Question

【題目】 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 (兒科腫瘤醫(yī)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.multiplierB.complexC.restrainerD.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

【答案】

【1】B

【2】C

【3】A

【4】D

【解析】

這是一篇說明文。文章主要講述了大象患癌癥的幾率要遠遠低于人類，從科學(xué)的角度對大象和人類的體內(nèi)細胞和一些基因進行了對比來說明。

【1】

細節(jié)理解題。根據(jù)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.（根據(jù)研究結(jié)果，與只有兩個p53基因的人類相比，大象多了38個編碼p53基因的修改副本。p53是一種定義明確的腫瘤抑制因子。）可知，大象有38個基因p53，而人類只有兩個，所以大象有更強大的機制來殺死受損有癌變危險的細胞。故選B。

【2】

詞義猜測題。根據(jù)第一段提到“為什么大象很少得癌癥是一個困惑了科學(xué)家?guī)资�年的謎。”結(jié)合上文According to the results, elephants have 38 additional modified copies of a gene that encodes p53, （根據(jù)研究結(jié)果，大象的p53編碼基因有38個是額外的改良的。）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. （與人類相比，人類只有兩個。此外，大象可能擁有一種更強大的機制來殺死有癌變風(fēng)險的受損細胞。）可知，suppressor應(yīng)是“抑制劑”的意思。選項C“抑制劑”。故選C。

【3】

推理判斷題。根據(jù)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. （但倫敦癌癥研究所的梅爾·格里夫斯教授表示，我們應(yīng)該關(guān)注為什么人類的癌癥水平如此之高。他指出，不健康、致癌行為的增加，如肥胖和日光浴。“你從沒見過大象吸煙!””他補充道。）由此判斷出，Prof Mel Greaves對這個發(fā)現(xiàn)持懷疑的態(tài)度。故選A。

【4】

細節(jié)理解題。根據(jù)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.（根據(jù)希夫曼的說法，大象一直被認為有行走障礙。因為它們的細胞數(shù)量是人類的100倍，所以在它們50到70年的漫長生命中，進入癌變狀態(tài)并導(dǎo)致疾病的可能性應(yīng)該是人類的100倍。）可知，理論上，大象更容易得癌癥。故選D。