题目内容
What occurred during the four centuries of attempted European conquest in
the Americas merely extended the continuum of history into a new arena. The
successes of these new arrivals and their descendants, consistent with the
Line historical tendencies in human behavior, came at the expense of people whose
(5) kinship-based tribal system still operated on communitarian, if exclusive,
principles. Only the tribes of the southern hemisphere had become fully settled
and had entered into their own era of empire-building. Unfortunately, the
European people had achieved both technological and organizational superiority
as these characteristics applied to the art of warfare whereas the tribes of the
(10) southern hemisphere had numbers in their favor but had no time for the adoption
of European weaponry or strategy, a situation that contrasted sharply with that
in North America where the tribes gained considerable access to modern
weapons and were more flexible in their strategies. The two most important
advantages the European-Americans possessed in the north was the endless
(15) stream of migration that more than replaced the population lost during warfare,
and a production system centered in large and relatively secure population
centers.
It can be inferred from the passage that from a historical perspective, the European conquest of the Americas can be viewed as
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SECTION 3
Directions: Each passage in this group is followed by questions based on its content. After reading a passage, choose the best answer to each question. Answer all questions following a passage on the basis of what is stated or implied in the passage.
Scientists have long speculated as to the extent that inbreeding contributes
to the decline and eventual extinction of large assimilated populations, most
agreeing that in natural populations the impact of inbreeding depression on
Line population survival is insignificant in comparison to that of demographic and
(5) environmental variables. While there is ample evidence of fitness reduction due
to inbreeding depression in captivity, no field studies on natural populations
have been conducted to test the proposed effect on extinction.
However, Saccheri recently found in his study of a large metapopulation of
the Glanville .fritillary butterfly that extinction risk increased significantly
(10) with decreasing heterozygosity, an indication of inbreeding, even after
accounting for the effects of the relevant ecological factors. Rate of maturation,
larval survival, adult longevity and egg-hatching rate were found to be adversely
affected by inbreeding, and appear to be the fitness components underlying the
relationship between inbreeding and extinction. One wonders, nevertheless,
(15) how applicable these results would be to the increasing number of species with
small isolated populations due to habitat loss and fragmentation.
Which of the following best describes the organization of the passage？
It can be inferred from the passage that Goethe's scientific contemporaries made which of
If the phenomenon "extinction risk increased significantly with decreasing heterozygosity"
SECTION 1
Directions: Each sentence below has one or two blanks, each blank indicating that something has been omitted. Beneath the sentence are five lettered or sets of words. Choose the word or set of words for each blank that best fits the meaning of the sentence as a whole.
In the newly discovered gene, the change of a single unit of DNA converts the worm from a solitary forager into______diner.
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