"Hidden" Species May Be Surprisingly CommonCryptic species animals that appear identical but are genetically quite distant—may be much more widespread than previously thought. The findings could have major implications in areas ranging from biodiversity estimates and wildlife management, to our understanding of infectious diseases and evolution.Reports of cryptic species have increased dramatically over the past two decades with the advent of relatively inexpensive DNA sequencing technology. Markus Pfenninger and Klaus Schwenk, of the Goethe-Universitat, in Frankfurt, Germany, analyzed all known data on cryptic animal species and discovered that they are found in equal proportions throughout all major branches of the animal kingdom and occur in equal numbers in all biogeographieal regions.Scientists had previously speculated that cryptic species were predominantly found in insects and reptiles, and were more likely to occur in tropical rather than temperate regions. "Species that are seemingly widespread and abundant could in reality be many different cryptic species that have low populations and are highly endangered. " Says Pfenninger. Until the genetic information of all species in at least one taxon is thoroughly studied, no one will know just how many cryptic species exist. "It could be as high as 30%. " Pfenninger says."I'm extremely surprised by their results. " Says Alex Smith of the University of Guelph in Ontario, Canada. "It's a call to arms to keep doing the broad kind of genetic studies that we are doing. "Sampling as many individuals as possible, scientists hope to complete work on all fish and birds in another 5 to 10 years. Once either of these taxonomic groups is completed, Pfenninger says researchers will be able to decide how many cryptic species exist throughout the animal kingdom.Examples of cryptic species include the African elephant. A 2001 study found the elephants were actually two genetically distinct, non-interbreeding species, the African bush elephant and the African elephant. The species are currently listed as vulnerable and threatened, respectively, by the World Conservation Union (WCU).The reclassifications are more than an academic exercise. They define populations that have evolved independently of each other and whose genetic differences can have significant consequences. In the early 1900s misidentification of mosquito species based on morphology confused attempts to control malaria in Europe. Ultimately, what was thought to be a single species was actually made up of six sibling species, only three of which transmitted the disease. "The basic unit in biology is always the species, and you have to know what you are dealing with. " Pfenninger says. Much previous research is now no longer used, he says, because it is not clear what species was being studied.Which of the following about the significance of the research on cryptic species is NOT true?A．The results of the research can help the development of many other research areas.B．The results of the research can help the development of biodiversity estimates.C．The results of the research can help our understanding of infectious disease evolution.D．The results of the research can help our understanding of "survival of the fittest. "
"Hidden" Species May Be Surprisingly Common
Cryptic species animals that appear identical but are genetically quite distant—may be much more widespread than previously thought. The findings could have major implications in areas ranging from biodiversity estimates and wildlife management, to our understanding of infectious diseases and evolution.
Reports of cryptic species have increased dramatically over the past two decades with the advent of relatively inexpensive DNA sequencing technology. Markus Pfenninger and Klaus Schwenk, of the Goethe-Universitat, in Frankfurt, Germany, analyzed all known data on cryptic animal species and discovered that they are found in equal proportions throughout all major branches of the animal kingdom and occur in equal numbers in all biogeographieal regions.
Scientists had previously speculated that cryptic species were predominantly found in insects and reptiles, and were more likely to occur in tropical rather than temperate regions. "Species that are seemingly widespread and abundant could in reality be many different cryptic species that have low populations and are highly endangered. " Says Pfenninger. Until the genetic information of all species in at least one taxon is thoroughly studied, no one will know just how many cryptic species exist. "It could be as high as 30%. " Pfenninger says.
"I'm extremely surprised by their results. " Says Alex Smith of the University of Guelph in Ontario, Canada. "It's a call to arms to keep doing the broad kind of genetic studies that we are doing. "
Sampling as many individuals as possible, scientists hope to complete work on all fish and birds in another 5 to 10 years. Once either of these taxonomic groups is completed, Pfenninger says researchers will be able to decide how many cryptic species exist throughout the animal kingdom.
Examples of cryptic species include the African elephant. A 2001 study found the elephants were actually two genetically distinct, non-interbreeding species, the African bush elephant and the African elephant. The species are currently listed as vulnerable and threatened, respectively, by the World Conservation Union (WCU).
The reclassifications are more than an academic exercise. They define populations that have evolved independently of each other and whose genetic differences can have significant consequences. In the early 1900s misidentification of mosquito species based on morphology confused attempts to control malaria in Europe. Ultimately, what was thought to be a single species was actually made up of six sibling species, only three of which transmitted the disease. "The basic unit in biology is always the species, and you have to know what you are dealing with. " Pfenninger says. Much previous research is now no longer used, he says, because it is not clear what species was being studied.
Which of the following about the significance of the research on cryptic species is NOT true?
A．The results of the research can help the development of many other research areas.
B．The results of the research can help the development of biodiversity estimates.
C．The results of the research can help our understanding of infectious disease evolution.
D．The results of the research can help our understanding of "survival of the fittest. "
相关考题：
Which of the following about the African bush elephant and the African elephant is true?A．The WCU are interbreeding those elephants.B．They are interbreeding species.C．They are two genetically distant species.D．They depend on each other for survival.
CWe have met the enemy, and he is ours. We bought him at a pet shop. When monkey-pox, a disease usually found in the African rain forest, suddenly turns up in children in the American Midwest, it’s hard not to wonder if the disease that comes from foreign animals is homing in on human beings. “Most of the infections (感染) we think of as human infections started in other animals,” says Stephen Morse, director of the Center for Public Health Preparedness at Columbia University.It’s not just that we’re going to where the animals are; we’re also bringing them closer to us. Popular foreign pets have brought a whole new disease to this country. A strange illness killed Isaksen’s pets, and she now thinks that keeping foreign pets is a bad idea. “I don’t think it’s fair to have them as pets when we have such a limited knowledge of them,” says Isaksen.“Laws allowing these animals to be brought in from deep forest areas without stricter control need changing,” says Peter Schantz. Monkey-pox may be the wake-up call. Researchers believe infected animals may infect their owners. We know very little about these new diseases. A new bug (病毒) may be kind at first. But it may develop into something harmful (有害的). Monkey-pox doesn’t look a major infectious disease. But it is not impossible to pass the disease from person to person.64. We learn from Paragraph 1 that the pet sold at the shop may _________.A. come from ColumbiaB. prevent us from being infectedC. enjoy being with children D. suffer from monkey-pox
EA rainforest is an area covered by tall trees with the total high rainfall spreading quite equally through the year and the temperature rarely dipping below l6℃．Rainforests have a great effect on the world environment because they can take in heat from the sun and adjust the climate．Without the forest cover，these areas would reflect more heat into the atmosphere，warming the rest of the world. Losing the rainforests may also influence wind and rainfall patterns，potentially causing certain natural disasters all over the world．In the past hundred years，humans have begun destroying rainforests in search of three major resources(资源)：land for crops，wood for paper and other products，land for raising farm animals．This action affects the environment as a whole．For example，a lot of carbon dioxide (二氧化碳)in the air comes from burning the rainforests．People obviously have a need for the resources we gain from cutting trees but we will suffer much more than we will benefit.There are two main reasons for this．Firstly，when people cut down trees，generally they can only use the land for a year or two．Secondly，cutting large sections of rainforests may provide a good supply of wood right now，but in the long run it actually reduces the world’s wood supply．Rainforests are often called the world’s drug store．More than 25％ of the medicines we use today come from plants in rainforests．However，fewer than l％of rainforest plants have been examined for their medical value．It is extremely likely that our best chance to cure diseases lies somewhere in the world’s shrinking rainforests．72．Rainforests can help to adjust the climate because they ．A．reflect more heat into the atmosphereB．bring about high rainfall throughout the worldC．rarely cause the temperature to drop lower than l6℃D．reduce the effect of heat from the sun on the earth
Prehistoric men and women enjoyed a more varied diet(饮食)than people do now, since they ate species(种类)of plant and several hundred thousand types of living things. But only a tiny percentage of these were ever domesticated(驯化). Modern shops have hastened a trend towards specialization which began in the earliest days of agriculture. The food of rich countries has become cheaper relative to wages. It is speedily distributed in supermarkets, but the choice annually becomes less and less great. Even individual foods themselves become more standardized. We live in the world of the carrot specially blunted in order to avoid making a hole in the bag, and the tomato grown to meet a demand for a standard weight of eighteen tomatoes to a kilo. Siri von Reis Altschul asks: "Only the tree major cereals(谷物)and perhaps ten other widely cultivated species stand between famine and survival for the world's human population and a handful of drug plants has served Western civilization for several thousand years. A rather obvious question arises: are we missing something?" After all, there are 800,000 species of plant on earth.1. In prehistoric times people _____.A. ate much more than we do todayB. lived mainly on plant foodC. had a wide-ranging dietD. were more fussy about what they ate2. Most of us have come to expect _____.A. no variation in our dietB. a reduction in food suppliesC. a specialist dietD. food conforming to a set standard3. The specialization of food was started by _____.A. the emergence of supermarketsB. the rise of agricultureC. the rich countriesD. the modern shops4. According to the passage, people in the West today survive on _____.A. carrots and tomatoesB. several thousand types of plants and cerealsC. a very small number of cultivated foodsD. special species planted one thousand years age5. The conclusion seems to be that we _____.A. could make use of more natural speciesB. don't cultivate the right kind of foodC. produce more food than we needD. cultivate too many different species
If cloned animals could be used as organ donors, ().A、people don’t have to worry about cloning twins for transplantsB、raising animals such as pigs can help solve the problemC、the human body attacks and destroys tissue from other speciesD、it may be more efficient to produce such animals by cloning than by cur
Prehistoric men and women enjoyed a more varied diet than people do now, since they ate species of plant and several hundreds thousands types of living things. But only a tiny percentage of these were ever domesticated. Modern shops have hastened a trend towards specialization which began in the earliest days of agriculture. The food of the rich countries has become cheaper relative to wages. It is speedily distributed in supermarkets. But the choice annually becomes less and less great. Even individual foods themselves become more standardized. We live in the world of carrot specially blunted in order to avoid making a hole in the bag, and the tomato grown to meet a demand for a standard weight of weighting tomatoes to a kilo. Siri von Reis asks: "Only the three major cereals (谷物类食物) and perhaps ten other widely cultivated species stand between famine and survival for the world's human population and a handful of drug plants has served Western civilization for several thousand years. A rather obvious question arises: Are we missing something?" After all, there are 800 000 species of plant on earth.1、In prehistoric times people____.A、ate much more than we do todayB、lived mainly on plant foodC、had a wide-ranging dietD、were more fussy about what they ate2、Most of us have come to expect____.A、no variation in our dietB、a reduction in food suppliesC、a specialist dietD、food conforming to a set standard3、The specialization of food was started by____.A、the emergence of supermarketsB、the rise of agricultureC、the rich countriesD、the modern shops4、According to the passage, people in the West today survive on____.A、carrots and tomatoesB、several thousand types of plants and cerealsC、a very small number of cultivated foodsD、special species planted one thousand years ago5、The conclusion seems to be that we____.A、could make use of more natural speciesB、don't cultivate the right kind of foodC、produce more food than we needD、cultivate too many different species
This may have preserved the elephant from extinction as well as other animals () in Africa. A、huntedB、huntingC、that huntedD、are hunted
共用题干Why India Needs Its Dying VulturesThe vultures（秃鹰）in question may look ugly and threatening , but the sudden sharp decline in three species of India'S vultures is producing alarm rather than celebration,and it presents the world with a new kind of environmental problem.The dramatic__________(51)in vulture numbers is causing widespread disruption to people living in the__________(52)areas as the birds.It is also causing serious public health problems__________(53)the Indian sub-continent.While their reputation and appearance may be unpleasant to many Indians,vultures have___________(54) played a very important role in keeping towns and villages all over India___________(55).It is because they feed on dead cows.In India,cows are sacred animals and are___________(56) left in the open when they die in thousands upon thousands every year.The disappearance of the vultures has___________(57)an explosion in the numbers of wild dogs feeding on the remains of these___________(58)animals. There are fears that rabies（狂犬症）may increase as a result. And this terrifying disease may ultimately（最终）affect humans in the region,___________(59)wilddogs are its main carriers.Rabies could also spread to other animal species, __________(60)an even greater problem in the future.The need for action is___________(61),so an emergency project has been launched to find a solution to this serious vulture problem?Scientists are trying to___________(62)the disease causing the birds' deaths and,if possible,develop a cure.Large-scale vulture___________(63)were first noticed at the end of the l980s in India. A population survey at that time showed that the three species of vultures had declined___________(64)over 90 percent. All three species are now listed as"critically endangered".As most vultures lay only single eggs and ___________(65)about five years to reach maturity,reversing their population decline will be a long and dif- ficult exercise._________(63)A:deathsB:injuriesC:arnvalsD:attacks
共用题干第三篇Longer Lives for Wild ElephantsMost people think of zoos as safe places for animals,where struggles such as having difficulty finding food and avoiding predators（猛兽）don't exist. Without such problems,animals in zoos should live to a ripe （成熟的）old age.But that may not be true for the largest land animals on Earth.Scientists have known that elephants in zoos often suffer from poor health.Sometimes,they even become unable to have babies.To learn more about how captivity（圈养）affects elephants, a team of international scientists compared the life spans of female elephants born in zoos with female elephants living outdoors in their native lands. Zoos keep detailed records of all the animals in their care,documenting factors such as birth dates,illnes-ses,weight and death.These records made it possible for the researchers to analyze 40 years of data on 800 African and Asian elephants in zoos across Europe.The scientists compared the life spans of the zoo-born fe-male elephants with the life spans of thousands of wild female elephants in Africa and Asian elephants that work in logging camps（伐木场）, over approximately the same time period.The team found that female African elephants born in zoos lived an average of 16.9 years. Their wild counterparts who died of natural causes lived an average of 56 years一more than three times as long. Female Asian elephants followed a similar pattern. In zoos,they lived 18.9 years,while those in the logging camps lived 41.7 years.Scientists don't know yet why wild elephants seem to get on so much better than their zoo-raised coun-terparts.Georgia Mason,a biologist at the University of Guelph in Canada who led the study,thinks stress and obesity（肥胖症）may be to blame. Zoo elephants don't get the same kind of exercise they would in the wild,and most are very fat. Social lives of elephants are also much different in zoos than in the wild,where they live in large herds and family groups.The study raises some questions about acquiring more elephants to keep in zoos.While some threatened and endangered species living in zoos reproduce（生殖）successfully and maintain healthy populations,that doesn't appear to be the case with elephants.It can be inferred from the last paragraph that______________.A:zoo-born elephants should be looked after more carefullyB:zoos should keep more animals except elephantsC:it may not be wise to keep elephants in zoosD:elephants are no longer an endangered species
共用题干Why India Needs Its Dying VulturesThe vultures（秃鹰）in question may look ugly and threatening , but the sudden sharp decline in three species of India'S vultures is producing alarm rather than celebration,and it presents the world with a new kind of environmental problem.The dramatic__________(51)in vulture numbers is causing widespread disruption to people living in the__________(52)areas as the birds.It is also causing serious public health problems__________(53)the Indian sub-continent.While their reputation and appearance may be unpleasant to many Indians,vultures have___________(54) played a very important role in keeping towns and villages all over India___________(55).It is because they feed on dead cows.In India,cows are sacred animals and are___________(56) left in the open when they die in thousands upon thousands every year.The disappearance of the vultures has___________(57)an explosion in the numbers of wild dogs feeding on the remains of these___________(58)animals. There are fears that rabies（狂犬症）may increase as a result. And this terrifying disease may ultimately（最终）affect humans in the region,___________(59)wilddogs are its main carriers.Rabies could also spread to other animal species, __________(60)an even greater problem in the future.The need for action is___________(61),so an emergency project has been launched to find a solution to this serious vulture problem?Scientists are trying to___________(62)the disease causing the birds' deaths and,if possible,develop a cure.Large-scale vulture___________(63)were first noticed at the end of the l980s in India. A population survey at that time showed that the three species of vultures had declined___________(64)over 90 percent. All three species are now listed as"critically endangered".As most vultures lay only single eggs and ___________(65)about five years to reach maturity,reversing their population decline will be a long and dif- ficult exercise._________(57)A:ledtoB:acted asC:come fromD:slowed down
共用题干Chimpanzees1 Chimpanzees（黑猩猩）will soon be extinct（灭绝）.If the present rate of hunting and habitat（栖息地）destruction continues, then within 20 years, there will be no chimpanzees living in the wild. But this is more than an environmental or moral tragedy（悲剧）.Chimpan-zee extinction may also have profound implications（含意）for the survival of their distant relatives一human beings.2 In 1975 the biologist Marie-Claire King and Allan Wilson discovered that the human and chimpanzee genomes（基因组）match by ovet 98%. Compare this to the mouse, used as model for human disease in lab tests,which shares only 60% of its DNA with us.In fact, chimpanzees are far more similar to humans than they are to any other species of monkey. As well as resembling us genetically,chimps are highly intelligent and able to use tools.These facts alone should be enough to make protection of chimps an urgent priority（优先）.But there is another,more selfish reason to preserve the chimp.3 The chimpanzees' trump card（王牌）comes in the field of medical research. Chimpanzees are so similar to humans that veterinarians（兽医）often refer to human medical text-books when treating them. Yet chimpanzees do show differences in several key areas.In parti-cular,chimps are much more resistant to a number of major diseases.It is this ability that is so interesting.4 For example,chimps seem to show a much higher resistance than humans to HIV,the virus that causes AIDS. Indeed,their use as experimental animals in AIDS research has de-dlined because they are so resistant.5 By sequencing the chimp genome and pinpointing（找到）the place where the chimpanzee DNA sequence differs from that of humans,scientists hope to be able to discover which part of the genetic code gives chimps their increased resistance to some diseases. This,they hope,will allow them to develop new and more effective treatments for the human forms of these diseases. Such treatments could include the production of new drugs or even the alteration（改变）of the human genetic sequence. The recently completed human genome sequencing project has shown that such an effort is now well within our reach.The discovery of the genetic code of chimps will be helpful to______.A: some human disease treatmentsB: some diseasesC: human survivalD: human genomesE: key areasF: healthier lifestyle
共用题干Chimpanzees1 Chimpanzees（黑猩猩）will soon be extinct（灭绝）.If the present rate of hunting and habitat（栖息地）destruction continues, then within 20 years, there will be no chimpanzees living in the wild. But this is more than an environmental or moral tragedy（悲剧）.Chimpan-zee extinction may also have profound implications（含意）for the survival of their distant relatives一human beings.2 In 1975 the biologist Marie-Claire King and Allan Wilson discovered that the human and chimpanzee genomes（基因组）match by ovet 98%. Compare this to the mouse, used as model for human disease in lab tests,which shares only 60% of its DNA with us.In fact, chimpanzees are far more similar to humans than they are to any other species of monkey. As well as resembling us genetically,chimps are highly intelligent and able to use tools.These facts alone should be enough to make protection of chimps an urgent priority（优先）.But there is another,more selfish reason to preserve the chimp.3 The chimpanzees' trump card（王牌）comes in the field of medical research. Chimpanzees are so similar to humans that veterinarians（兽医）often refer to human medical text-books when treating them. Yet chimpanzees do show differences in several key areas.In parti-cular,chimps are much more resistant to a number of major diseases.It is this ability that is so interesting.4 For example,chimps seem to show a much higher resistance than humans to HIV,the virus that causes AIDS. Indeed,their use as experimental animals in AIDS research has de-dlined because they are so resistant.5 By sequencing the chimp genome and pinpointing（找到）the place where the chimpanzee DNA sequence differs from that of humans,scientists hope to be able to discover which part of the genetic code gives chimps their increased resistance to some diseases. This,they hope,will allow them to develop new and more effective treatments for the human forms of these diseases. Such treatments could include the production of new drugs or even the alteration（改变）of the human genetic sequence. The recently completed human genome sequencing project has shown that such an effort is now well within our reach.Paragraph 4______A: Reasons for HIV ResistanceB: Implications of Chimpanzee Extinction for HumansC: Effective AIDS TreatmentD: Genetic Similarities Between Chimps and HumansE: Chimps'Resistance to HIVF: Genetic Differences Between Chimps and Humans
共用题干Chimpanzees1 Chimpanzees（黑猩猩）will soon be extinct（灭绝）.If the present rate of hunting and habitat（栖息地）destruction continues, then within 20 years, there will be no chimpanzees living in the wild. But this is more than an environmental or moral tragedy（悲剧）.Chimpan-zee extinction may also have profound implications（含意）for the survival of their distant relatives一human beings.2 In 1975 the biologist Marie-Claire King and Allan Wilson discovered that the human and chimpanzee genomes（基因组）match by ovet 98%. Compare this to the mouse, used as model for human disease in lab tests,which shares only 60% of its DNA with us.In fact, chimpanzees are far more similar to humans than they are to any other species of monkey. As well as resembling us genetically,chimps are highly intelligent and able to use tools.These facts alone should be enough to make protection of chimps an urgent priority（优先）.But there is another,more selfish reason to preserve the chimp.3 The chimpanzees' trump card（王牌）comes in the field of medical research. Chimpanzees are so similar to humans that veterinarians（兽医）often refer to human medical text-books when treating them. Yet chimpanzees do show differences in several key areas.In parti-cular,chimps are much more resistant to a number of major diseases.It is this ability that is so interesting.4 For example,chimps seem to show a much higher resistance than humans to HIV,the virus that causes AIDS. Indeed,their use as experimental animals in AIDS research has de-dlined because they are so resistant.5 By sequencing the chimp genome and pinpointing（找到）the place where the chimpanzee DNA sequence differs from that of humans,scientists hope to be able to discover which part of the genetic code gives chimps their increased resistance to some diseases. This,they hope,will allow them to develop new and more effective treatments for the human forms of these diseases. Such treatments could include the production of new drugs or even the alteration（改变）of the human genetic sequence. The recently completed human genome sequencing project has shown that such an effort is now well within our reach.Scientists suspect that genes play a significant role in protecting chimps from getting______.A: some human disease treatmentsB: some diseasesC: human survivalD: human genomesE: key areasF: healthier lifestyle
共用题干Chimpanzees1 Chimpanzees（黑猩猩）will soon be extinct（灭绝）.If the present rate of hunting and habitat（栖息地）destruction continues, then within 20 years, there will be no chimpanzees living in the wild. But this is more than an environmental or moral tragedy（悲剧）.Chimpan-zee extinction may also have profound implications（含意）for the survival of their distant relatives一human beings.2 In 1975 the biologist Marie-Claire King and Allan Wilson discovered that the human and chimpanzee genomes（基因组）match by ovet 98%. Compare this to the mouse, used as model for human disease in lab tests,which shares only 60% of its DNA with us.In fact, chimpanzees are far more similar to humans than they are to any other species of monkey. As well as resembling us genetically,chimps are highly intelligent and able to use tools.These facts alone should be enough to make protection of chimps an urgent priority（优先）.But there is another,more selfish reason to preserve the chimp.3 The chimpanzees' trump card（王牌）comes in the field of medical research. Chimpanzees are so similar to humans that veterinarians（兽医）often refer to human medical text-books when treating them. Yet chimpanzees do show differences in several key areas.In parti-cular,chimps are much more resistant to a number of major diseases.It is this ability that is so interesting.4 For example,chimps seem to show a much higher resistance than humans to HIV,the virus that causes AIDS. Indeed,their use as experimental animals in AIDS research has de-dlined because they are so resistant.5 By sequencing the chimp genome and pinpointing（找到）the place where the chimpanzee DNA sequence differs from that of humans,scientists hope to be able to discover which part of the genetic code gives chimps their increased resistance to some diseases. This,they hope,will allow them to develop new and more effective treatments for the human forms of these diseases. Such treatments could include the production of new drugs or even the alteration（改变）of the human genetic sequence. The recently completed human genome sequencing project has shown that such an effort is now well within our reach.There is a difference of. less than 2% between the chimp and______.A: some human disease treatmentsB: some diseasesC: human survivalD: human genomesE: key areasF: healthier lifestyle
共用题干Chimpanzees1 Chimpanzees（黑猩猩）will soon be extinct（灭绝）.If the present rate of hunting and habitat（栖息地）destruction continues, then within 20 years, there will be no chimpanzees living in the wild. But this is more than an environmental or moral tragedy（悲剧）.Chimpan-zee extinction may also have profound implications（含意）for the survival of their distant relatives一human beings.2 In 1975 the biologist Marie-Claire King and Allan Wilson discovered that the human and chimpanzee genomes（基因组）match by ovet 98%. Compare this to the mouse, used as model for human disease in lab tests,which shares only 60% of its DNA with us.In fact, chimpanzees are far more similar to humans than they are to any other species of monkey. As well as resembling us genetically,chimps are highly intelligent and able to use tools.These facts alone should be enough to make protection of chimps an urgent priority（优先）.But there is another,more selfish reason to preserve the chimp.3 The chimpanzees' trump card（王牌）comes in the field of medical research. Chimpanzees are so similar to humans that veterinarians（兽医）often refer to human medical text-books when treating them. Yet chimpanzees do show differences in several key areas.In parti-cular,chimps are much more resistant to a number of major diseases.It is this ability that is so interesting.4 For example,chimps seem to show a much higher resistance than humans to HIV,the virus that causes AIDS. Indeed,their use as experimental animals in AIDS research has de-dlined because they are so resistant.5 By sequencing the chimp genome and pinpointing（找到）the place where the chimpanzee DNA sequence differs from that of humans,scientists hope to be able to discover which part of the genetic code gives chimps their increased resistance to some diseases. This,they hope,will allow them to develop new and more effective treatments for the human forms of these diseases. Such treatments could include the production of new drugs or even the alteration（改变）of the human genetic sequence. The recently completed human genome sequencing project has shown that such an effort is now well within our reach.Chimpanzee extinction may affect______.A: some human disease treatmentsB: some diseasesC: human survivalD: human genomesE: key areasF: healthier lifestyle
Every year gray whales migrate from the Bering Sea in Alaska to the Baja Peninsula in Mexico.Eleven gray whales have died in the San Francisco Bay in the last three weeks．No one knows why the whales are dying.Last year 270 whales died along the whales'migration route．Many people think starvation is the cause．This year the dead whales seem to have more blubber(fat)on them.Twenty years ago,the gray whale was listed as an endangered species.Some scientists think that the larger number of whales makes it hard to find enough food．More whales create more pressure on the food supply,a supply that some scientists say may have dwindled as a result of the warm waters of El Nino.Most of the whales have been dead for many days before they are found and studied．This makes it hard to find the reason for death.65 whales have been seen in the San Francisco Bay Area this year compared to 17 last year．The whales could be dying from many diseases,but it may be over-population．One reason it is difficult to know why the whales are dying is that__.A.the whales travel such a long distanceB.there are more whales than there used to beC.the whale bodies are too old to study by the time they are foundD.the whales are endangered
Text 2 When people talk about a"north-south divide"in Britain they are usually referring to house prices,employment and the ratio of private-sector to public-sector jobs.The south scores higher on all such measures.But new data from the British Trust for Ornithology（BTO）,a research charity,hints at the growth of another north-south divide-this time to the north's benefit.Every 20 years the BTO produces a superbly detailed atlas of bird life in Britain and Ireland.The 2007 t0 2011 edition is cheery:more species are tallied than in previous atlases,and many birds are increasing in number.Compared with two decades ago,45%of regular native species are ranging more widely while 32%are living in smaller areas;the rest have stayed put.But the most striking news comes from the north.The overall populations of woodland,farmland and migrant perching birds are up in northern England and Scotland but down in the south.The same is true of individual species such as the garden warbler,bullfinch and swallow.The number of cuckoos,a closely-watched species,declined by 63%in England between 1995 and 2010 but by only 5%in Scotland.Raptors are faring especially well in the south,but their numbers are rising in most parts of Britain.Partly this reflects climate change,suggests Simon Gillings of the BTO.Some birds are drawn to warmer winters in Scotland and northem England;visiting migrants may stick around for longer.Hard though it may be to believe during a week of torrential rain,the south is becoming drier,pushing snipe northward.More efficient farming has squeezed some farmland species.Some birds find it harder to make homes in the south,too.Pressure on housing means dilapidated buildings and barns,handy for nesting,have been converted into human dwellings.Between 2006 and 2012 the number of vacant dwellings fell by 17%in London and by 12%in Kent.Over the same period the number of empty houses increased by 16%in Derbyshire and by 10%in Lancashire:Northern mining villages once full of workers are now sparsely populated,points out Ian Bartlett,a birdwatcher in Hartlepool,in north-east England.They have become hot spots for birds and the people who watch them.Culrural difference also plays a part,thinks Mark Cocker,an expert on birds.The"obsession with tidiness"is stronger in the south,he says.Fewer people cultivate gardens;they prefer to cover them in decking and remove weeds from between concrete slabs.Village greens are mowed short.In contrast,Scotland and northern England have more trees,grassland and wind-swept moors.Less popular with humans,rugged parts of the countryside are filling up with a winged population instead.According to the passage,what is"north-south divide"recently?A.Home prices.B.Job hunting.C.Species richness.D.Benefit plan.
Text 2 When people talk about a"north-south divide"in Britain they are usually referring to house prices,employment and the ratio of private-sector to public-sector jobs.The south scores higher on all such measures.But new data from the British Trust for Ornithology（BTO）,a research charity,hints at the growth of another north-south divide-this time to the north's benefit.Every 20 years the BTO produces a superbly detailed atlas of bird life in Britain and Ireland.The 2007 t0 2011 edition is cheery:more species are tallied than in previous atlases,and many birds are increasing in number.Compared with two decades ago,45%of regular native species are ranging more widely while 32%are living in smaller areas;the rest have stayed put.But the most striking news comes from the north.The overall populations of woodland,farmland and migrant perching birds are up in northern England and Scotland but down in the south.The same is true of individual species such as the garden warbler,bullfinch and swallow.The number of cuckoos,a closely-watched species,declined by 63%in England between 1995 and 2010 but by only 5%in Scotland.Raptors are faring especially well in the south,but their numbers are rising in most parts of Britain.Partly this reflects climate change,suggests Simon Gillings of the BTO.Some birds are drawn to warmer winters in Scotland and northem England;visiting migrants may stick around for longer.Hard though it may be to believe during a week of torrential rain,the south is becoming drier,pushing snipe northward.More efficient farming has squeezed some farmland species.Some birds find it harder to make homes in the south,too.Pressure on housing means dilapidated buildings and barns,handy for nesting,have been converted into human dwellings.Between 2006 and 2012 the number of vacant dwellings fell by 17%in London and by 12%in Kent.Over the same period the number of empty houses increased by 16%in Derbyshire and by 10%in Lancashire:Northern mining villages once full of workers are now sparsely populated,points out Ian Bartlett,a birdwatcher in Hartlepool,in north-east England.They have become hot spots for birds and the people who watch them.Culrural difference also plays a part,thinks Mark Cocker,an expert on birds.The"obsession with tidiness"is stronger in the south,he says.Fewer people cultivate gardens;they prefer to cover them in decking and remove weeds from between concrete slabs.Village greens are mowed short.In contrast,Scotland and northern England have more trees,grassland and wind-swept moors.Less popular with humans,rugged parts of the countryside are filling up with a winged population instead.According to the text,more species are found in the north Britain,because____A.climate change plays a major roleB.some birds enjoy making home in the forestC.there is little space for birds in the southD.many distinctive birds are killed in the south
单选题The skulls and pelvic bones of some species of dinosaur share characteristics with the skulls and pelvic bones of all modern birds. Even though not all dinosaurs have these characteristics, there are scientists who claim that all animals that do have these characteristics are dinosaurs. If the statements above and the claim of the scientists are true, which of the following must also be true?ABirds share more characteristics with dinosaurs than they do with other animals.BSome ancient dinosaurs were indistinguishable from modern birds.CAll animals whose skulls share the characteristics of those of modern birds also have pelvic bones that are similar to those of modern birds.DModern birds are dinosaurs.EAll dinosaurs are birds.
单选题Some paleontologists claim that the discovery of what appear to be feathers in the fossil of an Archosaur could force a revision of current theories on the phylogeny of Archosaurs, alter conceptions of dinosaur skin surfaces, and require scholars to credit birds with a far earlier orion than previously thought.Arequire scholars to credit birds with a far earlier origin than previously thoughtBscholars may be required to credit birds with a far earlier origin than previously thoughtCrequire a crediting by scholars of birds with a far earlier origin than previously thoughtDcompared to what was previously thought, require scholars to credit birds with a far earlier originEcrediting birds with a far earlier origin than scholars had previously though
问答题This section consists of one passage followed by a summary. Read the passage carefully and complete the summary below by choosing no more than three words from the passage for each blank. Remember to write the answers on the answer sheet. Questions 1 to 5 are based on the following passage. The giant panda, the creature that has become a symbol of conservation, is facing extinction. The major reason is loss of habitat, which has continued despite the establishment, since 1963, of 14 panda reserves. Deforestation, mainly carried out by farmers clearing land to make way for fields as they move higher into the mountains, has drastically contracted the mammal’s range. The panda has disappeared from much of central and eastern China, and is now restricted to the eastern flank of the Himalayas in Sichuan and Gansu provinces, and the Qinling Mountains in Shanxi province. Fewer than 1, 400 of the animals are believed to remain in the wild. Satellite imagery has shown the seriousness of the situation; almost half of the panda’s habitat has been destroyed or degraded since 1975. Worse, the surviving panda population has also become fragmented; a combination of satellite imagery and ground surveys reveals panda “islands” in patches of forest separated by cleared land. The population of these islands, ranging from fewer than ten to more than 50 pandas, has become isolated because the animals are unwilling to cross open areas. Just putting a road through a panda habitat may be enough to split a population in two. The minuscule size of the panda populations worries conservationists. The smallest groups have too few animals to be viable, and will inevitably die out. The larger populations may be viable in the short term, but will be susceptible to genetic defects as a result of inbreeding.In these circumstances, a more traditional threat to pandas—the cycle of flowering and subsequent withering of the bamboo that is their staple food—can become literally species—threatening. The flowerings prompt pandas to move from one area to another, thus preventing inbreeding in what would otherwise be sedentary populations. In panda islands, however, bamboo flowering could prove catastrophic because the pandas are unable to emigrate. The latest conservation management plan for the panda, prepared by China’s Ministry of Forestry and the World Wide Fund for Nature, aims primarily to maintain panda habitats and to ensure that populations are linked wherever possible. The plan will change some existing reserve boundaries, establish 14 new reserves and protect or replant corridors of forest between panda islands. Other measures include：better control of poaching, which remains a problem despite strict laws, as panda skins fetch high prices; reducing the degradation of habitats outside reserves; and reforestation. The plan is ambitious. Implementation will be expensive—56.6 million yuan(US $12.5 million)will be needed for the development of the panda reserves—and will require participation by individuals ranging from villagers to government officials.Summary The survival of the giant panda is being seriously threatened. Panda numbers have already seriously decreased. This is largely because the overall size of their 1 has been reduced, and habitable areas are now disconnected from each other. Two results are that pandas are more prone to 2 problems and are unable to move around freely to follow the growth cycles of the bamboo that they eat. A new plan aims to 3 existing panda habitats and to join many of them together. This plan also includes reforestation and the creation of 4 To succeed ,everyone ,including both the government and 5 will have to cooperate.
单选题The speaker of the passage is of the opinion that ______.Aprotecting the farmland is more important than protecting wild animalBprotecting endangered species is more important than protecting the interests of the farmersCprotecting the farmland and the wild animals are equally importantDone can rely more on bees than mice to frighten beasts off the farm
单选题It can be concluded from the passage that ______.Alarge families may be considered as a heavy burden by the rural poorBthe actions of national and international power brokers have an important effect upon the decision made by the rural poorCthe actions of those with the highest fertility, the rural poor, ultimately determine the rate of population growthDhaving large families had more advantages than disadvantages in those poor areas
单选题Which of the following is an appropriate title for this passage?APoor Sleep May Lead to Too Much Stored Fat and DiseaseBSleep Experts Had Exciting Findings in a Fat StudyCAmericans Should Have More Than Six Hours of SleepDBad Things Happen if Fat Cells Become Our Friend
问答题Practice 2 Until recently, scientists knew little about life in the deep sea, nor had they reason to believe that it was being threatened. Now, with the benefit of technology that allows for deeper exploration, researchers have uncovered a remarkable array of species inhabiting the ocean floor at depths of more than 660 feet, or about 200 meters. At the same time, however, technology has also enabled fishermen to reach far deeper than ever before, into areas where bottom trawls can destroy in minutes what has taken nature hundreds and in some cases thousands of years to build. Many of the world's coral species, for example, are found at depths of more than 200 meters. It is also estimated that roughly half of the world's highest seamounts - areas that rise from the ocean floor and are particularly rich in marine life - are also found in the deep ocean. These deep sea ecosystems provide shelter, spawning and breeding areas for fish and other creatures, as well as protection from strong currents and predators. Moreover, they are believed to harbor some of the most extensive reservoirs of life on earth, with estimates ranging from 500,000 to 100 million species inhabiting these largely unexplored and highly fragile ecosystems.
问答题The Truth about Genetically Modified Food At almost every public lecture I give, someone asks me my opinion on genetic modification—whatever be the topic of the lecture. Genetic modification (GM) has the power to save lives through its use in medicine, such as the production of insulin for diabetics or the treatment of genetic disorders. The current outcry comes when it is used to produce food. Some of these public concerns reflect real problems, but others are fuelled by misinformation and overdramatisation. There is nothing new about crop modification; plant breeders have been doing it since agriculture began. The wonderful range of apples or potatoes we now enjoy is the result of crossing different varieties. Cabbages, Brussels sprouts, cauliflower, kohlrabi, kale and broccoli all originated from one botanical species. Modern molecular biology has enabled us to go much further. We can now isolate the gene for a particular characteristic of an organism and transfer it to another species. It is this practice of transforming a plant with alien genes—perhaps from an animal or bacterium—that is causing all the controversy. There are three main concerns. Scientists can now take a gene for resistance to a particular herbicide and transfer it to a crop: when these plants are sprayed with weed-killer, the weeds are destroyed while the crop is unharmed. A prime concern is the harmful effect this could have on the biodiversity of farmland, where so many insects, birds and other animals depend upon “weed” species. Another fear is that alien genes from a GM plant could escape into a wild population of a related species. Since plants are fertilized by pollen that is carried through their, often for great distances, this is entirely possible. A wild species modified in this way with pesticide resistance could become a “super-weed”, while a species that becomes unnaturally resistant to animals that feed on it could disrupt the food chain. The third worry concerns a proposal to produce seeds for cereals that cannot germinate to produce next year’s seeds. This “terminator technology” would be of obvious advantage to seed companies, since farms would be forced to buy new weed annually. But the same technology could be devastating to some farmers in the developing world who depend upon saving some seeds for next year’s crop. Fortunately this technology is not yet in use and there has been strong pressure to abandon it. I would not hesitate to eat a GM vegetable—it is most unlikely that the current modifications are harmful to the consumer, despite what we read in the press. However, the introduction of animal genes into food plants presents considerable ethical difficulties to vegetarinsarians and member of religious that forbid the eating of certain animals. This is one of the reasons people are demanding that tall genetically modified food products be clearly labeled. The public have a fight to know what they are eating and a fight to choose. I believe that in my own nation GM is well regulated, but this cannot be said for some other countries. One of the problems is that at the moment this technology is commercially motivated. Because the compositions developing GM food want to introduce it as quickly as possible, in my opinion, it is being rushed into without adequate research or precautions. Genetic’ modification is here to stay, and there is no doubt it will save lives. But ,like so many other scientific discoveries, such as splitting the atom, it can be seriously misused. Instead of condemning the technique, we, should ensure it is used wisely. We need to evaluate each application carefully, from environmental and ethical standpoints, and we must urge governments and companies to use it for good rather than for greed.
单选题It may be concluded from this passage that _____.AIslamic artists have had to create architectural decoration with images of flowers or geometric formsBhistory teachers are more objective than artistsCit is more difficult to study art history than general historyDpeople and stories from the Bible were painted on churches and other Buildings in order to popularize the Bible