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  3. Despite the fact that today virus are known to cause cancer in animals and i

Despite the fact that today virus are known to cause cancer in animals and i

游客2025-04-14  25
问题     Despite the fact that today virus are known to cause cancer in animals and in plants, there exists a great reluctance to accept viruses as being of importance in human cancer. Basic biological phenomena generally do not differ strikingly as one goes from one species to another. It should be recognized that cancer is a biological problem and not a problem that is unique for man. Cancer originates when a normal cell suddenly becomes a cancer which multiplies widely and without apparent restraint. Cancer may originate in many different kinds of cell, but the cancer cell usually continues to carry certain traits of the cell of origin. The transformation of a normal cell into a cancer cell may have more than one kind of cause, but there is good reason to consider the relationships that exist between viruses and cancer.
    Since there is no evidence that human cancer, as generally experienced, is infectious, many persons believe that because viruses are infectious agents they cannot possibly be of importance in human cancer. However, viruses can mutate and examples are known in which a virus that never kills its host can mutate to form a new strain of virus that always kills its host. It does not seem unreasonable to assume that an innocuous latent virus might mutate to form a strain that causes cancer. Certainly the experimental evidence now available is consistent with the idea that viruses as we know them today could be the causative agents of most, if not all cancer, including cancer in man. [br] According to the passage, which is NOT true?
选项 A、Viruses are known to cause cancer in animals and in plants.
B、Many people don’t believe that viruses cause human cancer.
C、Bioloigical phenomena don’t change much in animals and plants.
D、Cancer may originate in certain kinds of cells.
答案 D
解析 根据文章第一段第一句“Despite the fact that today virus are known to cause cancer in animals and in plants，there exists a great reluctance to accept viruses as being of importance in human cancer．”可知，尽管人们都知道病毒可以在动物和植物中引发癌症，却仍不愿意相信病毒对于人类癌症也有着十分重要的作用。由此判断，A、B两项正确；根据文章第一段第二句“Basic biological phenomena generally do not differ strikingly as one goes from one speciesto another．”可知常见的生物现象一般不能鲜明地区分病毒从一种物种转移到另一种物种。所以C正确；D项说癌症可由某些特定细胞转化而来。根据文章第一段倒数第二句“Cancer may originate in many different kinds of cell，but the cancer cell usually continues to carry certain traitsof the cell of origin．”可知，癌症可能由许多种不同的细胞引发，但是癌细胞通常会继续携带原始细胞的某些痕迹。所以D项不正确。据此判断，本题选D。
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