费费-89

89. Rhizobium
bacteria living in the roots of bean plants or other legumes produce fixed
nitrogen, which is one of the essential plant nutrients and which for
non-legume crops, such as wheat, normally must be supplied by applications of
nitrogen-based fertilizer. So if biotechnology succeeds in producing wheat strains
whose roots will play host to Rhizobium bacteria, the need for artificial
fertilizers will be reduced.

The argument above
makes which one of the following assumptions?

(A) Biotechnology
should be directed toward producing plants that do not require artificial
fertilize.

(B) Fixed nitrogen
is currently the only soil nutrient that must be supplied by artificial
fertilizer for growing wheat crops.

(C) There are no
naturally occurring strains of wheat or other grasses that have Rhizobium
bacteria living in their roots.

(D) Legumes are
currently the only corps that produce their own supply of fixed nitrogen.

(E) Rhizobium
bacteria living in the roots of wheat would produce fixed nitrogen.

ans is E but why cant C be the correct ans?

读完题干后的感觉是wheat的根部有legumes一样的某种特性才行

A. 一个建议--无关  B. 不需要限定the only nutrient；D. 与wheat 无关;

剩下C/E：C. 主要是说没有naturally occuring strains，如果题目是要得到必须用biotech方法的结论，那C正确，

现在题目要的结论是通过host RB 减少AF的用量，那么就需要在wheat的根部同样产生FN.

是不是可以说这一题逻辑的本质是： 将一种物体上发生的现象推广到另外一个物体上，

取得同样结果的前提是这两类物体具有必须的相同特质：legumes根部和RB起作用产生FN, wheat 和RB也有同样功能.