The "rare Earth hypothesis" holds that Earth-like planets are probably quite rare. Which of the following statements best sums up the current status of the debate over this hypothesis?
  • Half of the habitable worlds in the galaxy actually have life, while the other half don't.
  • Tens of thousands of years
  • barnards star, 61 cygni, Alpha centauri, sirius, spica. (larger M the largest distance) also same order for width of habitable zones and surface temp.
  • We do not have enough data to settle the debate, because counterarguments can be made for each argument suggesting Earth-like planets may be rare.
Fossil evidence suggests that life on Earth arose
  • A planet or moon that could support life, if any life happened to be on it
  • search for extraterrestrial intelligence
  • within a few hundred million years after Earth formed.
  • They are far more technologically advanced than we are
What is a mutation?
  • thousands of kilometers away
  • the lack of an ozone layer
  • just two small branches of the diverse "tree of life" on Earth.
  • A change in a living cell's DNA
Which of the following is NOT considered crucial for life to exist on some world?
  • the lack of an ozone layer
  • Liquid water
  • the Moon
  • Jupiter's atmosphere
How did oxygen (O2) get into Earth's atmosphere?
  • It was released by life through the process of photosynthesis
  • within a few hundred million years after Earth formed.
  • The fossil record, revealed in geological layers of different ages, shows that life on Earth has become more complex over time.
  • 3.5 to 4 billion years
Looking for an Earth-size planet around a nearby star (besides the Sun) is like looking for a pinhead located _________.
  • increases / increases
  • thousands of kilometers away
  • natural selection
  • the lack of an ozone layer
the notion that living organisms with advantages that give them greater reproductive success will survice while others perish
  • geological time scale
  • thousands of kilometers away
  • natural selection
  • drake equation
Earth was born about 4.5 billion years ago. According to current estimates, approximately how long after Earth's formation did the Moon form?
  • a few tens of millions of years later.
  • age less than people who stay behind on Earth
  • within a few hundred million years after Earth formed.
  • thousands of kilometers away
Dinosaurs went extinct, probably because of an impact, about __________ ago.
  • It is larger.
  • Liquid water
  • 65 million years
  • habitable zone
living organisms are able to produce far more offspring than their environment can support
  • theory of evolution
  • thousands of kilometers away
  • Jupiter's atmosphere
  • the lack of an ozone layer
Plants and animals are
  • just two small branches of the diverse "tree of life" on Earth.
  • A planet or moon that could support life, if any life happened to be on it
  • A change in a living cell's DNA
  • It represents our understanding of the process by which evolution occurs.
Why don't we expect to find life on planets orbiting high-mass stars?
  • The lifetime of a high-mass star is too short.
  • They are far more technologically advanced than we are
  • A planet or moon that could support life, if any life happened to be on it
  • In hot water near undersea volcanoes
According to fossil evidence how far back in time did life on Earth exist?
  • thousands of kilometers away
  • In hot water near undersea volcanoes
  • The lifetime of a high-mass star is too short.
  • About 3.5 billion years or more.
How does the habitable zone around a star of spectral type G compare to that around a star of spectral type M?
  • It is larger.
  • In hot water near undersea volcanoes
  • Jupiter's atmosphere
  • Liquid water
The oldest fossil evidence of life dates to about __________ ago.
  • within a few hundred million years after Earth formed.
  • It was released by life through the process of photosynthesis
  • The fossil record, revealed in geological layers of different ages, shows that life on Earth has become more complex over time.
  • 3.5 to 4 billion years
As the mass of the central star increases, the distance to the habitable zone __________ and the size (width) of the habitable zone __________.
  • the lack of an ozone layer
  • natural selection
  • increases / increases
  • geological time scale
At present, what is the primary way that the search for extraterrestrial intelligence (SETI) is carried out?
  • A planet or moon that could support life, if any life happened to be on it
  • We mean the fraction of planets with civilizations at the present time (as opposed to only in the past or future).
  • By using radio telescopes to search for signals from extraterrestrial civilizations
  • They are far more technologically advanced than we are
Based on DNA studies, it seems that all life on Earth _________.
  • the Moon
  • habitable zone
  • shares a common ancestor
  • the lack of an ozone layer
Scientists think it is very unlikely that complex and large forms of life could evolve on planets that orbit stars that are much more massive than the Sun. Why?
  • By using radio telescopes to search for signals from extraterrestrial civilizations
  • It represents our understanding of the process by which evolution occurs.
  • They are far more technologically advanced than we are
  • The expected lifetime of a massive star is too short to allow for the evolution of complex life
The idea that life evolves through time was first suggested in ancient Greece, and it was favored by at least some scientists of the 18th and 19th centuries even before Charles Darwin proposed the theory of evolution. What is the key observational evidence that supports the idea that life on Earth has evolved through time
  • within a few hundred million years after Earth formed.
  • The fossil record, revealed in geological layers of different ages, shows that life on Earth has become more complex over time.
  • 3.5 to 4 billion years
  • Because it explains a great deal about life and is supported by an enormous body of evidence.
Given that the fossil record provides the key evidence for evolution, what is the importance of Darwin's theory of evolution?
  • The expected lifetime of a massive star is too short to allow for the evolution of complex life
  • A planet or moon that could support life, if any life happened to be on it
  • It represents our understanding of the process by which evolution occurs.
  • They are far more technologically advanced than we are
Rank the stars based on the distances to their habitable zones (from the central star), from shortest to longest.
  • They are far more technologically advanced than we are
  • We do not have enough data to settle the debate, because counterarguments can be made for each argument suggesting Earth-like planets may be rare.
  • It represents our understanding of the process by which evolution occurs.
  • barnards star, 61 cygni, Alpha centauri, sirius, spica. (larger M the largest distance) also same order for width of habitable zones and surface temp.
We have sent four spacecraft on trajectories that will take them into interstellar space (Pioneer 10 and 11 and Voyage 1 and 2). How long will it take these spacecraft to travel as far as the nearest stars?
  • increases / increases
  • In hot water near undersea volcanoes
  • the lack of an ozone layer
  • Tens of thousands of years
The Sun's habitable zone _________.
  • Half of the habitable worlds in the galaxy actually have life, while the other half don't.
  • The expected lifetime of a massive star is too short to allow for the evolution of complex life
  • extends from some place a little beyond the orbit of Venus to some place near the orbit of Mars
  • We mean the fraction of planets with civilizations at the present time (as opposed to only in the past or future).
Which of the following statements represent successful tests of the theory of evolution by natural selection?
  • Species often show unique adaptations that are suited to the specific environment in which they live and might be detrimental in other environments, genetic comparisions show that the dna of closely related species is more similar than that of more distantlly related species, over time baceteria tend to resist antibiotic drugs.
  • the Moon
  • Jupiter's atmosphere
  • the lack of an ozone layer
the different time perios of the ___ are defined by changes in fossils found from those time periods
  • Jupiter's atmosphere
  • geological time scale
  • drake equation
  • In hot water near undersea volcanoes
Why do scientists say that evolution is a "theory"?
  • extends from some place a little beyond the orbit of Venus to some place near the orbit of Mars
  • Because it explains a great deal about life and is supported by an enormous body of evidence.
  • search for extraterrestrial intelligence
  • It was released by life through the process of photosynthesis
Einstein's theory of relativity tells us that travelers who make a high-speed trip to a distant star and back will _________.
  • age less than people who stay behind on Earth
  • the lack of an ozone layer
  • They are far more technologically advanced than we are
  • The lifetime of a high-mass star is too short.
highmass main sequence stars have amore distant and wider ___ than low mass
  • Liquid water
  • It is larger.
  • drake equation
  • habitable zone
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