1、考研英语（阅读）模拟试卷 158 及答案与解析Part ADirections: Read the following four texts. Answer the questions below each text by choosing A, B, C or D. (40 points)0 AThe work builds on a study published last year by Shinya Yamanaka of Kyoto University in Japan, which showed that mouse tail cells could be transformed
2、 into ES-like cells by inserting four genes(Science Now, 3 July 2006). Those genes are normally switched off after embryonic cells differentiate into the various cell types. In June this year, Yamanaka and another group reported that the cells were truly pluripotent, meaning that they had the potent
3、ial to grow into any tissue in the body(Science Now, 6 June).BIn the new work, Yamanaka and his colleagues used a retrovirus to ferry into adult cells the same four genes they had previously used to reprogram mouse cells: OCT3/4, SOX2, KLF4, and c-MYC. They reprogrammed cells taken from the facial s
4、kin of a 36-year-old woman and from connective tissue from a 69-year-old man. Roughly one iPS cell line was produced for every 5,000 cells the researchers treated using the technique, an efficiency that enabled them to produce several cell lines from each experiment.CNow the race to repeat the feat
5、in human cells has ended in a tie: Two groups report today that they have reprogrammed human skin cells into so-called induced pluripotent cells(iPSs). In a paper published online in Cell, Yamanaka and his colleagues show that their mouse technique works with human cells as well. And in a paper publ
6、ished online in Science, James Thomson of the University of Wisconsin, Madison, and his colleagues report success in reprogramming human cells, again by inserting just four genes, two of which are different from those Yamanaka uses.DOnce the kinks are worked out, “the whole field is going to complet
7、ely change,“ says stem cell researcher Jose Cibelli of Michigan State University in East Lansing. “People working on ethics will have to find something new to worry about. “EThomsons team started from scratch, identifying its own list of 14 candidate reprogramming genes. Like Yamanakas group, the te
8、am used a systematic process of elimination to identify four factors: OCT3 and SOX2, as Yamanaka used, and two different genes, NANOG and LIN28. The group reprogrammed cells from fetal skin and from the foreskin of a newborn boy. The researchers were able to transform about one in 10,000 cells, less
9、 than Yamanakas technique achieved, Thomson says, but still enough to create several cell lines from a single experiment.FScientists have managed to reprogram human skin cells directly into cells that look and act like embryonic stem(ES)cells. The technique makes it possible to generate patient-spec
10、ific stem cells to study or treat disease without using embryos or oocytesand therefore could bypass the ethical debates that have plagued the field. “This is like an earthquake for both the science and politics of stem cell research,“ says Jesse Reynolds, policy analyst for the Center for Genetics
11、and Society in Oakland, California.GAlthough promising, both techniques share a downside. The retroviruses used to insert the genes could cause tumors in tissues grown from the cells. The crucial next step, everyone agrees, is to find a way to reprogram cells by switching on the genes rather than in
12、serting new copies. The field is moving quickly toward that goal, says stem cell researcher Douglas Melton of Harvard University. “ It is not hard to imagine a time when you could add small molecules that would tickle the same networks as these genes“ and produce reprogrammed cells without genetic a
13、lterations, he says.Order:5 ATime Away That Shapes CareersBFaculty Weigh inCAdmissions ImpactDNo RegretsEHelp Students Develop Strategies to MingleFFinding OpportunitiesGBuild Strong Sense of ResponsibilityData from the National Science Foundation indicate that over the last 25 years, there has been
14、 a fairly consistent 1- to 2-year time variance in the interval between an undergraduate degree and a Ph. D. So where does the extra time go?Part of it is the “postbac“ : recent graduates often take between the bachelors degree and graduate school. “Postbac“ time allows recent graduates to mature, g
15、ain some perspective, and learn new skills before starting out on a long graduate program. A short hiatus before the long road, students and faculty members say, is almost always good.【R1】 _Most faculty members agree that if students have a clear idea of what they want to study and what their goals
16、are, they can make a successful direct transition to graduate school. “For the great majority of students, some time off is a good idea,“ says Deborah Goldberg, a professor of ecology and evolutionary biology at the University of Michigan. Students with more life experience often have the maturity i
17、t takes to persevere through a Ph. D. , she says. She has observed that students without that experience are more likely to feel burned out and to drop out of their Ph. D. programs than are students who take time off.【R2】 _Faculty members agree that 1 to 2 years away does not hurt a student in the g
18、raduate-admissions process. But relevant workespecially research experienceoften has a better-than-neutral effect on admissions prospects. As he considered graduate programs, Gries was able to discuss his research in one-on-one interviews with faculty members, and all of them, he says, considered hi
19、s year of work an advantage. Maturity and life experience are the main selling points for “postbac“ time, but the details of what you learn can matter, too. In addition, many faculty members appreciate the perspectives students with added life experience bring to their classrooms and laboratories.【R
20、3】 _Individuals we spoke to who had completed a “postbac“ expressed no regrets about their decisions. Sarah Walker sees only advantages to the time that she spent in the Peace Corps and working in Africa. After she finished her undergraduate degree at Smith College in Northampton, Massachusetts, in
21、1994, she worked as a biology and mathematics teacher for 2 years in Lesotho. When she returned to graduate school at the University of Virginia, Charlottesville, in 1998, Walker found that her experience in the Peace Corps made teaching assignments easier. Her experience in Africa shaped her career
22、 goals: Her thesis research in environmental science examined the impact of land-use changes on ecological systems. Walker says her relationships with faculty members were also improved by her time away.【R4】 _Finding a postgraduate position outside of organized programs such as the Peace Corps requi
23、res undergraduates to mine a diverse network of resources. Talk to as many people as possible, Goldberg says; faculty members might know of colleagues who are looking for research assistants. Regional and national meetings present great chances for undergraduates to scout for positions.【R5】 _After c
24、ompleting the core requirements for her Ph. D. in 2005, Walker took a job at Winrock International, a nonprofit international development organization in Arlington, Virginia. Her job advising projects that help limit carbon emissions and deforestation in the developing world-builds on both her Peace
25、 Corps experience and scientific expertise. Unsurprisingly, shes a strong advocate of the postbac. “Taking 2 yearsoffhas zero negative impact on your ability to continue on in school,“ she advises. It allows you to grow as a person and have a better sense of what it is that you want to do.6 【R1 】7 【
26、R2 】8 【R3 】9 【R4 】10 【R5 】10 The time-enduring metaphor of the war on cancer, as overused as it may be, is as evocative as ever to describe our efforts to beat the disease that will claim nearly 566,000 American lives this year alone. So lets fall back on martial imagery to describe our current posi
27、tion: We now know the enemy far better than ever before. And that promises much more precise targets.【R1 】_ But mounting discoveries about the astoundingly complex essence of cancerthat its causes lie in multitudes of genes gone awryare also pointing the way toward treatments aimed in laser-like fas
28、hion at a patients unique set of genetic limitations. In mid-October, scientists reported in Nature that theyve identified 26 key mutated genes linked to lung cancer, for example.【R2 】_Yet until quite recently, the only tools availablethe blunt-force mainstays of surgery, chemotherapy, and radiation
29、treated everyone much the same. Then, in the 1990s, powerful new computing technology allowed researchers to begin comparing the DNA of cancerous and healthy tissues and gain a look at the very blueprints of similar-looking but markedly different tumors.【R3 】_It seems that many of the abnormal genes
30、 operate together to create trouble in a smaller number of distinct cellular pathwaysthe molecular processes that make a cancer cell so deadly. These common pathways are the likely drug targets. Think of it this way: Multiple cars are taking separate routes to the same garage, and instead of trying
31、to stop each car on the road, you block the driveway. The pathways are shared by cancers in different organs; the new lung cancer study, for example, revealed mutations also fingered in cancer of the retina and colon, among others, suggesting that drugs can be used against a panoply of tumors.【R4 】_
32、Theoretically, that means drugs could be much better matched to patients. That kind of matching is only occasionally available now. Lung cancer drugs Tarceva and Iressa target the cell-growth receptor EGFR; for reasons not yet fully understood but most likely involving mutations in EGFR, they work b
33、etter in some patients than in others.【R5 】_For one thing, finding all the mutations linked to a certain cancer isnt enough. How and why are genes turned on and off? And how do the signaling pathways affect and influence each other? Even when a target is identified as important and a drug made to bl
34、ock it, chances are the tumor has another way to reach the same endor will find one as it continues to grow and mutate, which explains why people develop resistance to targeted therapies that work at first.What this all suggests, many say, is that just as HIV is now managed by a drug cocktail, cance
35、r may one day be handled as a chronic disease controlled by a changing mix of several drugs at once in sequence or combination. The race is on to expand the arsenal. According to a recent Datamonitor report, 10 new targeted drugs have entered the marketplace since 2005, and researchers are studying
36、existing therapies to see if theyre more effective together.AIts been clear for years, for example, that cancers vary widely even if they look the same under a microscope: Some are slow growing, others are aggressive; some patients respond to one drug, while others are not helped at all.BDevising tr
37、eatments to combat every single mutation would be a huge taskbut that may not be necessary, experts say.COf course, as even Sun Tzu recognized, intel must be translated into effective action, and in this struggle, that effort has been all too plagued by failure.DWithin just a few years, the technolo
38、gy may be available to sequence an individual tumors genes and find out exactly what pathways need blocking, says Raymond DuBois, dean of M. D. Anderson Cancer Center in Houston and president of the American Association for Cancer Research.EA new study has found that mutations in either of two genes
39、 are involved in the development of lung cancer.FStudies have found that the epidermal growth factor receptor(EGFR)gene is mutated in many non-smallcell lung cancers and that these mutations are associated with increased sensitivity to gefitinib(Iressa)or erlotinib(Tarceva), tyrosine kinase(TK)inhib
40、itors that target EGFR.GClearly, converting this mass of new genetic information into perfectly tailored therapies isnt a quick and dirty exercise.11 【R1 】12 【R2 】13 【R3 】14 【R4 】15 【R5 】15 Im notorious among my friends for being an early-morning exerciseryou know, the annoying person who bounces ri
41、ght out of bed before the alarm goes off(I have never hit the snooze button in my life), jumps into her running shoes, and is out the door for a run, swim, or bike ride before Matt Lauer is into his first cup of coffee.【R1】_The trouble is, I usually end up putting them off until after work, and then
42、 until the next day, when the entire cycle repeats itself.【R2 】_But now that Im putting down the hammer and getting back into a workout routine, Im finding that it can be hard to motivate myself to actually, you know, work out. So I decided to check out whether technology offers any better answers t
43、han simply putting a Post-it on my computer.Using text messaging, phone messages, and E-mail to motivate people to better health behavior is a hot topic, it turns out. Researchers in Scotland, for example, are using a test-messaging system called Sweet Talk to remind teens with type 1 diabetes to ta
44、ke their insulin. Text messages have also been used to remind people to take their medications and help them quit smoking and have been studied to follow up with bulimia patients.【R3 】_Or send a delayed E-mail message to yourself, an option available in some E-mail programs, including Microsoft Outl
45、ook. Or use a Web-based service to remind yourself via text messages or E-mail; Google Calendar and OhDontForget. com both allow you to program in text messages to yourself.【R4 】_(Sweet Talk alone didnt improve blood sugar levels in the absence of intensive insulin therapy, while the bulimics studie
46、d found the automated messages were impersonal.)In that case, its a personal touch that may matter most. Researchers at Ohio State University Medical Center are studying postmenopausal women who are overweight and dont exercise, thus putting them at higher risk for breast cancer. Theyre giving each
47、woman a pedometer and a goal of working up to 10,000 steps a day. But one group of women in the 12-week study will get daily automated voice messages reminding them to work out, while the other will get both voice messages and calls from a real live persona coach. The hypothesis is that the ones who
48、 speak to a real person will better stick to their goals(and possibly prevent cancer).【R5 】_Tom Holland, a Darien, Conn-based exercise physiologist who coaches and trains people ranging from Ironman, triathletes to fitness newbies, says one of his clients is trying to lose weight as her main goal. “
49、I send her a little message every day when shes not expecting it,“ he says. “It may just say You can do it, but it really, really works. It shows that someone took time out and is thinking about them and is on their side. “Im experimenting with Google Calendar for the reminders. And for face-to-face motivation, Ive instructed my boyfriend to harass me to go running at least every other day, while hes told me to make sure he plays bask
