2019雅思阅读考试真题(15)

2019年雅思考试模考巩固试题及答案四

1. Washing， brushing and varnishing fossils — all

standard conservation treatments used by many fossil hunters

and museum curators alike — vastly reduces the chances of

recovering ancient DNA.

2. Instead， excavators should be handling at least some

of their bounty with gloves， and freezing samples as they

are found， dirt and all， concludes a paper in the

Proceedings of the National Academy of Sciences today.

3. Although many palaeontologists know anecdotally that

this is the best way to up the odds of extracting good DNA，

Eva-Maria Geigl of the Jacques Monod Institute in Paris，

France， and her colleagues have now shown just how important

conservation practices can be. This information， they say，

needs to be hammered home among the people who are actually

out in the field digging up bones.

4. Geigl and her colleagues looked at 3，200-year-old

fossil bones belonging to a single individual of an extinct

cattle species， called an aurochs. The fossils were dug up

at a site in France at two different times — either in 1947，

and stored in a museum collection， or in 2004， and

conserved in sterile conditions at -20 oC.

5. The team’s attempts to extract DNA from the 1947

bones all failed. The newly excavated fossils， however， all

yielded DNA.

6. Because the bones had been buried for the same amount

of time， and in the same conditions， the conservation

method had to be to blame says Geigl. “As much DNA was

degraded in these 57 years as in the 3，200 years before，”

she says.

Wash in， wash out

7. Because many palaeontologists base their work on the

shape of fossils alone， their methods of conservation are

not designed to preserve DNA， Geigl explains.

8. The biggest problem is how they are cleaned. Fossils

are often washed together on-site in a large bath， which can

allow water — and contaminants in the form of contemporary

DNA — to permeate into the porous bones. “Not only is the

authentic DNA getting washed out， but contamination is

getting washed in，” says Geigl.

9. Most ancient DNA specialists know this already， says

Hendrik Poinar， an evolutionary geneticist at McMaster

University in Ontario， Canada. But that doesn’t mean that

best practice has become widespread among those who actually

find the fossils.

10. Getting hold of fossils that have been preserved with

their DNA in mind relies on close relationships between lab-based geneticists and the excavators， says palaeogeneticist

Svante P bo of the Max Planck Institute for Evolutionary

Anthropology in Leipzig， Germany. And that only occurs in

exceptional cases， he says.

11. P bo’s team， which has been sequencing Neanderthal

DNA， continually faces these problems. “When you want to

study ancient human and Neanderthal remains， there’s a big

issue of contamination with contemporary human DNA，” he

says.

12. This doesn’t mean that all museum specimens are

fatally flawed， notes P bo. The Neanderthal fossils that

were recently sequenced in his own lab， for example， had

been part of a museum collection treated in the traditional

way. But P bo is keen to see samples of fossils from every

major find preserved in line with Geigl’s recommendations —

just in case.

Warm and wet

13. Geigl herself believes that， with cooperation

between bench and field researchers， preserving fossils

properly could open up avenues of discovery that have long

been assumed closed.

14. Much human cultural development took place in

temperate regions. DNA does not survive well in warm

environments in the first place， and can vanish when fossils

are washed and treated. For this reason， Geigl says， most

ancient DNA studies have been done on permafrost samples，

such as the woolly mammoth， or on remains sheltered from the

elements in cold caves — including cave bear and Neanderthal

fossils.

15. Better conservation methods， and a focus on fresh

fossils， could boost DNA extraction from more delicate

specimens， says Geigl. And that could shed more light on the

story of human evolution.

(640 words nature )

Glossary

Palaeontologists 古生物学家

Aurochs 欧洲野牛

Neanderthal (人类学)尼安德特人，旧石器时代的古人类。

Permafrost (地理)永冻层

Questions 1-6

Answer the following questions by using NO MORE THAN

THREE WORDS for each answer.

1. How did people traditionally treat fossils?

2. What suggestions do Geigl and her colleagues give on

what should be done when fossils are found?

3. What problems may be posed if fossil bones are washed

on-site? Name ONE.

4. What characteristic do fossil bones have to make them

susceptible to be contaminated with contemporary DNA when

they are washed?

5. What could be better understood when conservation

treatments are improved?

6. The passage mentioned several animal species studied

by researchers. How many of them are mentioned?

Questions 7-11

Do the following statements agree with the information

given in the passage? Please write

TRUE if the statement agrees with the writer

FALSE if the statement does not agree with the writer

NOT GIVEN if there is no information about this in the

passage

7. In their paper published in the Proceedings of the

National Academy of Sciences ， Geigl and her colleagues have

shown what conservation practices should be followed to

preserve ancient DNA.

8. The fossil bones that Geigl and her colleagues studied

are all from the same aurochs.

9. Geneticists don’t have to work on site.

10. Only newly excavated fossil bones using new

conservation methods suggested by Geigl and her colleagues

contain ancient DNA.

11. Paabo is still worried about the potential problems

caused by treatments of fossils in traditional way.

Questions 12-13

Complete the following the statements by choosing letter

A-D for each answer.

12. “This information” in paragraph 3 indicates：

[A] It is critical to follow proper practices in

preserving ancient DNA.

[B] The best way of getting good DNA is to handle fossils

with gloves.

[C] Fossil hunters should wear home-made hammers while

digging up bones.

[D] Many palaeontologists know how one should do in

treating fossils.

13. The study conducted by Geigl and her colleagues

suggests：

[A] the fact that ancient DNA can not be recovered from

fossil bones excavated in the past.

[B] the correlation between the amount of burying time

and that of the recovered

DNA.

[C] the pace at which DNA degrades.

[D] the correlation between conservation practices and

degradation of DNA.

(by Zhou Hong)

Suggested answers and explanations

1. washing， brushing， varnishing 见第一段。

2. handling with gloves / freezing samples ( any one of

the two ) 见第二段。

3. losing authentic DNA / being contaminated /

contamination ( any one of the three) 见第八段 “Not only is

the authentic DNA getting washed out， but contamination is

getting washed in” (答being contaminated或 contamination比较保险)

4. they are porous porous 的意思是多孔的。见第八段 “。。。

which can allow water — and contaminants in the form of

contemporary DNA — to permeate into the porous bones.”

5. human evolution 见第十五段。其中“shed light on sth”的意思是使某事显得非常清楚，使人了解某事。

6. 4 分别为第四段的“an extinct cattle species， called

an aurochs”，即欧洲野牛，已经绝迹;第十一段 “Neanderthal”，

是人类学用语，尼安德特人，旧石器时代的古人类;第十四段“woolly

mammoth”和“cave bear”，其中mammoth是猛犸，一种古哺乳动物。

7. T 见第二段。

8. T 见第四段 “Geigl and her colleagues looked at 3，200-year- old fossil bones belonging to a single individual

of an extinct cattle species， called an aurochs.” 即他们研究的骨化石是一头欧洲野牛身上的。

9. NG

10. F 见第十二段第一、二句话。

11. T 见第十二段末句 “But P bo is keen to see samples of

fossils from every major find preserved in line with Geigl’s

recommendations — just in case.” 意即为保险起见，Paabo还是非常希望见到用Geigl建议的方法保存的化石样本。“just in case”

的意思是以防万一，就是Paabo对用传统保存处理的化石不放心的意思。

12. A 见第三段。This information就是前一句中 “。。。

just how important conservation practices can be” (to

preserve good DNA)。“be hammered”之中hammer一词的意思是持续重复强调。

13. D 面信息。需要理解文章各处关于Geigl和她的同事所作的研究