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  3. Scientists have created by accident an enzyme (酶) that breaks down plastic drinks bottles. The breakthrough could help solve the

Scientists have created by accident an enzyme (酶) that breaks down plastic drinks bottles. The breakthrough could help solve the

admin2023-01-31  9
问题     Scientists have created by accident an enzyme (酶) that breaks down plastic drinks bottles. The breakthrough could help solve the global plastic pollution crisis by enabling for the first time the full recycling of bottles.
    The new research was spurred by the discovery in 2016 of the first bacterium that had naturally evolved to eat plastic at a waste dump in Japan. Scientists have now revealed the detailed structure of the crucial enzyme produced by the bug.
    An international team then adjusted the enzyme to see how it had evolved, but tests showed they had accidentally made the molecule even better at breaking down the plastic used for drinks bottles. "What actually turned out was we improved the enzyme, which was a bit of a shock," said head researcher Prof. McGeehan, at the University of Portsmouth, UK.
    Currently, the enzyme takes a few days to start breaking down the plastic, far faster than the centuries it takes in the oceans, but the researchers are optimistic this can be speeded up even further and become a viable large-scale process.
    "What we are hoping to do is use this enzyme to turn this plastic back into its original components, so we can literally recycle it back to plastic," said McGeehan. "It means we won’t need to dig up any more oil and, fundamentally, it should reduce the amount of plastic in the environment."
    About 1 million plastic bottles are sold each minute around the globe and, with just 14％ recycled, many end up in the oceans where they have polluted even the remotest parts, harming marine life and potentially people who eat seafood. "Plastic is incredibly resistant to degradation," said McGeehan. "It is one of these wonder materials that has been made a little bit too well."
    Currently those bottles that are recycled can only be turned into opaque fibres for clothing or carpets, while the new enzyme indicates a way to recycle old clear plastic bottles back into new clear plastic bottles.
    "You are always up against the fact that oil is cheap, so plastic is cheap," said McGeehan. "It is so easy for manufacturers to generate more of that stuff, rather than even try to recycle, but I believe there is a public interest here: perception is changing so much that companies are starting to look at how they can properly recycle these bottles."
    Prof. Adisa Azapagic, at the University of Manchester in the UK, agreed the enzyme could be useful but added: "A full life-cycle assessment would be needed to ensure that the technology does not solve one environmental problem—waste—at the expense of others, including additional greenhouse gas emissions."
What is Prof. Adisa Azapagic’s advice concerning the application of the enzyme?
选项 A、Developing technologies to address greenhouse gas emissions.
B、Considering the extra cost involved in producing the enzyme.
C、Assessing its possible negative impact on the environment.
D、Studying the full life cycle of the enzyme as the first step.
答案B
解析 根据题干中的Prof. Adisa Azapagic定位至最后一段。题目询问该教授对酶应用的建议。她提出要对这门技术进行一个完整的生命周期评估(A full life-cycle assessment)，避免解决了某个环境问题，却要以付出产生其他环境问题为代价(at the expense of others)，其中的others指代other environmental problems。之后以增加温室气体排放为例说明(additional greenhouse gas emissions)，因此C项“评估其对环境可能产生的负面影响”点出at the expense of other environmental problems的意思。A项“开发解决温室气体排放的技术”利用文末greenhouse gas emissions制造干扰，增加温室气体排放只是这项技术可能产生的环境问题，而不是这个酶技术要解决的问题。B项“考虑在生产这种酶时的额外成本”利用文中的at the expense of others设干扰，others指代other environmental problems，并非生产流程中的成本问题，故排除B项。D项“第一步是研究酶的整个生命周期”利用full. 1ife cycle作干扰，文中full-life cycle修饰的是assessment，指对这项技术的全流程评估，而不是酶本身的生命周期。
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