题目内容
9.Astronauts in space may suffer motion sickness,muscle loss,tiredness and bone loss due to low or zero gravity and weightlessness.But scientists at the University of Delaware are experimenting with little worms to better understand how space travel affects astronauts.The millimeter-long worm,called C.elegans,is often used in medical studies because its life is only about two weeks long.Seventy percent of its DNA is the same as human DNA.
Chandran Sabanayagam,a scientist with the University of Delaware,built a microgravity simulator(模拟器)to test how C.elegans would perform in the actual zero gravity of space.
Scientists use a computer to watch the worms as they constantly turn over the simulator.The computer shows the worms as they would look under a microscope.Mr.Sabanayagam says the worms turn around and around in the simulator for about one week before they take them out,looking for changes in the worms'epigenome.The epigenome are chemical markers that relate to microgravity and that tell the DNA in the cells how to perform.They can be changed by the environment.And those changes pass from one generation to the next.
"When the worms are in microgravity environment some epigenomic marks remain even when we put it back into normal ground conditions.So its offspring(后代)keeps this epigenomic memory of the parents'microgravity environment."
The information gathered suggests that the epigenomic marks appear during the early part of a worm's life.Mr.Sabanayagam says identifying epigenomic marks is important for human studies in the future.
Mr.Sabanayagam thinks scientists can find genes(基因)in the human genome(基因组)similar to those in the worms that responded to microgravity.He says scientists could possibly observe those genes closely when astronauts travel in space.
Chandran Sabanayagam expects C.elegans to visit the International Space Station within two years.He hopes information gathered from the worm studies can be used to develop simple,low-cost and quick tests to measure an astronaut's health.
72.What is the purpose of the research?A
A.To seek a way to solve astronauts'healthy problems resulting from weightlessness.
B.To produce medicines from the C.elegans DNA to prevent astronauts from diseases.
C.To see how much similar the C.elegans DNA is to that of human.
D.To prove the practicability of taking the C.elegans to the outer space.
73.What does the underlined word"They"in the paragraph 4refer to?C
A.Scientists.
B.The worms.
C.The epigenome.
D.Astronauts.
74.What happens to the worms during the experiment?B
A.They are put under a microscope and turned around and around.
B.There are some changes in their epigenome with the microgravity environment.
C.Some of them can't adjust to normal ground conditions after the experiment.
D.Chemical markers in them have changed so that their DNA can't perform well.
75.According to the passage,scientistsB.
A.are having difficulties in identifying epigenomic marks in human genes
B.are still on the way to finding human genes that respond to microgravity
C.have sent C.elegans to the International Space Station for the experiment
D.believe using the worms to measure an astronaut's health is costly and quick.
分析 本文属于说明文阅读,作者通过这篇文章主要向我们描述了德拉瓦大学的科学家们正在试验小虫子,以便更好地理解太空旅行对宇航员的影响
解答 72.A.推理判断题.根据第一段He hopes information gathered from the worm studies can be used to develop simple,low-cost and quick tests to measure an astronaut's health可知研究的目的是为了寻求失重对于宇航员的健康产生的问题的解决的途径;故选A.
73.C.词义猜测题.根据文章The epigenome are chemical markers that relate to microgravity and that tell the DNA in the cells how to perform.They can be changed by the environment可知基因组可以随着环境做出改变,指的是表观基因组;故选C.
74.B.推理判断题.根据文章The information gathered suggests that the epigenomic marks appear during the early part of a worm's life.Mr.Sabanayagam says identifying epigenomic marks is important for human studies in the future可知实验过程中蠕虫有与微重力环境的表观基因组发生一些变化;故选B.
75.B.推理判断题.根据文章The information gathered suggests that the epigenomic marks appear during the early part of a worm's life.Mr.Sabanayagam says identifying epigenomic marks is important for human studies in the future可知科学家们还在探索如何将人类基因在微重力方面做一些改变;故选B.
点评 考察学生的细节理解和推理判断能力,做细节理解题时一定要找到文章中的原句,和题干进行比较,再做出正确的选择.在做推理判断题不要以个人的主观想象代替文章的事实,要根据文章事实进行合乎逻辑的推理判断.
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