题目内容
Dr.Peter Spence，________ headmaster of the school，told us，“________ fifth of pupils here go on to study at Oxford and Cambridge.”????????????? ????????????? ????????????? ????????????? ????????????? ????????????? ????????????? (2011·四川，18)
A．/；A? B．/；The
C．the；The? D．a；A
A
【解析】
句意为：彼得·斯宾塞博士，即学校的校长告诉我们：“这里五分之一的学生会继续在牛津和剑桥大学学习。”Dr.Peter Spence与其后的headmaster of the school是同位关系，表示官职的名词前应使用零冠词。要表示分数五分之一，其分子可用冠词a或one。
期末宝典单元检测分类复习卷系列答案One genetic mutation(基因突变)occurs on average for every 15 cigarettes that a typical lung-cancer patient smokes, according to a study that has found for the first time all of the mutations happen during the lifetime of a cancer patient.
Scientists have completed a full genetic examinations of the genomes（基因组） of cancer patients, and hope the information will lead to a basic understanding of the causes of cancer—and possibly drugs and treatments—by making out the mutations that turn a healthy cell into a cancerous tumor cell.
They studied a lung-cancer patient who had about 23,000 DNA mutations in his lung cells that were connected with exposure(暴露) to the toxins found in cigarette smoke and had built up over his lifetime.
They also looked at a patient with malignant melanoma(恶性黑色肿瘤), the most dangerous form of skin cancer, who had got 30,000 special mutations known to be connected with exposure to sunlight.
Scientists believe this new finding into the genetics of cancer will finally lead to new drugs and perfect treatments that aim at the specific changes to the gene that cause the
disease, as well as new techniques for discovering following cancers that have escaped from treatment in other parts of the body.
“For the first time, we have a complete map of all mutations in a cancer cell,” said Dr. Peter Campbell, who led the Cancer Genome project to work out the whole DNA system of tumor cells in order find the mutations.
A similar method was performed on the cells of a patient with skin cancer, which is how the researchers were able to show that the malignant skin cells contained changes that resulted from exposure to light.
“These are the two main cancers in the developed world for which we know the chief exposure. For lung cancer it is cigarette smoke, and for malignant melanoma it is exposure to sunlight,” Professor Campbell said.
【小题1】What can the genetic examination of the genomes of cancer patients be used for?
| A．To help the professors to win the Nobel Prizes. |
| B．To advance the study of reason and cure of cancer. |
| C．To make the medicine industries earn more money. |
| D．To help the cancer patients reduce their pain. |
| A．smoke | B．sunlight | C．cell | D．poison |
| A．The lung-cancer patient had 30,000 mutations in his lung cells. |
| B．The genetics of cancer will finally lead to new drugs soon. |
| C．It’s the first time that people mapped mutations in a cancer cell. |
| D．Dr. Peter tries to invent a new drug with the DNA system. |
| A．Their smoking too much in daily life. |
| B．Their receiving too much sunshine. |
| C．Their refusing to accept treatment. |
| D．Their interest in travelling abroad. |
Researchers at Sweden’s KTH Royal Institute of Technology say they have found further proof that the wolf ancestors of today’s dogs can be from southern East Asia -- findings that are contrary to theories placing the birth place in the Middle East. Dr Peter Savolainen, KTH researcher in evolutionary genetics, says a new study released Nov. 23 confirms that an Asian region south of the Yangtze River was the principal and probably the only region where wolves were domesticated（驯化）by humans.
Research data show clearly that dogs are descended from wolves, but there’s never been scientific agreement on where in the world the domestication process began. “Our analysis of Y-chromosomal（染色体）DNA now confirms that wolves were first domesticated in Asia south of Yangtze River -- we call it the ASY region -- in southern China or Southeast Asia,” Savolainen says.
The Y data supports previous evidence from mitochondrial（线粒体）DNA. “Taken together, the two studies provide very strong evidence that dogs appeared first in the ASY region,” Savolainen says.
Archaeological data and a genetic study recently published in Nature suggest that dogs originate from the Middle East. But Savolainen rejects that view. “Because none of these studies included samples from the ASY region, evidence from ASY has been overlooked,” he says.
Peter Savolainen and PhD student Mattias Oskarsson worked with Chinese colleagues to analyse DNA from male dogs around the world. Their study was published in the scientific journal Heredity.
Approximately half of the gene pool was universally shared everywhere in the world, while only the ASY region had the entire range of genetic diversity. “This shows that gene pools in all other regions of the world most probably originate from the ASY region,” Savolainen says.
“Our results confirm that Asia south of the Yangtze River was the most important -- and probably the only -- region for wolf domestication, and that a large number of wolves were domesticated,” says Savolainen.
In separate research published recently in Ecology and Evolution, Savolainen, PhD student Arman Ardalan and Iranian and Turkish scientists conducted a comprehensive study of mitochondrial DNA, with a particular focus on the Middle East. Because mitochondrial DNA is inherited only from the mother in most species, it is especially useful in studying evolutionary relationships.
“Since other studies have indicated that wolves were domesticated in the Middle East, we wanted to be sure nothing had been missed. We find no signs whatsoever that dogs originated there,” says Savolainen.
In their studies, the researchers also found minor genetic contributions from crossbreeding between dogs and wolves in other geographic regions, including the Middle East.
“This subsequent dog/wolf hybridisation（混合淡化技术）contributed only modestly to the dog gene pool,” Savolainen explains.
【小题1】What does Dr. Peter Savolainen believe?
A. Dogs’ ancestors came from the Middle East.
B. Wolves were probably first trained to work for humans in the ASY region.
C. Analysis of Y-chromosomal DNA should be combined with mitochondrial DNA.
D. Samples of the previous studies are enough to support the conclusion.
【小题2】We can learn from the passage that _______.
| A．there is a universal agreement on the place of first domestication |
| B．data from ASY may highlight where dogs came from |
| C．Dr. Savolainen’s research mainly focuses on the Middle East |
| D．the dog/wolf hybridization makes up most of the dog gene pool |
| A．It is only used in studying evolutionary relationships. |
| B．It alone can provide hard evidence for Savolainen’s research. |
| C．It is the most useful in finding out the birth place of dogs. |
| D．It comes from the mother of most animals and plants. |