One of the most noxious wind-borne allergens
is ragweed (Ambrosia). ss evidenced by an esti-
mated 3O million sufferers in the U.S. alone and
a societal cost of over $3 billion. Each plant is
able to produce more than a billion grains of pol-
len over the course of a season, and the plant
is the prime cause of most cases of hay fever
in North America. Although the plant produces
more pollen in wet years. humidity rates above
seventy percent tend to depress the spread of
pollen by causing the grains to clump.
Ragweed spreads rapidly by colonizing re-
cently disturbed soil. such as that engendered
by roads, subdivisions. and cultivation and has
adapted to a multitude of climatic conditions,
including desert and high mountain areas. Com-
plete elimination is virtually impossible. Physi-
cal removal is undone by even one seed or one
bit of root left behind. Ragweed regenerates in
about two weeks from only a half-inch of stem,
usually with additional branching and flowering,
so mowing can actually be counterproductive.
Ragweed is susceptible to only the most ag-
gressive herbicides. and because ragweed tends
to cover large areas, control would mean wide-
spread use of highly toxic chemicals. Control by
natural predators? No known mammal browses
on ragweed. Some species of Lepidoptera (but-
terflies. skippers, and moths) larvae feed on
ragweed, but this arena of control is not well
funded, and consequently not well-researched.
Given the health issues and costs occasioned by
ragweed. government funding for natural control
research is warranted.
Question 18
Consider each of the following answer choices separately and select all that apply.
Which of the following can be inferred about the spread of ragweed pollen?
18. B and C
Choice (A) is not supported, because the passage never compares the rates of pollen production in plants at different climates. Choice
(B) is supported by the phrase mowing can actually be counter productive. Choice (C) is supported by statement that high humidity
rates reduce the spread of ragweed, a wind-borne allergen, by causing the grains to clump. The clumping must have some negative
effect on the wind’s ability to carry the pollen, making choice (C) true.
19. B The answer to this question lies in the line, Some species of Lepidoptera (butterflies, skippers, and moths) larvae feed on ragweed,
but this arena of control is not well funded, and consequently not well-researched. The author mentions the species to indicate that
there may be a potential answer to the problem of controlling ragweed, but this answer has not been fully explored. This most closely
matches choice (B). Choice (A) is wrong because the author doesn’t make a comparison between the methods of control. Choice (C) is
wrong because the species discussed are not mammals. The author does suggest the government explore natural remedies, but choice
(D) doesn’t properly answer the question. The mention of some species of Lepidoptera is not used to plead with the government.
Choice (E) is incorrect because earlier in the passage the author indicates that complete elimination of the ragweed is unlikely.
is ragweed (Ambrosia). ss evidenced by an esti-
mated 3O million sufferers in the U.S. alone and
a societal cost of over $3 billion. Each plant is
able to produce more than a billion grains of pol-
len over the course of a season, and the plant
is the prime cause of most cases of hay fever
in North America. Although the plant produces
more pollen in wet years. humidity rates above
seventy percent tend to depress the spread of
pollen by causing the grains to clump.
Ragweed spreads rapidly by colonizing re-
cently disturbed soil. such as that engendered
by roads, subdivisions. and cultivation and has
adapted to a multitude of climatic conditions,
including desert and high mountain areas. Com-
plete elimination is virtually impossible. Physi-
cal removal is undone by even one seed or one
bit of root left behind. Ragweed regenerates in
about two weeks from only a half-inch of stem,
usually with additional branching and flowering,
so mowing can actually be counterproductive.
Ragweed is susceptible to only the most ag-
gressive herbicides. and because ragweed tends
to cover large areas, control would mean wide-
spread use of highly toxic chemicals. Control by
natural predators? No known mammal browses
on ragweed. Some species of Lepidoptera (but-
terflies. skippers, and moths) larvae feed on
ragweed, but this arena of control is not well
funded, and consequently not well-researched.
Given the health issues and costs occasioned by
ragweed. government funding for natural control
research is warranted.
Question 18
Consider each of the following answer choices separately and select all that apply.
Which of the following can be inferred about the spread of ragweed pollen?
- Ragweed plants adapted to desert and mountain climes tend to spread fewer grains of pollen than do plants in other locations.
- Some attempts to control it may exacerbate the problem.
- The clumping of pollen grains caused by high humidity levels affects the ability of the wind to carry the grains.
Question 19
The author most probably mentions some species of Lepidoptera in order to
The author most probably mentions some species of Lepidoptera in order to
- detail a species that may be more effective at controlling ragweed than are the most aggressive herbicides
- suggest a potential research avenue to the problem of controlling ragweed that is at present poorly explored
- discuss a type of mammal that feeds on ragweed plants and may be successful at controlling the spread of ragweed
- plead with the government to spend more money and put more research efforts into finding a natural control for ragweed
- argue that complete elimination of the ragweed plant will only be possible if the government funds research into natural controls of ragweed
Choice (A) is not supported, because the passage never compares the rates of pollen production in plants at different climates. Choice
(B) is supported by the phrase mowing can actually be counter productive. Choice (C) is supported by statement that high humidity
rates reduce the spread of ragweed, a wind-borne allergen, by causing the grains to clump. The clumping must have some negative
effect on the wind’s ability to carry the pollen, making choice (C) true.
19. B The answer to this question lies in the line, Some species of Lepidoptera (butterflies, skippers, and moths) larvae feed on ragweed,
but this arena of control is not well funded, and consequently not well-researched. The author mentions the species to indicate that
there may be a potential answer to the problem of controlling ragweed, but this answer has not been fully explored. This most closely
matches choice (B). Choice (A) is wrong because the author doesn’t make a comparison between the methods of control. Choice (C) is
wrong because the species discussed are not mammals. The author does suggest the government explore natural remedies, but choice
(D) doesn’t properly answer the question. The mention of some species of Lepidoptera is not used to plead with the government.
Choice (E) is incorrect because earlier in the passage the author indicates that complete elimination of the ragweed is unlikely.
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