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  3. Turtles have an unfortunate habit of eating plastic objects floating in the sea. These then get trapped in their alimentary cana

Turtles have an unfortunate habit of eating plastic objects floating in the sea. These then get trapped in their alimentary cana

admin2022-11-16  92
问题     Turtles have an unfortunate habit of eating plastic objects floating in the sea. These then get trapped in their alimentary canals, cannot be broken down by the animals’ digestive enzymes and may ultimately kill them. It is widely assumed that this liking for plastics is a matter of mistaken identity. Drifting plastic bags, for instance, look similar to jellyfish, which many types of turtles love to eat. Yet lots of plastic objects that end up inside turtles have no resemblance to jellyfish. Joseph Pfaller of the University of Florida therefore suspects that something more complicated is going on. As he writes in Current Biology, he thinks that the smell of marine micro-organisms which colonize floating plastic objects induces turtles to feed.
    The idea that the smell of plastic rubbish might lure animals to their doom first emerged in 2016. Researchers at the University of California, Davis, noticed that certain chemicals, which are released into the air by micro-organism-colonized plastics, are those which many seabirds sniff to track down food. These chemicals mark good places to hunt because they indicate an abundance of the bacteria that lie at the bottom of marine food chains. The researchers also found that birds which pursue their food in this way are five or six times more likely to eat plastic than those which do not.
    Since turtles are known to break the surface periodically and sniff the air when navigating towards their feeding areas, Dr. Pfaller theorized that they are following these same chemicals, and are likewise fooled into thinking that floating plastic objects are edible.
    To test that idea, he and his colleagues set up an experiment involving loggerhead turtles, a species frequently killed by plastic. They arranged for 15 of the animals, each around five months old, to be exposed, in random order, to four smells delivered through a pipe to the air above an experimental area. Two of the smells proved far more attractive to the animals than the others. When sniffing both the smell of food and that of five-week-old bottles turtles kept their noses out of the water more than three times as long, and took twice as many breaths as they did when what was on offer was the smell of fresh bottle-plastic or clean water vapour. On the face of it, then, the turtles were responding to the smell of old bottles as if it were the smell of food.
    Though they have not yet tested whether the chemical is the culprit, Dr. Pfaller and his colleagues think it is the most likely candidate. In an unpolluted ocean, pretty well anything which had this smell would be edible—or, at least, harmless. Unfortunately, five-week-old plastic bottles and their like are not.
The text is mainly about________.
选项 A、the function of chemicals in turtles’ diet
B、the attraction of plastic rubbish to turtles
C、the reasons of turtles’ liking for plastics
D、the theories on eating habits of turtles
答案C
解析 由题干关键词the text is mainly about可知，本题为主旨要义题，考查对整篇文章主旨大意的理解和概括。文章第一段引出话题，说明了海龟吞食塑料垃圾的后果，并列举了过去和现在的两种海龟喜欢吞食塑料垃圾的可能原因；第二段中，加利福尼亚大学戴维斯分校的研究人员们指出了海鸟喜欢吃塑料垃圾的原因；第三段中，约瑟夫.普法勒博士根据海龟的特性指出海龟吞食塑料垃圾的原因；第四段列举了约瑟夫.普法勒博士为了证明他的理论所做的实验。第五段总结全文，目前还不能确认塑料垃圾中的某些化学物质是导致海龟吞食塑料垃圾的罪魁祸首，但其可能性最大。由此可见，本文主要讨论了海龟喜欢吞食塑料垃圾的原因，C项为正确答案。文章虽然提到了“化学物质”，但“化学物质”只是海龟吞食塑料垃圾原因中的一环，故A项the function of chemicals in turtles’ diet (化学物质在海龟饮食中的作用)应排除；文章一开头就点出了“海龟喜欢吞食塑料垃圾”，这只是本篇文章的切入点，所以B项the attraction of plastic rubbish to turtles(塑料垃圾对海龟的吸引力)很片面，故应排除，文章中虽然提到了海龟喜欢吃塑料，但这只是海龟饮食的一种，而并没有说明海龟其他的饮食习惯，故D项the theories on eating habits of turtles(关于海龟饮食习惯的理论)错误。
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