题型：阅读理解 题类：常考题 难易度：普通
山西省朔州市怀仁县第一中学2017-2018学年高三上学期英语第二次月考试卷
Back in the 1860s, a British scientist named Henry Walter Bates noticed something interesting in the animal world: a kind of butterfly, Common Mormon, can change the pattern on its wings so that it looks like another butterfly species, the Common Rose, which is poisonous for birds to eat.
Bates argued that animals develop this ability to protect themselves from being eaten. This theory had been widely accepted by scientists. But one question remains: how do these animals manage to do that?
After more than 150 years, scientists are finally able to answer that question-it is all down to a gene(基因) called “doublesex", according to a study published on March 6 in the journal Nature.
In fact, scientists have long known that genes are responsible for this useful ability. But until the new study, scientists hadn't been able to find out which genes in particular were responsible.
Scientists at the University of Chicago compared the genetic structures of the Common Mormons that changed their wing patterns with those of ones that did not. And all the results pointed to a single gene, “doublesex”.
This was much to the scientists' surprise. They used to expect that something as complex as this would be controlled by many different genes. For example, one gene would control the color of the upper part of the wing, one would do so for the lower part.
However, the “doublesex” gene doesn't quite do everything by itself. Instead, it acts like a switch-it “tells” other genes to change the wing patterns. Isn't that clever?
Scientists believe that this special ability of the “doublesex” gene on Common Mormon was developed throughout the long history of evolution. “The harmless species gains an advantage by resembling something predators(捕食者) avoid,” Sean Carroll, a scientist told Nature. “it was obvious evidence for natural selection.”
To the Editors: I am surprised to read that Dr. Strojnik ("Direct Detection of Exoplanets," September-October2023) states that we have not yet and cannot directly image exoplanets (外部行星). This is incorrect. NASA/IPAC has a list at exoplanetarchive.ipac.caltech.edu/does/imaging.html. One example is an image of 51 Eridani b. The planet is 2.6 times as massive as Jupiter and has the same radius (半径). Gerard Kriss Space Telescope Science Institute |
Dr. Gerard: I am pleased that my article brought a response. The phrase "planet detection" arouses in people's imaginations beautiful images of planets that are creative artistic representations of novel worlds. But a blur of brightness is not an image. Exoplanet researchers routinely call videos such as the one below of 51 Eridani b "direct images" because the planet's light has been separated from that of its star. "Directly imaged" is the standard language of exoplanet astronomy. But to an optical (光学的) scientist such as myself, there is a strong distinction between direct detection (the planet's light separated from the light of its star) and direct imaging (a proven picture of the exoplanet). From an optical researcher's perspective, a single bright spot simply is not an image. Indeed, even the word "direct" in direct detection is debatable from an optical researcher's point of view. The detection of the light of the exoplanet requires significant processing, adding multiple images and removing starlight based on theoretical models of the source signal. But the interpretation of a bright spot as a planet is only possible upon visual inspection and optimistic thinking. As an optical scientist, I cannot look at a single spot and call it an image of exoplanets. A trajectory (轨迹), or a series of bright points, is not an image of a planet, although it very likely represents something that nowadays is described as an exoplanet. Marija Strojnik |
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