A total of 11 questions are based on the following passage and supplementary ma...
A total of 11 questions are based on the following passage and supplementary material.
This passage is adapted from Richard J. Sharpe and Lisa
Heyden, “Honey Bee Colony Collapse Disorder is Possibly
Caused by a Dietary Pyrethrum Deficiency.” ©2009 by
Elsevier Ltd. Colony collapse disorder is characterized by the
disappearance of adult worker bees from hives.
Honey bees are hosts to the pathogenic large
ectoparasitic mite Varroa destructor (Varroa mites).
These mites feed on bee hemolymph (blood) and can
kill bees directly or by increasing their susceptibility
5 to secondary infection with fungi, bacteria or viruses.
Little is known about the natural defenses that keep
the mite infections under control.
Pyrethrums are a group of flowering plants which
include Chrysanthemum coccineum, Chrysanthemum
10 cinerariifolium, Chrysanthemum marschalli, and
related species. These plants produce potent
insecticides with anti-mite activity. The naturally
occurring insecticides are known as pyrethrums.
A synonym for the naturally occurring pyrethrums is
15 pyrethrin and synthetic analogues of pyrethrums are
known as pyrethroids. In fact, the human mite
infestation known as scabies (Sarcoptes scabiei) is
treated with a topical pyrethrum cream.
We suspect that the bees of commercial bee
20 colonies which are fed mono-crops are nutritionally
deficient. In particular, we postulate that the problem
is a diet deficient in anti-mite toxins: pyrethrums,
and possibly other nutrients which are inherent in
such plants. Without, at least, intermittent feeding on
25 the pyrethrum producing plants, bee colonies are
susceptible to mite infestations which can become
fatal either directly or due to a secondary infection of
immunocompromised or nutritionally deficient bees.
This secondary infection can be viral, bacterial or
30 fungal and may be due to one or more pathogens.
In addition, immunocompromised or nutritionally
deficient bees may be further weakened when
commercially produced insecticides are introduced
into their hives by bee keepers in an effort to fight
35 mite infestation. We further postulate that the proper
dosage necessary to prevent mite infestation may be
better left to the bees, who may seek out or avoid
pyrethrum containing plants depending on the
amount necessary to defend against mites and the
40 amount already consumed by the bees, which in
higher doses could be potentially toxic to them.
This hypothesis can best be tested by a trial
wherein a small number of commercial honey bee
colonies are offered a number of pyrethrum
45 producing plants, as well as a typical bee food source
such as clover, while controls are offered only the
clover. Mites could then be introduced to each hive
with note made as to the choice of the bees, and the
effects of the mite parasites on the experimental
50 colonies versus control colonies.
It might be beneficial to test wild-type honey bee
colonies in this manner as well, in case there could be
some genetic difference between them that affects the
bees’ preferences for pyrethrum producing flowers.
The table above shows, for colonies with colony collapse disorder and for colonies without colony collapse disorder, the percent of colonies having honey bees infected by each of four pathogens and by all four pathogens together.
(7 of 11) The main purpose of the fourth paragraph (lines 42-50) is to
The correct answer is B.
Choice B is the best answer. In the fourth paragraph the authors propose a trial to study if honeybees’ consumption of pyrethrum producing plants helps the honeybees defend against mite infestations. In the experiment, the authors plan to offer honey bee colonies both pyrethrum producing plants and “a typical bee food source such as clover" to determine if these different diets affect the bees' susceptibility to mite infestations.
Choices A, C, and D are incorrect because the main purpose of the fourth paragraph is not to summarize the results of an experiment, provide a comparative nutritional analysis, or predict an outcome of an unfinished experiment.
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