Deck 18: Life in the Universe

Question 1

The analysis of Martian meteorites found on the Earth show that they contain

A) only tantalizing hints of possible life.
B) bacteria with DNA closely related to bacteria on Earth.
C) bacteria with DNA very different from bacteria on Earth.
D) fossilized remains of multi-cellular insects.
E) fossilized remains of small, mammal-like creatures.

Answer 1

A

Question 2

After Mars, the next most likely candidates for life in the solar system are

A) Comets in the Oort cloud.
B) The atmospheres of the Jovian planets.
C) The large moons of the Jovian planets.
D) The largest asteroids.
E) Comets in the Kuiper-belt.

Answer 2

C

Question 3

Which of the following statements about matter-antimatter engines is not true?

A) Matter-antimatter reactions represent the most efficient reactions possible in terms of energy release.
B) Matter-antimatter engines would be possible in theory, but to date, we have no evidence that antimatter exists.
C) One of the major challenges to developing matter-antimatter engines is finding a way to produce enough antimatter.
D) One of the major challenges to developing matter-antimatter engines is finding a way to store antimatter after it is produced.
E) Spacecraft powered by matter-antimatter engines could probably reach speeds of 90 percent of the speed of light.

Answer 3

B

Question 4

Which of the following gases, which we can detect (if present) in infrared spectra, would be a strong indicator of life on another planet?

A) carbon dioxide
B) ozone
C) methane
D) water vapor
E) sulfuric acid

Question 5

At about what fraction of the speed of light do today's spacecraft travel?

A) 1/2
B) 1/10
C) 1/100
D) 1/1,000
E) 1/10,000

Question 6

At present, what is the primary way that astronomers carry out SETI programs (that is, search for extraterrestrial intelligence)?

A) by searching for planets around distant stars
B) by using X-ray telescopes to search for signals from extraterrestrial civilizations
C) by using radio telescopes to search for signals from extraterrestrial civilizations
D) by analyzing high-resolution images of nearby stars in search artificial structures
E) by analyzing the spectra of extra-solar planets in an attempt to detect oxygen

Question 7

Why do some scientists think that Jupiter's existence may have been critical for life to evolve on Earth?

A) It prevented the Earth from migrating outward and thus ensured a stable climate.
B) It prevented the Earth from migrating inward and thus ensured a stable climate.
C) It kicked out many comets from the inner solar system through gravitational encounters, thus ending the heavy bombardment phase of the solar system.
D) Meteorites from Jupiter may have contained the bacteria that started life on Earth.
E) It stabilized the Earth's axis tilt and thus ensured a stable climate.

Question 8

SETI (the Search for Extraterrestrial Intelligence) searches for communications from life in planets and moons

A) within the solar system.
B) around nearby stars.
C) in globular clusters.
D) toward the center of the Milky Way.
E) in other galaxies.

Question 9

In 1974, a radio message was sent out from the Arecibo observatory in Puerto Rico towards a globular cluster, 21,000 light-years away. Approximately how far has this message gotten as of today?

A) It's just beyond the Neptune in our solar system
B) It's just passing through the Oort cloud surrounding our solar system
C) It's just passing stars that are close neighbors to the Sun in the Milky Way
D) It's almost at the center of the Milky Way
E) It's already arrived at the globular cluster

Question 10

How does the Kepler mission plan to detect Earth-like planets around other stars?

A) by measuring the Doppler shift in spectral lines as the central star is tugged to and fro by the planet
B) by observing the slight dip in brightness of the central star as the planet transits
C) by directly imaging the planet in the infrared
D) by observing the spectrum of the planet
E) by measuring the slight shift in position of the central star as it is tugged to and fro by the planet

Question 11

What defines the habitable zone around a star?

A) the region around a star where rocky planets can form
B) the region around a star where humans can survive
C) the region around a star where liquid water can exist on planetary surfaces
D) the region around a star where its ultraviolet radiation is too weak to destroy biological organisms on a planetary surface
E) the region around a star outside of its hot, tenuous corona

Question 12

The Voyager I and II spacecraft visited the Jovian planets in the 1980s. When will they reach the distances of the nearest stars?

A) in our lifetime
B) in our children's lifetime
C) in our grandchildren's lifetime
D) thousands of years from now
E) hundreds of thousands of years from now

Question 13

Which of the following describes a major challenge of interstellar travel at near light speed?

A) Any interstellar journey will take much longer than the lives of the crew members.
B) Time dilation will slow the heartbeats of the crew to a dangerously low rate.
C) Atoms and ions in interstellar space will hit the spacecraft like a flood of dangerous cosmic rays.
D) Asteroid fields floating in interstellar space will present a severe navigational challenge.
E) Supernova explosions could destroy spaceships passing nearby.

Question 14

Which of the following are the best candidates to search for planets that might harbor extraterrestrial life?

A) Halo stars, because planets can form in isolation from disruptive stellar encounters
B) Low mass stars (less than one-tenth of the mass of the Sun), because these are the most common stars in our galaxy
C) Massive stars (greater than twice the mass of the Sun) because they provide more energy to promote biology
D) Solar-mass stars because they have both a large habitable zone and a long stellar lifetime.
E) Binary stars because they provide twice as much energy to promote biology

Question 15

Which of the following was the most important for maintaining the Earth's stable climate over the time it took for large organisms to evolve?

A) sustained volcanic activity
B) the cessation of the heavy bombardment phase
C) plate tectonics
D) the Moon
E) underground sea vents

Question 16

The only place outside of Earth for which there is irrefutable evidence for ancient, microbial life is

A) the Moon.
B) Mars.
C) Europa.
D) Titan.
E) None of the above-there is no irrefutable evidence for life beyond Earth.

Question 17

Where have scientists begun an active search for life beyond the Earth?

A) the Moon
B) Venus
C) Mars
D) Europa
E) Titan

Question 18

Which of the following statements best reflects our current knowledge about the term f lᵢfₑ in the equation Number of Civilizations = N HP × f lᵢfₑ × f cᵢᵥᵢlᵢ ₐtᵢₒn × f nₒw?

A) The value of f lᵢfₑ is either 0 or 1.
B) The value of f lᵢfₑ is between 0 and 1.
C) The value of f lᵢfₑ is less than 0.0000001 .
D) The value of f lᵢfₑ is equal to 1/2.
E) The value of f lᵢfₑ is greater than 10.

Question 19

Which of the following best explains why an interstellar ramjet could, in theory, achieve continuous acceleration?

A) It uses fuel that is more efficient than any other known fuel.
B) It collects its fuel as it goes, rather than having to carry the weight of fuel along with it.
C) It takes advantage of theoretically possible loopholes in Einstein's theory of relativity.
D) It has such a large fuel tank that it will essentially never use up all the fuel it carries.
E) Its speed always gets faster because time dilation changes the rate at which time flows.

Question 20

Why do some scientists say that the Moon may have been important for the evolution of life on the Earth?

A) It created the ocean tides, and life most likely started in tide pools.
B) It stabilized the earth's axis tilt, preventing large climate changes.
C) Meteorites from the Moon brought microscopic life to the Earth.
D) It shielded the Earth during the heavy-bombardment phase of the early solar system.
E) There is no known connection between the Moon and the evolution of life on the Earth.

Question 21

The Pioneer and Voyager spacecraft carry a message from Earth, just in case an alien civilization ever runs across them.

Question 22

Relativistic time-dilation means that astronauts aboard a spaceship traveling close to the speed of light will actually age less than their families left behind on the Earth.

Question 23

The habitable zone around a star refers to the places where living organisms are found.

Question 24

We have already launched a spacecraft bound for Alpha Centauri.

Question 25

What is the evidence that suggests planetary systems are common in the universe?

Question 26

Why might the presence of a giant planet be both good and bad for life on a terrestrial planet in another solar system?

Question 27

There is good evidence that life on Earth was thriving prior to 3.85 billion years ago.

Question 28

Generalizing from a Single Example: Many would argue that our concept of life and intelligence is severely limited by the fact that we have only the "single example" of the Earth. Do you agree with this view (address the questions of life and intelligence separately)? To what extent do you feel that the search for extraterrestrial life is biased by the example of life on the Earth? Does the search for extraterrestrial intelligent life suffer more or less from the same bias?

Question 29

The modern-day organisms that seem oldest, in an evolutionary sense, are microbes that
live in the hot water around volcanic vents on the ocean floor.

Question 30

The Kepler mission, scheduled for launch in 2009, will search for Earth-like planets by looking for the dip in the brightness of a star as a (potential) planet transits across it. Why will this technique actually miss the vast majority of planets around the stars it observes?

Question 31

We have already launched spacecraft whose orbits will carry into interstellar space.

Question 32

If they existed, and if they were watching, a civilization at the center of the Milky Way could have detected our first TV signals by now.

Question 33

What is the Fermi Paradox?

A) Galactic civilizations, like ours, seem forbidden by the laws of physics.
B) Interstellar travel is possible yet would take an infinite amount of time because of relativistic time-dilation.
C) We would be unable to detect an Earth-like planet even at a distance of a few light years.
D) Reasonable assumptions predict that a galactic civilization should have already arisen in the Milky Way. Yet, we have absolutely no evidence for it.
E) The Drake equation predicts that there should be no intelligent life in the Milky Way. Yet, we exist.

Question 34

Although antimatter is an interesting theoretical idea, there is no evidence that it actually exists.

Question 35

The requirement of liquid water is the most severe constraint on the development of life.

Question 36

Which of the following is not a possible solution to the Fermi Paradox?

A) We are the only intelligent civilization to have ever arisen in the Milky Way.
B) Of all of the intelligent civilizations in the Milky Way, none has chosen to create a galactic civilization.
C) There is a galactic civilization, but we are currently unable to detect or recognize it.
D) There is a galactic civilization, but it is being actively hidden from us.
E) Given the current age of our galaxy, there has not been enough time for a galactic civilization to develop.

Question 37

Evolution as a Scientific Theory: Detractors often dismiss evolution by emphasizing the role randomness plays in the theory. They argue that a living creature (such as a human being) is about as likely to have evolved by random chance as a Boeing 747 airplane is of being assembled by a tornado flying through a junkyard. Explain why this vivid analogy is nevertheless fundamentally flawed by correctly explaining the role that randomness plays in the theory of evolution.

Question 38

One idea for interstellar spacecraft involves harnessing energy from nuclear bombs detonated in space.

Question 39

Nearly all of the oxygen in the Earth's atmosphere was originally produced by photosynthesis in the leaves of trees that covered the continents 3.5 billion years ago.

Question 40

Science Fiction as a Driver of Science? This chapter, more than any other in the book, involves familiar themes of science fiction: space travel, extraterrestrial life, extraterrestrial intelligence, and more. Give and discuss two concepts that started out as science fiction but ended up as science fact. Give and discuss an example of an idea from science fiction that will likely never be realized as science fact. Do you think that the rise in popularity of science fiction (Star Trek, Star Wars, and others) has increased or decreased the general public's understanding of science? Explain.

Question 41

Which of the following is not considered crucial for life to exist on some world?

A) Liquid water
B) A source of energy that can be used by life
C) A source of nutrients
D) An atmosphere

Question 42

If we detected an Earth-like planet in the habitable zone around another star, how might we learn whether it harbored life?

Question 43

Why don't we expect to find life on planets orbiting high-mass stars?

A) The lifetime of a high-mass star is too short.
B) The stars are too hot to allow for life.
C) Planets cannot have stable orbits around high-mass stars.
D) The high-mass stars emit too much ultraviolet radiation.

Question 44

The "rare Earth hypothesis" holds that Earth-like planets will prove to be quite rare. Which of the following statements best sums up the current status of the debate over this hypothesis?

A) 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.
B) The debate raged for a while, but is now settled. We are now quite certain that Earth-like planets are common.
C) The debate raged for a while, but is now settled. We are now quite certain that Earth-like planets are rare.
D) It is no longer discussed, because as part of its broad cover-up of UFOs, the United States government has classified all the material relating to this debate as Top Secret.

Question 45

Why do we need new forms of technology to make it possible to journey to the nearest stars within a human lifetime?

Question 46

Briefly explain the meaning of each term in the equation
Number of Civilizations = Np × f lᵢfₑ × f cᵢᵥᵢlᵢ ₐtᵢₒn × f nₒw.

Question 47

Which of the following places is not generally considered a potential home for life in our solar system?

A) Jupiter's atmosphere
B) Mars
C) Europa
D) Titan

Question 48

The Sun's habitable zone ________.

A) extends from some place a little beyond the orbit of Venus to some place near the orbit of Mars
B) consists only of Earth, since Earth is the only planet known to be inhabited
C) extends from the orbit of Earth to the orbit of Jupiter
D) extends from just beyond the orbit of Mercury to just beyond Earth's orbit

Question 49

Why do scientists say that evolution is a "theory"?

A) Because it explains a great deal about life and is supported by an enormous body of evidence
B) Because they are not very confident that it really happened
C) Because it's really just a guess about how life developed on Earth
D) Because it is supported by only a small amount of evidence

Question 50

Based on DNA studies, it seems that all life on Earth ________.

A) shares a common ancestor
B) belongs to one of just two kingdoms: plants and animals
C) arose from one of five distinct ancestors that lived about two billion years ago
D) requires oxygen to survive

Question 51

Which of the following is considered by biologists to be a likely place where life might have first arisen on Earth?

A) In hot water near undersea volcanoes
B) On meteorites that landed on Earth
C) On land surfaces that got moderately heavy rainfall
D) Deep in Earth's core

Question 52

Briefly explain the purpose of the equation
Number of Civilizations = Np × f lᵢfₑ × f cᵢᵥᵢlᵢ ₐtᵢₒn × f nₒw.

Question 53

Briefly summarize current knowledge about the term f lᵢfₑ in the equation
Number of Civilizations = Np × f lᵢfₑ × f cᵢᵥᵢlᵢ ₐtᵢₒn × f nₒw

Question 54

According to fossil evidence, how far back in time did life on Earth exist?

A) About 3.5 billion years or more
B) About 2.0 billion years
C) About 545 million years
D) About 65 million years

Question 55

Briefly explain the Fermi Paradox, namely the paradox of the question "Where are the aliens?"

Question 56

What is a mutation?

A) A change in a living cell's DNA
B) A change in an organism that turns it into a different species
C) A change in the type of food an organism consumes
D) A change in the physical appearance of a living organism

Question 57

Looking for an Earth-size planet around a nearby star (besides the Sun) is like looking for a pinhead located ________.

A) thousands of kilometers away
B) across the street
C) across the length of a football field
D) a few hundred kilometers away

Question 58

Which of the following best describes what we mean by a habitable world?

A) A planet or moon that could support life, if any life happened to be on it
B) A planet or moon with life
C) A planet or moon that lies within its star's habitable zone
D) A planet or moon on which humans could survive if we happened to go there

Question 59

Briefly summarize current knowledge about the term Np in the equation
Number of Civilizations = Np × f lᵢfₑ × f cᵢᵥᵢlᵢ ₐtᵢₒn × f nₒw.

Question 60

How did oxygen (O₂) get into Earth's atmosphere?

A) It was released by life through the process of photosynthesis.
B) It was captured from the solar nebula.
C) It was outgassed from volcanoes.
D) It came from chemical reactions with surface rocks.

Question 61

Which of the following best describes how the Drake equation is useful?

A) It helps us understand what we need to know in order to determine the likelihood of finding other civilizations.
B) It has allowed us to determine the number of civilizations in the Milky Way Galaxy.
C) It allows us to calculate the masses of planets orbiting other stars.
D) It tells us what wavelengths of light will be most useful to examine in the search for extraterrestrial intelligence.

Question 62

In the Drake equation (Number of Civilizations = NHP × flᵢfₑ × fcᵢᵥ × fnₒw ), what do we mean by fnₒw?

A) The fraction of planets with civilizations at the present time (as opposed to only in the past or future)
B) The fraction of planets in the galaxy on which a civilization could theoretically develop right now
C) The fraction of civilizations in the universe that currently are sending messages to us
D) The fraction of all species ever to exist that we currently are aware of

Question 63

At present, what is the primary way that the search for extraterrestrial intelligence (SETI) is carried out?

A) By using radio telescopes to search for signals from extraterrestrial civilizations
B) By analyzing high-resolution images of nearby stars in search of evidence for structures that could not have developed naturally
C) By searching for planets around distant stars
D) By using X-ray telescopes to search for exhaust from interstellar spacecraft
E) By seeking access to the secret records and alien corpses kept at the military's Area 51 in Nevada

Question 64

We are not yet capable of detecting life on planets around other stars. But as our technology develops, our first real chance of detecting such life will probably come from ________.

A) examining spectral lines from the atmospheres of distant planets
B) sending spacecraft to study the planets up close
C) examining high-resolution images of the planets made by orbiting telescopes
D) determining the orbital properties of the planets

Question 65

We have sent several spacecraft on trajectories that will ultimately take them into interstellar space (Pioneer 10 and 11, Voyager 1 and 2, New Horizons). How long will it take these spacecraft to travel as far as the nearest stars?

A) Tens of thousands of years
B) A few hundred years
C) A few decades
D) Never, because they will rust and fall apart
E) About a thousand years

Question 66

If there are other civilizations at present in the Milky Way Galaxy, which statement is almost undoubtedly true?

A) They are far more technologically advanced than we are.
B) They are anatomically much like us, with two arms, two legs, two eyes, and two ears.
C) They have social structures that are completely different from our own; for example, different types of "family" units, and so on.
D) For fun, they enjoy "buzzing" to Earth and temporarily abducting people, showing a clear preference for people located in less-developed rural areas.

Question 67

Which of the following best describes natural selection?

A) It is the idea that organisms with genetic traits that improve their ability to reproduce are more likely to pass those traits on to future generations.
B) It is the idea that the strong survive and the weak die off.
C) It is a guess made by scientists about how life develops, but it has no hard evidence to support it.
D) It is the idea that organisms naturally increase in complexity and intelligence with time.

Question 68

According to current science, why didn't oxygen begin to accumulate in the atmosphere for more than a billion years after life appeared on the Earth?

A) Oxygen was removed from the atmosphere by chemical reactions with surface rocks as quickly as it was released by life.
B) Early forms of animal life consumed the oxygen released by plants during the first billion years of life on Earth.
C) Early life did not release oxygen, and oxygen releasing organisms didn't evolve for a billion years after the earliest life.
D) Oxygen was removed from the atmosphere by dissolving in the ocean as quickly as it was released by life.

Question 69

Einstein's theory of relativity tells us that travelers who make a high-speed trip to a distant star and back will ________.

A) age less than people who stay behind on Earth
B) age more than people who stay behind on Earth
C) have more fun than people who stay behind on Earth
D) never be able to make the trip within their lifetimes

Question 70

Suppose it turns out that one in 1 million stars has a planet that at some point in its history is home to an advanced civilization. Then the total number of civilizations that have arisen in our galaxy would be closest to ________.

A) 400,000
B) 40,000
C) 4,000
D) 400
E) 40

Question 71

Why is Europa considered a good candidate for the possible existence of life?

A) Strong evidence suggests that it has a deep, subsurface ocean of liquid water.
B) The Galileo spacecraft found strange seasonal changes on its surface that look like they could be due to life.
C) It is located within our Sun's habitable zone.
D) It has a thick atmosphere with a surface pressure greater than that on Earth.

Question 72

Suppose that Jupiter had never existed, and there was no planet in our solar system between Mars and Saturn. How would we expect this to have affected Earth?

A) Earth would have been hit by many more comet impacts.
B) Earth's orbit would have been unstable, and our planet would have spiraled into the Sun.
C) There would not have been any effect, since Jupiter is in the outer solar system and Earth is in the inner solar system.
D) There would be no water on Earth.

Question 73

Which of the following best describes the current status of the debate over evidence for life in the Martian meteorite ALH84001?

A) Most scientists find the evidence intriguing but suspect that it can be explained without requiring past life on Mars.
B) Most scientists now agree that the meteorite shows clear evidence of past life on Mars.
C) Most scientists now agree that the meteorite shows no evidence for past life on Mars.
D) Most scientists agree that the evidence would support life if the meteorite truly comes from Mars, but few scientists accept that the meteorite is from Mars and instead think it is an ordinary Earth rock.

Question 74

In the Drake equation (Number of Civilizations = NHP × flᵢfₑ × fcᵢᵥ × fnₒw), we expect the term fcᵢᵥ to be small if ________.

A) most civilizations destroy themselves within just a few hundred years of arising
B) most of the civilizations that have ever existed are still out and about in the galaxy
C) primitive life is common but intelligent life is rare
D) most habitable planets never actually get life on them

Question 75

Which of the following best describes the predominant scientific view of the origin of life on Earth?

A) We may never know precisely how life arose, but current evidence suggests that life probably can arise naturally under the conditions that prevailed on the early Earth.
B) Life probably migrated to Earth from some other world.
C) Life arose through a series of extremely unlikely chemical coincidences, making it seem almost miraculous that life ever came to exist at all.
D) We can describe with great certainty the precise steps by which life arose on Earth.

Question 76

Which of the following describes a major danger of interstellar travel at near-light speed?

A) Atoms and ions in interstellar space will hit a fast-moving spacecraft like a flood of dangerous cosmic rays.
B) Any interstellar journey will take much longer than the lives of the crew members.
C) Time dilation will slow the heart beats of the crew to a dangerously low rate.
D) Asteroid fields floating in interstellar space will present a navigational challenge.

Question 77

Why are fossils of early life on Earth rarer than fossils of plants and animals from the past few hundred million years?

A) Early organisms lacked skeletons and other hard structures that are most likely to be fossilized.
B) Life was far less abundant prior to a few hundred million years ago.
C) Fossils could not form before there was oxygen in the atmosphere.
D) We find fossils in sedimentary layers, and no sediments were deposited until just a few hundred million years ago.

Question 78

When we analyze whether a world is a possible home to life, the key thing we look for is ________.

A) the past or present existence of liquid water
B) evidence of atmospheric oxygen
C) the presence of organic molecules such as amino acids
D) surface coloration changes that could indicate vegetative growth

Question 79

In general, how does the size and location of a star's habitable zone depend on the star's mass?

A) The smaller (less massive) the star, the smaller and the closer-in the habitable zone.
B) The smaller (less massive) the star, the larger and the closer-in the habitable zone.
C) The smaller (less massive) the star, the larger and the farther-out the habitable zone.
D) The habitable zone is always about the same size, but its location moves inward for smaller stars.

Question 80

Which of the following is not key evidence in support of the idea that all life today shares a common ancestor?

A) We have identified fossils of the first life forms that ever existed on Earth.
B) All life uses DNA and the same genetic code.
C) Mapping of gene sequences shows how life is all related.
D) All life builds proteins from the same amino acids and uses ATP to store energy in cells.