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OG2022 - 762
In an attempt to produce a coffee plant that would yield beans containing no caffeine, thesynthesis of a substance known to be integral to the initial stages of caffeine production wasblocked either in the beans, in the leaves, or both. For those plants in which synthesis of thesubstance was blocked only in the leaves, the resulting beans contained no caffeine.
Any of the following, if true, would provide the basis for an explanation of the observedresults EXCEPT:
A. In coffee plants, the substance is synthesized only in the leaves and then moves to thebeans, where the initial stages of caffeine production take place.
B. In coffee plants, the last stage of caffeine production takes place in the beans using acompound that is produced only in the leaves by the substance.
C. In coffee plants, the initial stages of caffeine production take place only in the beans,but later stages depend on another substance that is synthesized only in the leaves anddoes not depend on the blocked substance.
D. In coffee plants, caffeine production takes place only in the leaves, but the caffeinethen moves to the beans
E. Caffeine was produced in the beans of the modified coffee plants, but all of it moved tothe leaves, which normally produce their own caffeine.
正确答案是C
一个是不懂block in是指什么,是让物质直接留在叶子里?还是从叶子里去除这个物质?尤其是怎样block in both beans and leaves这个是什么意思?
其次是看了答案以后再读选项仍然不是特别明白这个逻辑,可能还是block in没完全理解的缘故
求大神指点!
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