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Mycorrhizal fungi infect more plants than do any other
fungi and are necessary for many plants to thrive,
but they have escaped widespread investigation until
Line recently for two reasons. First, the symbiotic association
5 is so well-balanced that the roots of host plants show
no damage even when densely infected. Second, the
fungi cannot as yet be cultivated in the absence of a
living root. Despite these difficulties, there has been
important new work that suggests that this symbiotic association
10 can be harnessed to achieve more economical use
of costly superphosphate fertilizer and to permit better
exploitation of cheaper, less soluble rock phosphate.
Mycorrhizal benefits are not limited to improved
phosphate uptake in host plants. In legumes,
15 Mycorrhizal inoculation has increased nitrogen
fixation beyond levels achieved by adding phosphate
fertilizer alone. Certain symbiotic associations also
increase the host plant‘s resistance to harmful root fungi.
8. Which of the following most accurately describes
the passage?
(A) A description of a replicable experiment
(B) A summary report of new findings
(C) A recommendation for abandoning a difficult area of research
(D) A refutation of an earlier hypothesis
(E) A confirmation of earlier research
For the following question, consider each of the choices separately and select all that apply
9. It can be inferred from the passage that which of
the following has NOT been a factor influencing the
extent to which research on mycorrhizal fungi has
progressed?
□A Lack of a method for identifying mycorrhizal
fungi
□B Difficulties surrounding laboratory production
of specimens for study
□C Difficulties ensuing from the high cost and
scarcity of superphosphate fertilizers |
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发表于 2011-10-17 10:42:10
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