CR - Soil Nutrient

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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 fertilizer.

(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 crops that produce their own supply of fixed nitrogen.

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

The OA is E.am confused between B and E
B- Using LEN, if fixed nitrogen is not the only nutrient taht needs to be supplied b the fertilizer, the use of artificial fertilizer will not go down

Please suggest

When its asked to determine assumption made in the argument, always look for missing link.

bacterias living in beans produce nitrogen which is good for growth > wheats dont produce such nitrogen, hence need fertilizers
> science makes wheat roots to act as host for these bacterias > <missing link, will the bacteria on wheat produce nitrogen??> > no fertilizer necessary

(A) Biotechnology should be directed toward producing plants that do not require artificial fertilizer. >> should be? No assumptin made here. Incorrect

(B) Fixed nitrogen is currently the only soil nutrient that must be supplied by artificial fertilizer for growing wheat crops. >> Extra info, extra premises, may be used to stregthen the arg, not an assumption, incorrect

(C) There are no naturally occurring strains of wheat or other grasses that have Rhizobium bacteria living in their roots. >> not an assumption, wrong

(D) Legumes are currently the only crops that produce their own supply of fixed nitrogen. >> extra info(E) Rhizobium bacteria living in the roots of wheat would produce fixed nitrogen. >> satisfies missing link. Correct

IMO e

are you sure the answer is E??? what is the source of this qs?? Even I think the answer is B.
conclusion is 'artificial fertillizer use will be reduced' because 'rhizobium in roots willprodce nitrogen'
missing link is something like 'fertillizers are source of nitrogen ONLY

I think the assumption in E is a safe assumption.....rhizobium bacteria produces bacteria....whether they are in roots of legumes or wheat or in a lab dish it doesnt matter.....

Interesting question! Let’s see if I can help

So devinawilliams83 – your question seems to be why is (B) not an assumption the argument makes.

You negate answer (B) – “If fixed nitrogen is not the only nutrient that needs…”

If this negation is true, then the argument holds true. So let’s take explore the negated statement.

Say that wheat is also unable to produce compressed oxygen without the aid of artificial fertilizers. At the same time farmers are able to produce wheat that can host rhizobium. Clearly the need for nitrogen-based fertilizer will be reduced.
Sure, the wheat will still use fertilizer to help it produce compressed oxygen, but its presence – along with any other fertilizers – does not bear on whether nitrogen-based fertilizer is reduced.

I think the confusing part in the paragraph is “the need for artificial fertilizers will be reduced.” The argument is not saying that the need for ALL artificial fertilizers but simply the need for a nitrogen-based one.


The major assumption of course is that rhizobium living in wheat – as opposed to their natural legume environment – will be able to produce fixed nitrogen. If this is not the case, then the entire argument falls apart. Wheat will still need artificial fertilizer to produce fixed nitrogen.

Hope that made sense ☺.

IMO the assumption tht nitrogen is the only nutrient in fertillizers is the bigger assumption....I mean its common knowlede that it is NOT so.....dont you think so? I dont like the question...it seems to have two equally weighty assumption.....and its quite subjective to the reader what appears to be the 'bigger' assumption.....