Deck 19: Life in the Universe

Question 1

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

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

Answer 1

C

Question 2

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

Answer 2

C

Question 3

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

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

Answer 3

C

Question 4

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

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

Question 5

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)deep in Earth's core
D)on land surfaces that got moderately heavy rainfall

Question 6

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

Question 7

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

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

Question 8

What is the Fermi Paradox?

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

Question 9

What evidence suggests that life arises relatively easily?

A)Life is currently present in extreme environments like deep ocean volcanic vents.
B)Life was present on Earth soon after the end of the heavy bombardment.
C)All organisms on Earth use DNA as their genetic material.
D)Tardigrades, small animals, can survive exposure to the near- vacuum of space.

Question 10

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 a guess made by scientists about how life develops, but it has no hard evidence to support it.
C)It is the idea that the strong survive and the weak die off.
D)It is the idea that organisms naturally increase in complexity and intelligence with time.

Question 11

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

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

Question 12

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

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

Question 13

Why are relatively few details known about the life that existed on Earth prior to a few hundred million years ago?

A)Many rocks have been transformed by high heat and pressure, destroying any fossils they contained.
B)Older rocks are more rare than younger rocks because of geologic processes like subduction.
C)Nearly all life at that time was microscopic, making it much more difficult to identify.
D)All of the above

Question 14

Which of the following statements best reflects our current knowledge about the term flife in the equation Number of Civilizations = NHP × flife × fcivilization × fnow?

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

Question 15

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

Question 16

What are scientists' best guess(es)for the requirement(s)of life?

A)a source of materials (nutrients)
B)energy to fuel the activities of life
C)liquid water
D)all of the above

Question 17

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)Meteorites from the Moon brought microscopic life to the Earth.
C)It stabilized the earth's axis tilt, preventing large climate changes.
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 18

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

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

Question 19

The figure above shows the geological times scale. Life has existed for of the Earth's history.

A)about 1/2
B)about 1/4
C)about 9/10
D)all

Question 20

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

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

Question 21

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)binary stars, because they provide twice as much energy to promote biology
D)massive stars (greater than twice the mass of the Sun)because they provide more energy to promote biology
E)solar- mass stars, because they have both a large habitable zone and a long stellar lifetime.

Question 22

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

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

Question 23

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

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

Question 24

The figure above shows the geological times scale. Animals have been present on land for approximately _ of the Earth's history.

A)3/4
B)1/5
C)1/2
D)1/10

Question 25

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

Question 26

The figure above shows the geological times scale. Humans have existed for approximately of the Earth's history.

A)10 %
B)0)1 %
C)1 %
D)50%

Question 27

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

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

Question 28

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

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

Question 29

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

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

Question 30

The figure above shows the geological times scale. Humanity's technological society has existed for approximately _ of the Earth's history.

A)0)1 %
B)20%
C)0)00001 %
D)10 %

Question 31

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

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

Question 32

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

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

Question 33

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

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

Question 34

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

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

Question 35

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

Question 36

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

Question 37

Which of the following is not considered a potential solution to the question of why we lack any evidence of a galactic civilization?

A)The galactic civilization is deliberately avoiding contact with us.
B)There is no galactic civilization because we are the first species ever to achieve the ability to study the universe.
C)There is no galactic civilization because all civilizations destroy themselves before they achieve the ability to colonize the galaxy.
D)The galactic civilization probably is undetectable because they operate under different laws of physics from the ones we know.

Question 38

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

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

Question 39

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

A)Life probably migrated to Earth from some other world.
B)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.
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 40

How do scientists determine the age of fossils?

A)They only determine relative ages by assuming that deeper layers of sedimentary rock are older.
B)They use radiometric dating to measure the age of the surrounding rocks.
C)They cannot.

Question 41

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

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

Question 42

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

Question 43

The Sun's habitable zone .

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

Question 44

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

A)Most scientists now agree that the meteorite shows clear evidence of past life on Mars.
B)Most scientists find the evidence intriguing but suspect that it can be explained without requiring 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 45

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

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

Question 46

The figure above shows the geological times scale. The Earth's atmosphere has been oxygen rich for

A)about 500 million years.
B)its entire history.
C)about 2 billion years.
D)a few million years.

Question 47

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 48

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

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

Question 49

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

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

Question 50

What is a mutation?

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

Question 51

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

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

Question 52

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

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

Question 53

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

A)an atmosphere
B)a source of nutrients
C)a source of energy that can be used by life
D)liquid water

Question 54

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 it's really just a guess about how life developed on Earth
C)because it is supported by only a small amount of evidence
D)because they are not very confident that it really happened

Question 55

Which observation(s)and/or experiment(s)demonstrate ways that the chemical building blocks of life (amino acids and DNA bases)could have originated on the early Earth?

A)Amino acids and DNA bases form from simple chemical reactions in experiments simulating the early Earth atmosphere.
B)Experiments have shown that naturally occurring clays can catalyze the formation of RNA strands.
C)These complex molecules have been found within meteorites.
D)All of the above

Question 56

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

Question 57

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

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

Question 58

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

Question 59

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)The debate raged for a while, but is now settled. We are now quite certain that Earth- like planets are common.
B)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.
C)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.
D)The debate raged for a while, but is now settled. We are now quite certain that Earth- like planets are rare.

Question 60

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

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

Question 61

We have already launched a spacecraft bound for Alpha Centauri.

Question 62

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

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

Question 63

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

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

Question 64

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

Question 65

Briefly summarize current knowledge about the term flife in the equation Number of Civilizations = NHP × flife × fcivilization × fnow.

Question 66

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

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

Question 67

The Kepler mission has searched 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 68

Briefly explain the meaning of each term in the equation Number of Civilizations = NHP × flife × fcivilization × fnow.

Question 69

What evidence suggests that life was common on Earth within a billion years of its formation?

A)Life must have formed early in order to produce the variety of lifeforms seen today.
B)rocks older than 3.85 billion years with the carbon- 12 to carbon- 13 ratio typical of living organisms
C)3)5 billion year old rock structures formed by microbes called stromatolites
D)A and C
E)B and C

Question 70

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)a few hundred years
B)tens of thousands of years
C)never, because they will rust and fall apart
D)about a thousand years
E)a few decades

Question 71

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

Question 72

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

Question 73

How do scientists study the history of life on Earth?

A)by studying fossils, the preserved remains of past organisms
B)by using telescopes to look far away, and thus see what life was like in the past
C)by comparing present- day organisms with each other, and assuming past life had mixed traits of present- day organisms
D)by assuming that life in the past was just like present- day life

Question 74

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

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

Question 75

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

Question 76

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

Question 77

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

Question 78

Briefly summarize current knowledge about the term NHP in the equation Number of Civilizations = NHP × flife × fcivilization × fnow.

Question 79

Briefly explain the purpose of the equation
Number of Civilizations = NHP × flife × fcivilization × fnow.

Question 80

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

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