The Food and Drug Administration has recently proposed
severe restrictions on the use of antibiotics to promote the
health and growth of meat animals. Medications added to feeds
kill many microorganisms but also encourage the appearance
of bacterial strains that are resistant to antiinfective drugs.
Already, for example, penicillin and the tetracvlines are not
as effective therapeutically as they once were. The drug
resistance is chiefly conferred by tiny circlets of genes,
called plasmids, that can be exchanged between different strains
and even different species of bacteria. Plasmids are also one
of the two kinds of vehicles (the other being viruses) that
molecular biologists depend of when performing gene transplant
experiments. Even present guidelines forbid the laboratory use
of plasmids bearing genes for resistance to antibiotics. Yet,
while congressional debate rages over whether or not to toughen
these restrictions on scientists in their laboratories, little
congressional attention has been focused on an ill-advised
agricultural practice that produces known deleterious effects.
17. In the passage, the author is primarily concerned with
(A) discovering methods of eliminating harmful microorganisms without subsequently generation drug-resistant bacterial
(B) explaining reasons for congressional inac- tion on the regulation of gene transplant experiments
(C) describing a problematic agricultural prac- tice and its serious genetic consequences
(D) verifying the therapeutic ineffectiveness of anti-infective drugs
(E) evaluating recently proposed restrictions intended to promote the growth of meat animals
18. According to the passage, the exchange of plas- mids between different bacteria can result in which of the following?
(A) Microorganisms resistant to drugs
(B) Therapeutically useful circlets of genes.
(C) Anti-infective drugs like penicillin
(D) Viruses for use by molecular biologists
(E) Vehicles for performing gene transplant experiments
19. It can be inferred from the passage that the author believes that those in favor of stiffening the restrictions on gene transplant research should logically also
(A) encourage experiments with any plasmids except those bearing genes for antibiotic resistance
(B) question the addition of anti-infective drugs to livestock feeds
(C) resist the use of penicillin and tetracyclines to kill microorganisms
(D) agree to the development of meatier live- stock through the use of antibiotics
(E) favor congressional debate and discussion of all science and health issues
20. The author's attitude toward the development of bacterial strains that render antibiotic drugs ineffective can best be described as
(A) indifferent
(B) perplexed
(C) pretentious
(D) insincere
(E) apprehensive |
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