of polypeptides does not necessarily increase fitness. Choice B is incorrect because a reduced rate of mRNA degradation does not affect the rate polypeptides are degraded. Choice C is incorrect because if mRNA persists in the cytoplasm for longer periods of time, less mRNA needs to be synthesised to replace degraded mRNA.
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