Deck 20: Astrobiology: Life on Other Worlds

Question 1

The best places for life to have formed on Earth are believed to have been

A) near the south pole in places where water is frozen solid as 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.

Answer 1

C

Question 2

As far as we know all forms of life on Earth use ____________ as a medium for chemical reactions.

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

Answer 2

D

Question 3

____________ is the molecule created in the cell nucleus that carries the information to make specific proteins out in the cell body.

A) An enzyme
B) DNA
C) RNA
D) ALH84001
E) PAH

Answer 3

C

Question 4

Why is it believed that life cannot evolve on a planet that orbits a spectral type A, B, or O star?

A) These stars produce too much infrared radiation which would destroy carbon-based organisms.
B) These stars have very small life zones.
C) These stars are not capable of producing planets.
D) These stars do not remain on the main sequence long enough for life to evolve.
E) These stars take too long to form.

Question 5

The number of technological civilizations in our galaxy is limited by

A) the number of stars in our galaxy.
B) the fraction of stars with planets.
C) the number of planets per star in habitable zones longer than a few billion years.
D) the fraction of suitable planets where technical life forms evolve.
E) the number of stars in our galaxy, the fraction of stars with planets, the number of planets per star in habitable zones longer than a few billion years, and the fraction of suitable planets where technical life forms evolve.

Question 6

Replicating early Earth conditions in the lab, the Miller experiment created from inorganic chemicals

A) life.
B) artificial proteins.
C) DNA.
D) simple molds.
E) amino acids.

Question 7

A cell's DNA molecules contain its genetic material. An offspring born with altered DNA due to radioactivity, cosmic rays, or errors in reproduction

A) is called a mutant.
B) is called a new species.
C) is more likely to survive than if its DNA were not altered.
D) is no different than if its DNA were unchanged.
E) will never be able to reproduce itself.

Question 8

Presuming that it takes several billion years of complex live to evolve in a stable environment, the stars most likely to currently have inhabited planets with favorable conditions for life are

A) G to K main-sequence stars.
B) B to A main-sequence stars.
C) G to K giants.
D) white dwarf stars
E) neutron stars.

Question 9

Current searches for extraterrestrial intelligence use radio telescopes at wavelengths

A) which must be shorter than the local wavelengths emitted by Earth's atmosphere.
B) which must be longer than the radio wavelength 'noise' naturally emitted by our galaxy.
C) which must be longer than the local wavelengths emitted by Earth's atmosphere and which must be shorter than the radio wavelength 'noise' naturally emitted by our galaxy.
D) Wrong! Visual light wavelengths are used because radio waves are blocked by dust between the stars.

Question 10

The oldest fossils on Earth

A) show that life began in Africa.
B) show that life began in lush regions between large rivers.
C) show that life began in the oceans.
D) are at least 5 billion years old.
E) at most 5 million years old.

Question 11

DNA is important to a cell because

A) DNA is the cell membrane that allows nutrients to enter the cell and wastes to leave.
B) DNA contains the information necessary to make all of the molecules required by the organism.
C) DNA contains the information necessary for the cell to reproduce itself.
D) DNA is the cell membrane that allows nutrients to enter the cell and wastes to leave, DNA contains the information necessary to make all of the molecules required by the organism, and DNA contains the information necessary for the cell to reproduce itself,
E) DNA contains the information necessary to make all of the molecules required by the organism and DNA contains the information necessary for the cell to reproduce itself.

Question 12

ALH 84001

A) is a meteorite that shows possible evidence for life evolving on Mars.
B) is the compound used by Miller to begin his experiment to produce amino acids.
C) is the amino acid produced in the Miller experiment.
D) is the molecule that controls the reproduction of DNA within a cell.
E) is the molecule that acts as DNA's messenger that assembles proteins from amino acids.

Question 13

The most likely region of the radio spectrum for communication with other civilizations is the water hole, the part of the spectrum

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

Question 14

The habitable zone around a star is

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

Question 15

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

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

Question 16

The first complex multicellular life forms with appendages, etc., appeared on Earth about 0.5 billion years ago during the

A) Jurassic Period.
B) Mississippian Period.
C) Cambrian Period.
D) Precambrian Period.
E) Neolithic Period.

Question 17

A cell's DNA molecules contain its genetic material. DNA molecules contain patterns for the production of

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

Question 18

A cell's DNA molecules contain its genetic material. The DNA molecule can be altered

A) by chance mismatching of base pairs.
B) by damage from exposure to radioactivity.
C) if the host cell is intelligent and determines that an alteration would help the cell survive.
D) by chance mismatching of base pairs, by damage from exposure to radioactivity, and if the host cell is intelligent and determines that an alteration would help the cell survive.
E) by chance mismatching of base pairs and by damage from exposure to radioactivity.

Question 19

A cell's DNA molecules contain its genetic material. These molecules are constructed of

A) amino acids.
B) proteins.
C) sugars, phosphates, and bases.
D) amino acids, proteins, sugars, phosphates, and bases.
E) None of the other choices are correct.

Question 20

What limitation(s) make it impossible to travel between stars?
I) fuel requirements
II) the tremendous distances between stars
III) the finite speed at which objects can travel

A) I
B) II
C) III
D) II & III
E) I, II, & III

Question 21

Which of the following is random?

A) evolution
B) natural selection
C) genetic variation
D) All of the other choices are correct.

Question 22

DNA is coiled into a tight spiral and makes up the ____________ that are the genetic material in a cell.

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

Question 23

Deoxyribonucleic acid contains the genetic information of a cell. It is better known as

A) vitamin D.
B) reproductive enzymes.
C) RNA.
D) DNA.
E) vitamin B12.

Question 24

The process shown above is ____________.

A) cell splitting
B) mutation
C) life formation
D) copying

Question 25

In the Arecibo message shown above, the purple line leads to a purple arc with a letter M, which represents ______________.

A) a common color of the rainbow being transmitted in a region of the EM spectrum that text messages are sent in
B) two letters of the Greek alphabet
C) the radio dish sending a common letter of the English alphabet
D) the radio dish sending a signal

Question 26

Using the above timeline, when did the Cambrian explosion occur?

A) 500 million years ago
B) 600 million years ago
C) 540 million years ago
D) 670 million years ago

Question 27

The Miller experiment succeeded in creating ____________.

Question 28

What life form first appeared on Earth at the 0 mark in the timeline above?

A) dinosaurs
B) microbial
C) mammals
D) humans

Question 29

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

A) 3.3 × 10 ^{− 10} nm
B) 3.3 × 10¹⁰ nm
C) 3 × 10⁹ nm
D) 300 nm
E) 0.33 nm

Question 30

____________ is a segment of a chromosome that controls a specific function.

A) DNA
B) RNA
C) An enzyme
D) A gene
E) An amino acid

Question 31

When considering the number of technologically advanced civilizations in our galaxy, it is useful to consider

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

Question 32

The physical basis of life is/are ____________.

A) carbon
B) water
C) carbon and water
D) carbon, water, and silicon

Question 33

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 there.
B) Only in the life zone can complex organic molecules be found.
C) Planets in the life zone will always have oxygen atmospheres.
D) In the life zone water can exist as a liquid.

Question 34

As shown above, which contributes the most to the total noise in the region that may be likely for interstellar communication?

A) noise from galaxy
B) noise from Earth's atmosphere
C) background radiation and/or noise from Earth's atmosphere
D) quantum mechanical noise

Question 35

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 36

The chemistry of life on Earth takes place in _____________.

A) carbon
B) water
C) silicon
D) methyl alcohol

Question 37

In the Arecibo message shown above, the yellow line leads to a yellow block, which represents ____________.
​

A) Earth
B) the Sun
C) a common shape in the universe
D) All of the other choices are correct.

Question 38

In the Arecibo message shown above, the sky blue line leads to a sky blue letter S and its mirror image, which represent

A) RNA
B) DNA double helix
C) a letter of the English alphabet and the mirror effect
D) periodic signals

Question 39

The complex organism fossil cast shown above first appeared in the __________ period.

A) Pre-Cambrian
B) Cambrian
C) Tertiary
D) Jurassic

Question 40

____________ shows that the building blocks of life form naturally under a wide range of circumstances.

A) The Miller-Urey experiment
B) The Chicxulub event
C) The earliest fossils
D) The Drake equation
E) Stromatolites

Question 41

The DNA molecules contain six different bases.

Question 42

Life forms became large and complex during the ______________ period.

Question 43

All life on Earth is based on carbon chemistry.

Question 44

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

Question 45

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

Question 46

The ____________ molecule is a long carbon-chain molecule that uses information stored in the ____________ molecule to copy the ____________ molecule.

Question 47

The Miller-Urey experiment created synthetic DNA.

Question 48

The Viking landers searched for life on ____________.

Question 49

The unit of heredity is the ____________.

Question 50

The _____________ split lengthwise and duplicate when a cell divides.

Question 51

Because of __________, ___________, and ___________, physical interstellar travel is currently impossible.

Question 52

____________ is the scientific study of the search for life on other worlds and the likelihood that life exists elsewhere.

Question 53

DNA molecules cannot be altered by chance errors in reproduction.

Question 54

Life emerged from the oceans about _________ billion years ago.

Question 55

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

Question 56

____________ are composed of bacterial mats and sediment layers.

Question 57

Choose the correct terms to make the statement correct: ___ Chemical/Biological __ evolution occurs before __ chemical/biological ____ evolution.

Question 58

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

Question 59

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

Question 60

The water hole is between ____-cm to ____-cm.

Question 61

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

Question 62

Life is defined in this text to be a process that extracts energy from the surroundings, maintains itself, and modifies the surroundings to promote its own survival.

Question 63

If life is to develop on a planet, the planet must lie well outside its star's habitable zone, where water is in its icy form.

Question 64

Genetic information is stored in DNA.

Question 65

Natural selection is random.

Question 66

The primordial soup is not organic-rich.

Question 67

The Arecibo radio message to extraterrestrials contains information about the structure of DNA.

Question 68

SETI searches for aliens.

Question 69

Astrobiology is the study of biological life on planets other than Earth.

Question 70

Evolution is random.

Question 71

Life began on Earth as multicellular.

Question 72

Genetic variation is not random.

Question 73

Some M dwarf stars may host planets with life.

Question 74

Ribonucleic acid copies DNA molecules.

Question 75

Cells are tiny bags of carbon.

Question 76

Using laser beams within the solar system to find distances to celestial objects is possible but the length of time needed could be exceeding long for real communication.

Question 77

When a cell divides, the chromosomes split widthwise and duplicate

Question 78

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 79

Our civilization's lifetime needs to be considered in obtaining a realistic estimate of the number of civilizations that we can communicate with in our galaxy.

Question 80

It is expected that planets around high-mass main-sequence stars would be good places to search for extraterrestrial life.