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propensity to cause frost damage, thereby rendering it safer than the phytopathogen from which it
was derived.
Some proponents have gone further and suggest that genetic alteration techniques could
create organisms with totally new combinations of desirable traits not found in nature. For example,
genes responsible for production of insecticidal compounds have been transposed from other
bacteria into pseudomonads that colonize corn roots. Experiments of this kind are diffi cult and
require great care: such bacteria are developed in highly artifi cial environments and may not
compete well with natural soil bacteria. Nevertheless, proponents contend that the prospects for
improved agriculture through such methods seem excellent. These prospects lead many to hope that
current efforts to assess the risks of deliberate release of altered microorganisms will successfully
answer the concerns of opponents and create a climate in which such research can go forward
without undue impediment.
Adapted from: soal _sbmptn_soshum.com

1. Which one of the following best summarizes the main idea of the passage?
A. Recent fi eld experiments with genetically altered Pseudomonas bacteria have shown
that releasing genetically altered bacteria into the environment would not involve any
signifi cant danger.
B. Encouraged by current research, advocates of agricultural use of genetically altered
bacteria are optimistic that such use will eventually result in improved agriculture,
though opponents remain wary.
C. Current research indicates that adding genetically altered Pseudomonas syringae
bacteria to the soil surrounding crop plant roots will have many benefi cial effects, such
as the prevention of frost damage in certain crops.
D. Genetic alteration of a number of harmful phytopathogens has been advocated by
many researchers who contend that these techniques will eventually replace such
outdated methods as crop rotation.
E. Genetic alteration of bacteria has been successful in highly artifi cial laboratory
conditions, but opponents of such research have argued that these techniques are
unlikely to produce organisms that are able to survive in natural environments.

2. The author discusses naturally occurring Pseudomonas fluorescens bacteria in the first
paragraph primarily in order to do which one of the following?
A. prove that increases in the level of such bacteria in the soil are the sole cause of soil
suppressivity
B. explain why yields increased after wheat fields were sprayed with altered Pseudomonas
fl uorescens bacteria
C. detail the chemical processes that such bacteria use to suppress organisms parasitic to
crop plants, such as wheat, sugar beets, and potatoes
D. provide background information to support the argument that research into the
agricultural use of genetically altered bacteria would be fruitful
E. argue that crop rotation is unnecessary, since diseases brought on by phytopathogens
diminish in severity and eventually disappear on their own

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