Deck 15: Life on Other Worlds

Question 1

What molecule carries information from the cell nucleus out into the cell,where specific proteins are made from the information?

A)an enzyme
B)DNA
C)RNA
D)PAH

Answer 1

RNA

Question 2

If you uncoiled and stretched out all of the DNA molecules in a typical human,what would their total length be?

A)about 1 kilometre
B)about 600 kilometres
C)about 1 astronomical unit
D)about 600 astronomical units

Answer 2

about 600 astronomical units

Question 3

What is an offspring born with altered DNA due to radioactivity,cosmic rays,or errors in reproduction called?

A)a mutant
B)a new species
C)a mule
D)a cross-breed

Answer 3

a mutant

Question 4

The first complex life appeared on Earth about 0.5 billion years ago.What period was that?

A)the Jurassic Period
B)the Cambrian Period
C)the Precambrian Period
D)the Neolithic Period

Question 5

The most likely region of the radio spectrum for communication with other civilizations is called "the water hole." What part of the spectrum is this?

A)the part of the spectrum near the radio emission of water
B)the part of the spectrum between the radio emission of hydrogen and oxygen
C)the part of the spectrum between the radio emissions of hydrogen and OH
D)the part of the spectrum near the radio band where water in the Earth's atmosphere strongly absorbs energy

Question 6

What wavelengths are used in current searches for extraterrestrial intelligence by radio telescopes?

A)wavelengths that are longer than the local wavelengths emitted by the Earth's atmosphere
B)wavelengths that are longer than the radio wavelength "noise" naturally emitted by our galaxy
C)wavelengths with the greatest speeds
D)the same wavelengths that are used on Earth for TV signals

Question 7

How is DNA important to a cell?

A)DNA is the cell membrane that allows nutrients to enter the cell and waste to leave the cell.
B)DNA contains the information necessary to make all of the molecules required by the organism and to reproduce itself.
C)DNA contains the information necessary for a cell to defend itself against nearby enemy cells.
D)DNA is the molecule that stores energy within a cell.

Question 8

What is "the habitable zone"?

A)the region on a planet where conditions are acceptable for life to exist
B)a region around a star at a distance where a planet's temperature would permit the existence of liquid water
C)a region only found around G and K stars
D)a region on a young planet at a temperature where amino acids can begin to form DNA molecules

Question 9

What are believed to have been the best places for life to have formed on Earth?

A)near the south pole, on the ice
B)on the continent of Africa, in the areas with no water
C)in liquid water, probably in the oceans or pools of water
D)in volcanoes, where lots of energy was available

Question 10

Which of the following limits the number of technological civilizations in our galaxy?

A)the lifetime of M dwarf stars
B)the number of satellite galaxies of the Milky Way
C)the number of planets per star in a habitable zone for longer than a few billion years
D)the fraction of civilizations that wish to communicate with others

Question 11

Which of the following is used by all known forms of life on Earth as a medium for chemical reactions?

A)gaseous helium
B)frozen carbon dioxide
C)liquid water
D)frozen water

Question 12

Why are massive main sequence stars not likely to have planets that contain life?

A)These stars would sweep away all of the material from which planets could form.
B)These stars are too hot to allow water to exist as a liquid on any planets that might form.
C)These stars are on the main sequence for too short a time to allow life to evolve.
D)These stars are almost always binaries and planetary orbits are unstable around binaries.

Question 13

What molecule in the cell nucleus stores the information to make specific proteins out in the cell body?

A)an enzyme
B)DNA
C)RNA
D)ALH84001

Question 14

Why do some scientists think that the idea of the habitable zone as a fixed distance range from a star is too restrictive?

A)Changes in stars' brightness might change the position of habitable zones.
B)Many forms of life do not require liquid water.
C)Planets may not always keep a constant distance from their star.
D)Liquid water can be maintained by tidal heating.

Question 15

What would scientists say is the best reason to disbelieve UFO reports?

A)Interstellar travel requires huge amounts of time and energy
B)There is no evidence that life exists elsewhere in the universe.
C)No scientist has ever seen a UFO.
D)Scientists believe that any alien civilization would be much more advanced than humans.

Question 16

What is ALH 84001?

A)It is a meteorite that some scientists think shows evidence for life evolving on Mars.
B)It is the compound used by Miller to begin his experiment to produce amino acids.
C)It is the molecule that controls the reproduction of DNA within a cell.
D)It is the molecule that acts as DNA's messenger to assemble proteins from amino acids.

Question 17

What did the Miller experiment create?

A)artificial proteins
B)amino acids
C)simple mould
D)DNA

Question 18

What are a cell's DNA molecules made of?

A)amino acids
B)proteins
C)sugars, phosphates, and bases
D)fatty acids

Question 19

What do DNA molecules contain the patterns for?

A)amino acids
B)proteins
C)phosphates and sugars
D)four kinds of bases

Question 20

Presuming that it takes a few billion years for complex life to evolve in a stable environment,what kind of stars are most likely to currently have inhabited planets?

A)G to K main sequence stars
B)B to A main sequence stars
C)G to K giants
D)white dwarf stars

Question 21

The Viking landers searched for life on ____________________.

Question 22

The most important factor necessary for life to form appears to be the existence of ____________________ on the surface of the planet.

Question 23

Which of the choices below sorts the solar system locations from most-to-least likely for life to develop?

A)Mars, Europa, Enceladus, Titan
B)Mars, Earth's moon, Mercury, Europa
C)Mercury, Venus, Earth's moon, Mars
D)Titan, Europa, Venus, Mars

Question 24

All life on Earth is based on carbon chemistry.

Question 25

Suppose that SETI researchers discovered a radio signal coming from a star in the direction of the centre of the Milky Way that was about 10% closer to the centre than the Sun.Humans sent a reply to this signal immediately,and the aliens replied when they got our message,how long would it take before the alien reply reached Earth?

A)a few years
B)several decades
C)a few hundred years
D)thousands of years

Question 26

What was happening elsewhere in the universe when the first complex life appeared on Earth?

A)The Milky Way galaxy was just forming.
B)Some of the A-type stars we see in the sky today were still forming.
C)The light we see from stars on the other side of the Milky Way was just starting its journey.
D)The late heavy bombardment in our solar system had just finished.

Question 27

All of the terms in the Drake equation are estimates.In the next decade,which of these estimates is likely to improve the most because of better observational data?

A)number of stars in the Milky Way
B)fraction of stars with planets
C)number of planets per star in the habitable zone
D)fraction of planets where life evolves to intelligence

Question 28

A single human cell encloses about 1.5 metres of DNA,containing 4.5 billion base pairs.How far apart are these base pairs in the DNA?

A)3.3×10¹⁰ nm
B)3×10⁹ nm
C)300 nm
D)0.34 nm

Question 29

Suppose you wanted to use your radio telescope to search for signals from alien civilizations.Which stars would be the best targets?

A)Nearby stars, because signals would travel to us in the shortest time.
B)Luminous stars, because they are the easiest to find in the sky.
C)Low-mass stars, because they are more likely to be old.
D)Binary stars, because the chances of habitable planets are twice as high.

Question 30

The oldest easily identifiable fossils appear in sedimentary rocks that formed 3.4 billion years ago during the ____________________ period.

Question 31

When considering the possible number of technologically advanced civilizations in our galaxy,which of the following factors is it useful to consider?

A)the average lifespan of an alien
B)the average lifespan of the civilization
C)the distance to the civilization's planet
D)the type of advanced communication they use

Question 32

DNA is coiled into a tight spiral and makes up the genetic material in a cell.What is that material called?

A)amino acids
B)enzymes
C)nucleus
D)chromosomes

Question 33

The Miller experiment succeeded in creating ____________________.

Question 34

What shows that the building blocks of life form naturally under a wide range of circumstances?

A)the Miller experiment
B)the Chicxulub event
C)the earliest fossils
D)the Drake equation

Question 35

What is important about the habitable zone around a star that makes astronomers believe life could exist there?

A)The level of UV radiation from the star is minimal in the habitable zone.
B)Only in the habitable zone can complex organic molecules be found.
C)Planets in the habitable zone will always have an oxygen atmosphere.
D)In the habitable zone, water can exist as a liquid.

Question 36

How do we usually refer to deoxyribonucleic acid?

A)as vitamin D
B)as reproductive enzymes
C)as RNA
D)as DNA

Question 37

Which of the following is a segment of a chromosome that controls a specific function?

A)DNA
B)RNA
C)a gene
D)an amino acid

Question 38

The portion of the electromagnetic spectrum between the 21 cm line of neutral hydrogen and the 18 cm line of OH is known as the ____________________.

Question 39

Suppose that a lifeform was discovered on Mars,and all of the different individuals in this lifeform had exactly the same genetic material.Why would biologists find this surprising?

A)Mars has never had conditions suitable for life.
B)Lifeforms on other planets are not expected to have genetic material.
C)Mars has had varying environmental conditions through its history.
D)Random variations in genetic material are expected to help lifeforms adapt.

Question 40

The ____________________ is a region around a star where liquid water can exist.

Question 41

What is the significance of the Miller experiment?

Question 42

What is ALH84001,and why is it significant to discussions of the evolution of life?

Question 43

The DNA molecules contain six different bases.

Question 44

Chemical evolution concentrated the various smaller molecules into more stable forms.

Question 45

What is the difference between chemical evolution and biological evolution?

Question 46

What are the three properties of living things that the chapter identifies?

Question 47

The wavelengths that are most likely for communication with other civilizations are those in the water hole.

Question 48

What part of the radio spectrum is thought most likely to be successful for communication with other civilizations? Why?

Question 49

Describe three things that limit travel between stars.

Question 50

How can we select stars with planets that are likely homes for life?

Question 51

If life is to develop on a planet,the planet must lie well inside the inner edge of its star's habitable zone.

Question 52

The oldest fossils on Earth are more than 3 billion years old.

Question 53

DNA molecules cannot be altered by chance errors in reproduction.

Question 54

What did Butler mean when he said,"The chicken is the egg's way of making another egg"?

Question 55

Even if societies on stars in distant galaxies survive at a technological level for only 10 years,that is long enough to establish two-way communication with them.

Question 56

The Miller experiment created synthetic DNA.

Question 57

What kind of information is stored in DNA molecules?

Question 58

The Viking spacecraft searched for life on Mars by looking for the effects of life in the upper atmosphere.

Question 59

How does the likelihood of the survival of technological societies restrict the number of civilizations that we might communicate with?

Question 60

Why must the information in a species' DNA be changeable?