TPO60阅读真题+题目+答案下载：Underground Life

TPO60阅读真题+题目+答案下载：Underground Life

[ Paragraph 1] Until about the late 1980s, most scientists believed that life was restricted to the top few meters of the soil or ocean sediments. The few reports of organisms being recovered from great depths within Earth were dismissed as contamination with material from the surface layers. Two technical developments changed this view. The first was the development of drilling techniques that gave confidence that samples could be retrieved from depth without contamination. Samples were recovered using a diamond-studded drill bit that headed a great length of rotating steel pipe from a drilling derrick. A concentrated tracer material was added to the lubricating fluid so that when a deep sample of rock was removed, any contaminated material could be identified and cut away to leave a prist ine sample of rock from deep within Earth. The second development was the advent of techniques for identifying microorganisms without having to grow them in culture. All organisms contain DNA, and their presence can be revealed by dyes that either stain DNA directly or can be attached to nucleic acid probes. By varying the nucleic acid probe, scientists can demonstrate the presence of different types of microorganisms.

1. Select the TWO answer choices that, according to paragraph 1, indicate what scientists bel ieved before the 1980s about underground organisms. To receive credit, you must select TWO answers

A. It was impossible for organisms to live beyond just a few meters underground

B. Organisms were filtered into the soil from ocean sediments.

C. Organisms that were supposedly found at great depths were actually from the surface layers

D. Contamination from the surface layers of the soil was seriously affecting life underground.

2. The word "pristine" in the passage is closest in meaning to

A. Suitable

B. pure

C. precise

D. solid

3. According to paragraph 1, what is the purpose of using concentrated tracer material during drilling?

A. To lubricate the drill

B. To obtain uncontaminated rock samples

C. To cut away the samples of rock

D. To identify rock sample types

4. The word "revealed" in the passage is closest in meaning to

A. added to

B. made known

C. restricted

D. replaced

5. According to paragraph 1, what can be inferred about the new techniques for the identification of underground microorganisms?

A. They depend on growing microorganisms in culture.

B. They sometimes add contaminants to the sample.

C. They involve DNA analysis

D. They cannot demonstrate the presence of different types of microorganisms.

[ Paragraph 2 ] The f irst scientists to use these techniques were involved in the Subsurface Science Program of the United States Department of Energy (DOE). They were interested in the possibility that if organisms existed in the depths of Earth, they might degrade organic pollutants and help maintain the purity of groundwater or, rather less usefully, degrade the containers in which the DOE was proposing to deposit the radioactive waste from nuclear facilities. They demonstrated the presence of many different types of microorganisms in rocks at depths down to 500 meters beneath the surface. Since then, microbes have been discovered in many different types of rocks and deep within ocean sediments. The record depth at which life has been found is at the bottom of a South African gold mine, 3.5 ki lometers below ground Pressure and temperature increase as you go deeper into Earth Some scientists think that subsurface bacteria could 。。。。。此处省略1000字！

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