题目内容
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Astrobiology, a branch science combining many other branches, studies the life on Earth.
A．Y
B．N
C．NG
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Aliens
Are there other forms of life in the universe'？ The scientific search for extraterrestrial (ET) life forms has been bolstered by two recent discoveries. First, the discovery of life forms in exotic environments on Earth indicates that life is very hearty and can adapt to the strangest and most hostile environments. Second, astronomers found planets orbiting stars besides our sun—over 50 extrasolar planets have been discovered as of 2001. Are there alien life forms on any of these planets？
If alien life does exist, what might it be like？ Would it be simple forms of life such as bacteria, viruses or algae, or more advanced, multi-cellular creatures, perhaps even intelligent beings？ Would aliens be animals, plants or have characteristics of both？ Would they have arms and legs and walk upright as we do？ Would they depend upon vision as their primary sense or use another way to gather information about their surroundings？ Would they "breathe" oxygen or some other gas？
Greetings, Carbon-based Bipeds(两足动物)!
Most of us picture alien life the way it's portrayed in movies, where aliens are commonly depicted as human-like forms because they use actors either to play the roles directly in make up or to be models for computer-generated animation. Also, audiences relate to human-like aliens better than to more exotic, monster like. However, the human body plan bilateral symmetry with one
head, two legs and two arms—stems from when early animals such as lizard, crocodile, or dinosaur colonized the Earth's land masses, and it seems unlikely that such a shape would evolve on an alien world. So, let's forget Hollywood for the moment and look closely at the real science of astrobiology.
Astrobiology is the scientific study of life in the universe. Astrobiologists seek to understand (among other things) how life arose and evolved on Earth, what governs the way life is organized and what makes a planet habitable.
Astrobiology combines the disciplines of biology, chemistry, physics, geology and astronomy. Often, astrobiologists must use the information learned about life on Earth as a guide for studying life elsewhere. Let's examine some of the unusual things that we have learned from life on Earth:
Life in the Extreme
Up until about 30 years ago, it was believed that all life on Earth was dependent upon energy from the sun. Furthermore, it was thought that you would probably not find life where temperatures were extremely hot, like in geysers or hot springs, or extremely cold,' like in the Antarctic desert.
These ideas changed when oceanographers explored hydrothermal vents, openings in the ocean floor where extremely hot, mineral-rich water erupts from the crust. Hydrothermal vents are located several miles below the surface, on the ocean floor, where the surrounding water is at or near freezing, it is absolutely dark and the pressure is high. In organized communities around the bases of these vents, called black smokers, scientists found clams, crabs and exotic, giant tubeworms measuring 6 feet (2 meters) long. The water coming out of these vents is 230 to 662 degrees Fahrenheit (110 to 350 degrees Celsius).
How can these animals survive so far from the sunlight, under these extreme conditions？ In the water, scientists found species of bacteria that split hydrogen sulfide(硫化物)from the water to get energy to make organic compounds. The tubeworms have bacteria in their tissues that help them derive energy from the water. The clams feed on the bacteria, and the crabs feed on the tubeworms.
The discovery of hydrothermal-vent communities showed that it is possible for life to evolve in places without light from the sun, and in other worlds without sufficient light from the parent star. In view of the discovery of hydrothermal vents, it may be possible that life exists on Europa, an icy moon of Ju
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B．N
C．NG
"Venus has nothing," is the blunt word from planetologist Kevin Zahnle of NASA Ames Research Center in Calitfornia's Silicon Valley. "We've written it off."
Yet a small group of advanced life-forms on Earth begs to differ, and theorizes that bizarre microbial ecosystems might have once populated Venus and, in fact, may be there still. Members of this loose band of researchers suggest that their colleagues have water too much on the brain, and are, in a sense, H2O chauvinists (盲目的爱国者).
"Astrobiologists are neglecting Venus due more to narrow thinking than actual knowledge of the environment, or environments, where life can thrive," says Dirk Schulze-Makuch, a geobiologist at the University of Texas at E1 Paso who recently co-authored a Venus-boosting paper in Astrobiology with colleague Louis Irwin.
The bias against life on Venus is partly rooted in our own biology. Human experience instructs that liquid water, preferably lot of it, is essential for life. In search for extraterrestrial life, we obsess over small rivers in Mars' surface apparently carved by ancient gushes of water, and delight in hints of permafrost (永久冻结带) just underneath its surface. (By comparison, Venus isn't even that interesting to look at: A boring cue ball (台球的白色母球) for backyard astronomers, its clouds reflects 75% of visible light.) Attention and then funding follow the water: Three more landers will depart for Mars this spring, and serious plans for sample-return missions hover in the midterm future.
"If you have limited resources, you base exploration on what you know," says Arizona State University planetary geologist Ronal Greeley. It's like losing your keys on the way home at night: The first place you look is under the streetlights not because they're more likely to be there, but because if they are, you'll spot them. For astrobiologists, the streetlights are the spectral (光谱的)lines for water, and they've spotted that potential on Mars, Jupiter's moon Europa, even Neptune's moon Triton. Not on the baking rocky flats of Venus.
Venus is the hottest of all the nine planets in the solar system because______.
A．it is not so close to the Sun as Mercury
B．many volcanoes spread the whole planet
C．it is covered by a thick layer of cloud
D．greenhouse effect is uncontrollable on it
"Venus has nothing," is the blunt word from planetologist Kevin Zahnle of NASA Ames Research Center in California&39;s Silicon Valley. "We&39;ve written it off. "
Yet a small group of advanced life-forms on Earth begs to differ. and theorizes that bizarre microbial ecosystems might have once populated Venus and. in fact. may be there still. Members of this loose band of researchers suggest that their colleagues have water too much on the brain, and are, in a sense, H2O chauvinists（盲目的爱国者）．
"Astrobiologists are neglecting Venus due more io narrow thinking than actual knowledge of the environment,or environments. where life can thrive." says Dirk Schulze-Makuch, a geobiologist at the University of Texas at El Paso who recently co-authored a Venus-boosting paper in Astrobiology wich colleague Louis Irwin.
The bias against life on Venus is partly rooted in our own biology. Human experience instructs that liquidwater, preferably lot of it. is essential for life. In search for extraterrestrial life, we obsess over small rivers in Mars&39; surface apparently carved by ancient gushes of water. and delight in hints of permafrost (永久冻结带) just underneath its surface. (By comparison. Venus isn&39;t even that interesting to look at:A boring cue ball (台球的白色母球) for backyard astronomers, its clouds reflects 75% of visible light.) Attention and then funding follow the water: Three more landers will depart for Mars this spring. and serious plans for sample-return missions hover in the midterm future.
"If you have limited resources, you base exploration on what you know." says Arizona State University planetary geologist Ronal Greeley. It&39;s like losing your keys on the way home al night: The first place you look is under the streetlights not because they&39;re more likely to be there. but because if they are. you’llspot them. For astrobiologists. the streetlights are the spectral (光谱的) lines for water. and they&39;ve spotted that potential on Mars, Jupiter&39;s moon Europa. even Neptune&39;s moon Triton. Not on the baking rocky flats of Venus.
测试题
Venus is the hottest of all the nine planets in the solar system because_____________.
A.it is not so close to the sun as Mercury
B.many volcanoes spread the whole planet
C.it is covered by a thick layer of cloud
D.greenhouse effect is uncontrollable on it
Passage One
At Benjamin N. Cardozo High School in Queens, he was known as Matthew Kaye, an earnest social studies teacher shepherding his ninth-and tenth-grade students across the panorama of global history. But out of school-on the professional wrestling circuit- he was Matt Striker, a muscleman known for a move called the lung blower.
His double life may have body-slammed ins teaching career.
According to city investigators, Mr. Kaye, 31, falsely called in sick for 11 days in December and February when he was actually on the wrestling tour. Faced with disciplinary action, Mr. Kaye resigned in April, but yesterday be said that he hoped to get ins job back
"There are people out there who touch children inappropriately who are still allowed to work, "Mr. Kaye said in a telephone interview. "The only thing I did was I put in sick days instead of personal days, because I didn't know them was a difference."
But Richard J. Condon, the special commissioner of investigation for the city schools, said it was not that simple. Teachers get 10 sick days a year and only 3 of those can he used for personal business.
Investigators from Mr. Condon's office said a woman who identified herself as Mr. Kaye's mother called Cardozo in December and said that he was out because of a family emergency. Mr. Kaye later told an assistant principal at the school flat his sister was ill.
Then Mr. Kaye was absent in February, when wrestling Web sites said that he appeared on die television show "Smack Down!" in a match against Kurt Angle.
Investigators sought to interview Mr. Kaye, but his lawyer canceled the session and Mr. Kaye resigned.
Mr. Kaye eventually provided two notes from doctors for his absences. But investigators questioned their validity and urged the State Health Department's Office of Professional Medical Conduct to investigate and take action.
Passage Two
The evidence of dietary protection against cancer is strongest and most consistent for diets high in vegetables and fruits, according to an earlier report by the World Cancer Research Fund (WCRF).
The WCRF panel of experts concluded that the daily consumption of 400 grains or more of a variety of vegetables and fruits could, irrespective of other diet and lifestyle. patterns, decrease overall cancer incidence by at least 20 per cent, according to the Asia Food Information Centre.
There is convincing evidence that diets high in vegetables and fruits protect against cancers of the mouth and pharynx, oesophagus, lung, stomach, rectum, larynx, pancreas, breast and bladder. High dietary fiber is also associated with lower risk of some cancers, especially bowel cancer.
The recommended daily intake of dietary fiber is 25-30 grams for a healthy adult. This can only be achieved by incorporating high fiber foods such as whole grains, vegetables, fruit, nuts and seeds into eating patterns every day and/or using a bran supplement.
Adequate fruit and vegetable intake has a protective effect, helping ward off chronic diseases while helping to elevate resistance to infections disease and reduce nutritional deficiencies. Fruit and vegetables actively promote health by providing bodies with essential vitamins, nutrients, fiber and a myriad of phytochemicals (植物化学物质) which acts as antioxidants (抗氧化剂 in the body. Antioxidants neutralize the free radicals that accelerate the process of cell decay and increase the chances of cells becoming cancerous.
Four hundred grams of fruits and vegetables per person per day (excluding potatoes and other starchy tubers) for the prevention of chronic diseases translates to approximately "5-a-day" that is, eating five or more servings of fruit and vegetables every day.
One serving is roughly the amount that fits into the pa
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B．N
C．NG
