Question

    Why elephants rarely get cancer is a mystery that has confused scientists for decades. A study led by researchers at Huntsman Cancer Institute (HCI), at the University of Utah and Arizona State University may have found the answer. 

According to the results, elephants have 38 additional modified copies of a gene that encodes p53, a definite tumor suppressor, as compared to humans, who have only two. Further, elephants may have a more powerful mechanism for killing damaged cells that are at risk for becoming cancerous. In isolated elephant cells, this activity is doubled compared to healthy human cells, and five times that of cells from patients with Li-Fraumeni Syndrome, who have only one working copy of p53 and more than a 90 percent lifetime cancer risk in children and adults. The results suggest extra p53 could explain elephants’ increased resistance to cancer.

“Nature has already figured out how to prevent cancer. It’s up to us to learn how different animals overcome the problem so we can adapt those strategies to prevent cancer in people,” says co-senior author Joshua Schiffman, M.D., pediatric oncologist (儿科肿瘤医生) at Huntsman Cancer Institute, University of Utah School of Medicine.

But Prof Mel Greaves, from the Institute of Cancer Research in London, says we should focus on why humans have such high levels of cancer. He pointed to the rise of unhealthy, cancer-causing behaviors, such as obesity and sunbathing. “You’ve never seen an elephant smoke!” he added.

According to Schiffman, elephants have long been considered a walking problem. Because they have 100 times as many cells as people, they should be 100 times more likely to have a cell slip into a cancerous state and cause the disease over their long life span of 50 to 70 years. And yet analysis of a large database of elephant deaths estimates a cancer death rate of less than 5 percent compared to 11 to 25 percent in people.

1.Why are elephants less likely to get cancer than humans?

A.Elephants are bigger than humans.

B.Elephants have more p53 genes and mechanism killing damaged cells.

C.Elephants are not as clever as humans in walking.

D.Elephants eat more than humans.

2.Which of the following can be the equivalent of the underlined word “suppressor”?

A.multiplier B.complex C.restrainer D.coordinator

3.What’s Prof Mel Greaves’ attitude towards the discovery?

A.Doubtful. B.Neutral. C.Critical. D.Favorable.

4.What can we infer from the last paragraph?

A.Elephants have longer life than people.

B.There is no chance that elephants die from cancer.

C.The rate of elephants dying from cancer is increasing.

D.It was thought theoretically that elephants could get cancer more easily.

Answer

1.B

2.C

3.A

4.D

【解析】

这是一篇说明文。文章主要讲述了大象患癌症的几率要远远低于人类，从科学的角度对大象和人类的体内细胞和一些基因进行了对比来说明。

1.

细节理解题。根据第一段中According to the results, elephants have 38 additional modified copies of a gene that encodes p53, a well-defined tumor suppressor, as compared to humans, who have only two.（根据研究结果，与只有两个p53基因的人类相比，大象多了38个编码p53基因的修改副本。p53是一种定义明确的肿瘤抑制因子。）可知，大象有38个基因p53，而人类只有两个，所以大象有更强大的机制来杀死受损有癌变危险的细胞。故选B。

2.

词义猜测题。根据第一段提到“为什么大象很少得癌症是一个困惑了科学家几十年的谜。”结合上文According to the results, elephants have 38 additional modified copies of a gene that encodes p53, （根据研究结果，大象的p53编码基因有38个是额外的改良的。）和下文的as compared to humans, who have only two. Further, elephants may have a more powerful mechanism for killing damaged cells that are at risk for becoming cancerous. （与人类相比，人类只有两个。此外，大象可能拥有一种更强大的机制来杀死有癌变风险的受损细胞。）可知，suppressor应是“抑制剂”的意思。选项C“抑制剂”。故选C。

3.

推理判断题。根据第四段的But Prof Mel Greaves, from the Institute of Cancer Research in London, says we should focus on why humans have such high levels of cancer. He pointed to the rise of unhealthy, cancer-causing behaviours, such as obesity and sunbathing. ＂You’ve never seen an elephant smoke!＂ he added. （但伦敦癌症研究所的梅尔·格里夫斯教授表示，我们应该关注为什么人类的癌症水平如此之高。他指出，不健康、致癌行为的增加，如肥胖和日光浴。“你从没见过大象吸烟!””他补充道。）由此判断出，Prof Mel Greaves对这个发现持怀疑的态度。故选A。

4.

细节理解题。根据最后一段的According to Schiffman, elephants have long been considered a walking problem. Because they have 100 times as many cells as people, they should be 100 times more likely to have a cell slip into a cancerous state and cause the disease over their long life span of 50 to 70 years.（根据希夫曼的说法，大象一直被认为有行走障碍。因为它们的细胞数量是人类的100倍，所以在它们50到70年的漫长生命中，进入癌变状态并导致疾病的可能性应该是人类的100倍。）可知，理论上，大象更容易得癌症。故选D。