Deck 20: Astrobiology: Life on Other Worlds

Question 1

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.

Answer 1

amino acids.

Question 2

What limitation(s) make it impossible to travel between stars?

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

Answer 2

I, II, & III

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

RNA

Question 4

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) both A and B
D) Wrong! Visual light wavelengths are used because radio waves are blocked by dust between the stars.

Question 5

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 6

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 7

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 8

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) all of the above.

Question 9

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 10

____ 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
E) Stromatolites

Question 11

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 12

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) all of the above.

Question 13

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 14

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 15

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 16

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 17

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.

Question 18

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 19

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

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

Question 20

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) all of the above.
E) none of the above.

Question 21

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

Question 22

The Miller experiment succeeded in creating ____________________.

Question 23

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 nm
B) 3.3*¹⁰ nm
C) 3*10⁹ nm
D) 300 nm
E) 0.34 nm

Question 24

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

Question 25

The Viking landers searched for life on ____________________.

Question 26

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

Question 27

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

Question 28

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

Question 29

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 30

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 31

The Miller experiment created synthetic DNA.

Question 32

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

Question 33

____ 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 34

DNA molecules cannot be altered by chance errors in reproduction.

Question 35

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

Question 36

The DNA molecules contain six different bases.

Question 37

All life on Earth is based on carbon chemistry.

Question 38

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 39

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 40

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 41

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

Question 42

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

Question 43

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

Question 44

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

Question 45

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

Question 46

What is ALH 84001 and why is it significant to discussions of the evolution of life?

Question 47

What is the significance of the Miller experiment?

Question 48

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 49

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

Question 50

What is the difference between chemical evolution and biological evolution?

Question 51

Describe three things that limit travel between stars.

Question 52

What kind of information is stored in the DNA molecules?

Question 53

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

Question 54

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