Rhizobium bacteria living in the roots of bean

sevengu · 发表于 2011-2-6 15:43:39

Rhizobium bacteria living in the roots of bean plants or other legumes（豆科植物） 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.
oa :e
but i think the choice b is also correct.
if the artificial fertilizer can render other nutrietion desides fixed nitrogen.
then we still need artificial fertilizer ,in turn, it undermines the suggeation that we don't need artificial fertilizer any more. so it should be the assumption.

olin1987 · 发表于 2011-2-6 19:05:13

b 是必要但不充分条件？

sdcar2010 · 发表于 2011-2-6 22:09:10

B is too ristrictive, thus, obviously not an assumption. There might be many other nutrients that wheat plants need.

If you negate B, the conclusion still holds.

pterosaur · 发表于 2011-8-18 13:31:00

Rhizobium bacteria living in the roots of bean plants or other legumes（豆科植物） 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 the need for artificial fertilizers will be reduced.

分析结构，前面提出的如Rhizobium bacteria living in the roots of bean plants or other legumes（豆科植物） 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 nitrogebiotechnology succeeds in producing wheat strains whose roots will play host to Rhizobium bacteria, n-based fertilizer. 都是为了后面由基本的假设推出结论提供支持的东西。假设是biotechnology succeeds in producing wheat strains whose roots will play host to Rhizobium bacteria, 成为了host of bacteria，结论是the need for artificial fertilizers will be reduced。假设和结论直接的bridge is exactly the answer we're looking for. besides, the "only" in B is an obvious symbol of wrong answer.

aqiu41 · 发表于 2011-10-20 11:55:21

第一句话说了两件事儿:
第一件是R bacteria 提供fixed nitrogen 给legumes;
第二件是nitrogen-based fertilizer提供fixed nitrogen 给wheat.

结论是这样的，如果wheat有了R bacteria，fertilizer的需求就会下降。
换句话说，就是R bacteria 要取代nitrogen-based fertilizer。如果要想让这个成立的话，你看一下第一句话交代的第二件事儿，它必须先提供fixed nitrogen才能让那条线成立。

至于B 嘛，我觉得是这样，第一句话后半句还限定了，fixed nitrogen normally must be supplied by applications of nitrogen-based fertilizer。(把第二个which替换成fixed nitrogen，再省去插入语)
B在这句话上加了一个ONLY。所以不对。
我也有点儿晕。。。。。谁能再给讲讲。。。。。。。

viking00x · 发表于 2012-8-22 11:59:15

第一句话说了两件事儿:
第一件是R bacteria 提供fixed nitrogen 给legumes;
第二件是nitrogen-based fertilizer提供fixed nitrogen 给wheat.

结论是这样的，如果wheat有了R bacteria，fertilizer的需求就会下降。
换句话说，就是R bacteria 要取代nitrogen-based fertilizer。如果要想让这个成立的话，你看一下第一句话交代的第二件事儿，它必须先提供fixed nitrogen才能让那条线成立。

至于B 嘛，我觉得是这样，第一句话后半句还限定了，fixed nitrogen normally must be supplied by applications of nitrogen-based fertilizer。(把第二个which替换成fixed nitrogen，再省去插入语)
B在这句话上加了一个ONLY。所以不对。
我也有点儿晕。。。。。谁能再给讲讲。。。。。。。

-- by 会员 aqiu41 (2011/10/20 11:55:21)

但是前面说的nitrogen-based fertilizer和结论中的artificialfertilizers可以默认为等同？？？

ninamikou · 发表于 2012-8-22 12:19:52

我在C和E中犹豫了一下还是选了E
但是我觉得C也是对的呀-->若果有了“naturally occurring strains of wheat or other grasses that have Rhizobium bacteria living in their roots” 那么“biotechnology“就不用去发明了啊，说明已经success了。这算是一个assumption么？
我发现好多CR都有这种选项每回都要犹豫望NN解答~

Rhizobium bacteria living in the roots of bean

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