Although field studies have linked inbreeding to declines among song sparrow populations, some researchers argue that, in nature, inbreeding proves ___ as a factor when compared with crushing blows from weather changes.
A.hazardous
B.momentous
C.trivial
D.significant
E.precarious
F.inconsequential
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The author implies that all of the following statements about duplicate artifacts are true EXCEPT__
A．A market for such artifacts already exists.
B．Such artifacts seldom have scientific value.
C．There is likely to be a continuing supply of such artifacts.
D．Museums are well supplied with examples of such artifacts.
E．Such artifacts frequently exceed in quality those already catalogued in museum collections. -
The author quotes Snyder et al in lines 38-43 most probably in order to__
A．reveal some of the assumptions underlying their theory
B．summarize a major finding of their experiments
C．point out that their experiments were limited to the mouse
D．indicate that their experiments resulted only in general correlations
E．refute the objections made by supporters of the older theory -
LONGYEARBYEN, Norway — With plant species disappearing at an alarming rate, scientists and governments are creating a global network of plant banks to store seeds and sprouts, precious genetic resources that may be needed for man to adapt the world？ s food supply to climate change.
This week, the flagship of that effort, the Global Seed Vault near here, received its first seeds, millions of them. Bored into the middle of a frozen Arctic mountain topped with snow, the vault？ s goal is to store and protect samples of every type of seed from every seed collection in the world.
As of Thursday, thousands of neatly stacked and labeled gray boxes of seeds — peas from Nigeria, corn from Mexico — reside in this glazed cavelike structure, forming a sort of backup hard drive, in case natural disasters or human errors erase the seeds from the outside world.
Descending almost 500 feet under the permafrost, the entrance tunnel to the seed vault is designed to withstand bomb blasts and earthquakes. An automated digital monitoring system controls temperature and provides security akin to a missile silo or Fort Knox. No one person has all the codes for entrance.
The Global Vault is part of a broader effort to gather and systematize information about plants and their genes, which climate change experts say may indeed prove more valuable than gold. In Leuven, Belgium, scientists are scouring the world for banana samples and preserving their shoots in liquid nitrogen before they become extinct. A similar effort is under way in France on coffee plants. A number of plants, most from the tropics, do not produce seeds that can be stored.
For years, a hodgepodge network of seed banks has been amassing seed and shoot collections in a haphazard manner. Labs in Mexico banked corn species. Those in Nigeria banked cassava. Now these scattershot efforts are being urgently consolidated and systematized, in part because of better technology to preserve plant genes and in part because of the rising alarm about climate change and its impact on world food production.
“We started thinking about this post-9/11 and on the heels of Hurricane Katrina,” said Cary Fowler, president of the Global Crop Diversity Trust, a nonprofit group that runs the vault. “Everyone was saying, why didn？ t anyone prepare for a hurricane before？ We knew it was going to happen.“Well, we are losing biodiversity every day — it？ s a kind of drip, drip, drip. It？ s also inevitable. We need to do something about it.”
This week the urgency of the problem was underscored as wheat prices rose to record highs and wheat stores dropped to the lowest level in 35 years. A series of droughts and new diseases cut wheat production in many parts of the world. “The erosion of plants？ genetic resources is really going fast,” said Dr. Rony Swennen, head of the division of crop biotechnology at the Catholic University of Leuven in Belgium, who has preserved half of the world？ s 1,200 banana types. “We？ re at a critical moment and if we don？ t act fast, we？ re going to lose a lot of plants that we may need.”
The United Nations International Treaty on Plant Genetic Resources, ratified in 2004, created a formal global network for banking and sharing seeds, as well as for studying their genetic traits. Last year, its database received thousands of new seeds.
A system of plant banks could be crucial in responding to climate crises since it could identify genetic material and plant strains better able to cope with a changed environment.
Here at the Global Vault, hundreds of gray boxes containing seeds from places ranging from Syria to Mexico were moved this week into a freezing vault to be placed in suspended animation. They harbor a vast range of qualities, like the ability to withstand drier, warmer climate. -
The theory mentioned in line 1 relates to the conceptual models discussed in the passage in which of the following ways？
A．It may furnish a valid account of ore-forming processes, and, hence, can support conceptual models that have great practical significance.
B．It suggests that certain geological formations, long believed to be mineralized, are in fact mineralized, thus confirming current conceptual models.
C．It suggests that there may not be enough similarity across Archean-age gold-quartz vein systems to warrant the formulation of conceptual models.
D．It corrects existing theories about the chemical halos of gold deposits, and thus provides a basis for correcting current conceptual models.
E．It suggests that simple prospecting methods still have a higher success rate in the discovery of gold deposits than do more modern methods. -
According to the passage, researchers working under the two-category hypothesis were correct in thinking that__
A．prokaryotes form. a coherent group
B．the common ancestor of all living things had complex properties
C．eukaryotes are fundamentally different from true bacteria
D．true bacteria are just as complex as eukaryotes
E．ancestral versions of eukaryotic genes functioned differently from their modern counterparts.