题目

阅读理解 The "junk DNA" may be useful in developing future cancer treatments, according to a new report in the journal Nature Immunology. The discovery was led by Wilmot Cancer Institute investigators and University of Rochester biologists Vera Gorbunova, Ph.D., and Andrei Seluanov, Ph.D.. The DNA elements under research are known as retrotransposons (逆转录转座子). The bad side of them is that if left to run amok, they can give rise to tumors (肿瘤). Researchers, however, discovered that if they are kept in the correct balance and controlled properly, retrotransposons can cause the immune system to destroy cancer. Much of the Gorbunova and Seluanov lab's work involves the blind mole rat (鼹鼠), which lives underground and seems unaffected by cancer. In the latest scientific paper, researchers found that the anti-cancer approaches behind retrotransposons are present in human cells, and planned to use the information to find new ways to stop cancer cell growth. They focus on rats because they are genetically similar to humans and have a diverse range of lifespans (寿命). Gorbunova and Seluanov previously discovered that blind mole rats prevent cancer by activating "concerted cell death," but the approaches at play were a mystery. Now, the researchers believe retrotransposons may be one key piece to the puzzle. Why? Because they discovered that blind mole rats have evolved to retrotransposons to their advantage to kill cancer cells. At first the researchers believed the approaches behind retrotransposons were unique to blind mole rats. However, they found the same approaches at work in human tissue cells. The researchers still need to figure out exactly how blind mole rats have achieved the balance between activating and controlling retrotransposons. For now, though, they will focus on the power of selfish genetic elements to be, well, not so selfish. （1） What is one of reasons for rats to be chosen as study topic? A . They are unaffected by cancer. B . They have overlong lifespans. C . Their genes are alike to humans. D . Their retrotransposons are unique. （2） What does the underlined "amok" in paragraph 2 mean? A . Unbelievably. B . Unreasonably. C . Insensitively. D . Independently. （3） What can we know about the lab's research? A . It developed possible treatments for cancer. B . It transplanted retrotransposons into human. C . It succeeded in balancing retrotransposons. D . It removed junk genes from rats effectively. （4） Which is the most suitable title for the text? A . Blind Mole Rats Fight against Cancer B . "Junk DNA" is a Double-Edged Sword C . Blind Mole Rats: Close Friends of Humanity D . Selfish Genetic Elements Have Great Power 答案： C B A B

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