Is Panspermia Possible
题目：
In 1996,NASA scientists claimed that Allan Hills 84001 (abbreviated ALH 84001),a meteorite containing materials ejected from Mars 15 million years ago, held evidence of Martian microbial life. This discovery renewed interest in a concept that most scientists had long regarded with disbelief, namely panspermia, the idea that life can be passed from one cosmic body to another. But for the idea of panspermia to gain acceptance, three things had to be shown: first, that the event blowing a rock off a planet into space would not sterilize any microbial stowaways; second, that microbes could withstand the rigors of space and also withstand the time span of the trip; and third, that microbes could survive the intense temperatures of the reentry into a foreign planet’s atmosphere. All three of these events had to be tested if the hypothesis was to be accepted on the level of being even theoretically possible.
Researchers approached the problem of whether life could have survived takeoff (and landing as well) in a novel way: by looking at the nature of the meteorite’s magnetism. They found that the outer crust of the meteorite was strongly magnetic. Only a few millimeters into the meteorite, the magnetic field was much weaker but it was still present, and its pattern was differently organized from that of the surface. This jumbled, disorganized pattern suggests that the interior magnetic field was acquired while the rock was part of Mars. The presence of this weak field showed that the interior of the meteorite could not have been heated more than 200°C (and probably much less) in its takeoff from Mars or in its entry through Earth’s atmosphere, for if it had been, its weak magnetic field would have been lost or changed. Further tests showed that the interior of the meteorite could not have been heated by more than 100°C, a temperature that many microbes, especially those in a tough resting stage, can easily survive. Thus, it was shown that survival of the takeoff and landing episodes was possible. But what of the long sojourn in space?
We very much want to know how long a microbe can stay dormant as it travels through space. Since the travel from place to place is never direct but will almost always involve some long-term holding patterns, this is a critical factor in understanding the possibility of panspermia. The 15 million years that ALH 84001 traveled in space may seem to be too long a time for microbes to survive. However, new results from microbiologists studying 250-million-year-old salt deposits challenge this assumption. Such deposits, from the Permian period, are known to enclose many fossilized microbes. In a stunning discovery, some of these “ancient mummies”were brought back to life. While only 2 of 53 salt crystals studied yielded viable activity (suggesting that survival on this scale is rare), the very fact that some seem to have survived greatly increases the odds that panspermia, at least in our solar system, might be a viable event. This study is not without controversy, however, with critics suggesting that the microbes are much younger.
But even if time was not an issue for sleeping microbes, what about the rigors of unprotected space travel? How could any form of life survive the cold vacuum and hard radiation of the outer space environment? Each would seem to be an effective antibiotic. Yet while it is clear that any form of animal or plant soon dies in the vacuum of space, microbes are much hardier life-forms. Just how tenacious these life-forms can be was recently demonstrated by a team that left bacterial spores on a satellite orbiting Earth for five years. Bathed in ultraviolet light, subjected to the vacuum and cold of space, chancing the hits from cosmic rays, the microbial cosmonauts were resurrected and brought back to life. So it can be imagined that some microbe in a resting stage, deeply dormant and perhaps well buried in a speeding comet or asteroid, could indeed make a journey of perhaps thousands or even millions of years of slow drifting in space and finally come to the surface of Earth (or some other planet) in a meteor fall or comet impact.
1
In 1996,NASA scientists claimed that Allan Hills 84001 (abbreviated ALH 84001),a meteorite containing materials ejected from Mars 15 million years ago, held evidence of Martian microbial life. This discovery renewed interest in a concept that most scientists had long regarded with disbelief, namely panspermia, the idea that life can be passed from one cosmic body to another. But for the idea of panspermia to gain acceptance, three things had to be shown: first, that the event blowing a rock off a planet into space would not sterilize any microbial stowaways; second, that microbes could withstand the rigors of space and also withstand the time span of the trip; and third, that microbes could survive the intense temperatures of the reentry into a foreign planet’s atmosphere. All three of these events had to be tested if the hypothesis was to be accepted on the level of being even theoretically possible.
What was the testing of the three events mentioned in paragraph 1 designed to show?
Factual Information Questions事实信息题
AWhether microbial life once existed on Mars
BWhether ALH 84001 is actually from Mars
CWhether ALH 84001 once contained microbes
DWhether it is theoretically possible for life to be transported from one celestial body to another
2
In 1996,NASA scientists claimed that Allan Hills 84001 (abbreviated ALH 84001),a meteorite containing materials ejected from Mars 15 million years ago, held evidence of Martian microbial life. This discovery renewed interest in a concept that most scientists had long regarded with disbelief, namely panspermia, the idea that life can be passed from one cosmic body to another. But for the idea of panspermia to gain acceptance, three things had to be shown: first, that the event blowing a rock off a planet into space would not sterilize any microbial stowaways; second, that microbes could withstand the rigors of space and also withstand the time span of the trip; and third, that microbes could survive the intense temperatures of the reentry into a foreign planet’s atmosphere. All three of these events had to be tested if the hypothesis was to be accepted on the level of being even theoretically possible.
What can be inferred from paragraph 1 about the concept of panspermia?
Inference Questions推理题
AIt was first proposed by NASA scientists.
BIt was developed as a way to account for the presence of life on Mars.
CIt was introduced long before 1996
DIt is regarded by scientists as the most likely explanation for the origin of life on Earth
3
Researchers approached the problem of whether life could have survived takeoff (and landing as well) in a novel way: by looking at the nature of the meteorite’s magnetism. They found that the outer crust of the meteorite was strongly magnetic. Only a few millimeters into the meteorite, the magnetic field was much weaker but it was still present, and its pattern was differently organized from that of the surface. This jumbled, disorganized pattern suggests that the interior magnetic field was acquired while the rock was part of Mars. The presence of this weak field showed that the interior of the meteorite could not have been heated more than 200°C (and probably much less) in its takeoff from Mars or in its entry through Earth’s atmosphere, for if it had been, its weak magnetic field would have been lost or changed. Further tests showed that the interior of the meteorite could not have been heated by more than 100°C, a temperature that many microbes, especially those in a tough resting stage, can easily survive. Thus, it was shown that survival of the takeoff and landing episodes was possible. But what of the long sojourn in space?
Scientists concluded that ALH 84001 “could not have been heated more than 200°C” because its
Rhetorical Purpose Questions修辞目的题
Ainterior still had magnetic properties that ALH 84001 had acquired while on Mars
Binterior had a magnetic pattern associated with microbes in a tough resting state
Couter crust was strongly magnetic
Douter magnetic field began to weaken within only a few millimeters of the crust
4
Researchers approached the problem of whether life could have survived takeoff (and landing as well) in a novel way: by looking at the nature of the meteorite’s magnetism. They found that the outer crust of the meteorite was strongly magnetic. Only a few millimeters into the meteorite, the magnetic field was much weaker but it was still present, and its pattern was differently organized from that of the surface. This jumbled, disorganized pattern suggests that the interior magnetic field was acquired while the rock was part of Mars. The presence of this weak field showed that the interior of the meteorite could not have been heated more than 200°C (and probably much less) in its takeoff from Mars or in its entry through Earth’s atmosphere, for if it had been, its weak magnetic field would have been lost or changed. Further tests showed that the interior of the meteorite could not have been heated by more than 100°C, a temperature that many microbes, especially those in a tough resting stage, can easily survive. Thus, it was shown that survival of the takeoff and landing episodes was possible. But what of the long sojourn in space?
The word “episodes” in the passage is closest in meaning to
Vocabulary Questions词汇题
Aforces
Bmovements
Cevents
Dprocedures
5
We very much want to know how long a microbe can stay dormant as it travels through space. Since the travel from place to place is never direct but will almost always involve some long-term holding patterns, this is a critical factor in understanding the possibility of panspermia. The 15 million years that ALH 84001 traveled in space may seem to be too long a time for microbes to survive. However, new results from microbiologists studying 250-million-year-old salt deposits challenge this assumption. Such deposits, from the Permian period, are known to enclose many fossilized microbes. In a stunning discovery, some of these “ancient mummies”were brought back to life. While only 2 of 53 salt crystals studied yielded viable activity (suggesting that survival on this scale is rare), the very fact that some seem to have survived greatly increases the odds that panspermia, at least in our solar system, might be a viable event. This study is not without controversy, however, with critics suggesting that the microbes are much younger.
The phrase “this assumption” in the passage refers to the assumption that
Factual Information Questions事实信息题
Athe salt deposits studied by microbiologists are 250 million years old
Btravel from place to place is never direct
Cthe new results from microbiologists are correct
D15 million years is too long for microbes on ALH 84001 to travel in space and survive
6
We very much want to know how long a microbe can stay dormant as it travels through space. Since the travel from place to place is never direct but will almost always involve some long-term holding patterns, this is a critical factor in understanding the possibility of panspermia. The 15 million years that ALH 84001 traveled in space may seem to be too long a time for microbes to survive. However, new results from microbiologists studying 250-million-year-old salt deposits challenge this assumption. Such deposits, from the Permian period, are known to enclose many fossilized microbes. In a stunning discovery, some of these “ancient mummies”were brought back to life. While only 2 of 53 salt crystals studied yielded viable activity (suggesting that survival on this scale is rare), the very fact that some seem to have survived greatly increases the odds that panspermia, at least in our solar system, might be a viable event. This study is not without controversy, however, with critics suggesting that the microbes are much younger.
In paragraph 3, why does the author discuss the microbes in Permian salt deposits?
Factual Information Questions事实信息题
ATo argue that these microbes could have survived a journey through space
BTo imply that the 15 million years ALH 84001 spent in space is actually a short time in which panspermia can take place
CTo provide support for the possibility that microbes from another planet might survive a journey lasting millions of years
DTo argue that the odds of surviving a long space journey are so low that it is very unlikely that viable organisms have ever been transferred between cosmic bodies
7
We very much want to know how long a microbe can stay dormant as it travels through space. Since the travel from place to place is never direct but will almost always involve some long-term holding patterns, this is a critical factor in understanding the possibility of panspermia. The 15 million years that ALH 84001 traveled in space may seem to be too long a time for microbes to survive. However, new results from microbiologists studying 250-million-year-old salt deposits challenge this assumption. Such deposits, from the Permian period, are known to enclose many fossilized microbes. In a stunning discovery, some of these “ancient mummies”were brought back to life. While only 2 of 53 salt crystals studied yielded viable activity (suggesting that survival on this scale is rare), the very fact that some seem to have survived greatly increases the odds that panspermia, at least in our solar system, might be a viable event. This study is not without controversy, however, with critics suggesting that the microbes are much younger.
According to paragraph 3, controversy arose over which of the following aspects of the salt-deposit study?
Factual Information Questions事实信息题
AThe number of salt crystals that contained fossilized microbes
BThe viable activity of the microbes associated with the salt deposits
CThe age of the surviving microbes
DThe extent to which the microbes became dormant
8
But even if time was not an issue for sleeping microbes, what about the rigors of unprotected space travel? How could any form of life survive the cold vacuum and hard radiation of the outer space environment? Each would seem to be an effective antibiotic. Yet while it is clear that any form of animal or plant soon dies in the vacuum of space, microbes are much hardier life-forms. Just how tenacious these life-forms can be was recently demonstrated by a team that left bacterial spores on a satellite orbiting Earth for five years. Bathed in ultraviolet light, subjected to the vacuum and cold of space, chancing the hits from cosmic rays, the microbial cosmonauts were resurrected and brought back to life. So it can be imagined that some microbe in a resting stage, deeply dormant and perhaps well buried in a speeding comet or asteroid, could indeed make a journey of perhaps thousands or even millions of years of slow drifting in space and finally come to the surface of Earth (or some other planet) in a meteor fall or comet impact.
Which of the following is NOT mentioned in paragraph 4 as a challenge to the survival of the bacterial spores left on a satellite in space?
Negative Factual Information Questions否定事实信息题
ALow temperatures
BThe vacuum of space
CDebris from asteroids
DCosmic rays
9
Researchers approached the problem of whether life could have survived takeoff (and landing as well) in a novel way: by looking at the nature of the meteorite’s magnetism. They found that the outer crust of the meteorite was strongly magnetic. [■]Only a few millimeters into the meteorite, the magnetic field was much weaker but it was still present, and its pattern was differently organized from that of the surface. [■]This jumbled, disorganized pattern suggests that the interior magnetic field was acquired while the rock was part of Mars. [■]The presence of this weak field showed that the interior of the meteorite could not have been heated more than 200°C (and probably much less) in its takeoff from Mars or in its entry through Earth’s atmosphere, for if it had been, its weak magnetic field would have been lost or changed. [■]Further tests showed that the interior of the meteorite could not have been heated by more than 100°C, a temperature that many microbes, especially those in a tough resting stage, can easily survive. Thus, it was shown that survival of the takeoff and landing episodes was possible. But what of the long sojourn in space?
Look at the four squares [■]that indicate where the following sentence could be added to the passage
Unlike the magnetic field of the crust, it changed direction with great frequency.Insert Text Questions句子插入题
Where would the sentence best fit？Click on a square sentence to the passage.
10
The claim that ALH 84001contained evidence of microbial life has renewed interest in whether panspermia is possible
Prose Summary Questions概要小结题
Select 3 answers
AStudies reveal that microbes within ALH 84001 were already in a tough resting state when they were blown off Mars, thus making it possible for them to survive the journey to Earth
BStudies of microbes in ancient salt deposits support the possibility of panspermia by showing that microbes can come back to life ever after being dormant for millions of years
CBacterial spores left on a satellite show that microbial life can survive the cold temperatures and other challenges posed by unprotected space travel.
DThe magnetic field of ALH 84001 provides evidence that the temperatures related to planetary takeoff and landing could be survived by microbes.
ESimilarities between ALH 84001 and geological deposits from 250 million years ago suggest that panspermia is possible, at least in our solar system.
FThe fact that microbes can survive space travel on meteors raises the possibility that some plants and animals can too
