Deck 18: Life in the Universe

Question 1

Some forms of life on Earth are silicon-based.

Answer 1

False

Question 2

Approximately 10 percent of all life on Earth has been in the form of microorganisms.

Answer 2

False

Question 3

Scientists have shown that ammonia and methane,mixed together with hydrogen,carbon dioxide,or nitrogen,and exposed to electrical sparks,can produce some of the amino acids essential for life.

Answer 3

True

Question 4

Which one of the following is NOT one of the three categories of terrestrial life based on their DNA characteristics?

A) Bacteria
B) Eukarya
C) Archaea
D) Fungi

Question 5

Why was the comet impact a chance happening that benefited the evolution of humans?

A) It deposited a significant amount of nitrogen into the Earth's atmosphere.
B) It led to an increase in global UV radiation,which killed off most of the forests and jungles.
C) Mammals got an evolutionary boost.
D) Plant life began to decline.

Question 6

Which one of the following is NOT one of the six chemical elements commonly found in living organisms?

A) helium
B) hydrogen
C) phosphorus
D) nitrogen

Question 7

The main goal of the Allen Telescope Array is to search for high redshift galaxies.

Question 8

Terrestrial life is composed of 20 different acids that are composed of only 4 different chemical elements.

Question 9

If we model the history of the Earth as a single day,at what time would the first primitive forms of microorganisms appear?

A) 5:00 A.M.
B) 9:00 A.M.
C) 12:00 noon
D) 3:00 P.M.

Question 10

Complex microorganisms that have complex DNA enclosed in a cell nucleus are called:

A) algae
B) bacteria
C) eukaryotes
D) prokaryotes

Question 11

Where do we think life first formed on the Earth?

A) In the air
B) In the oceans
C) On land
D) On asteroids that carried microorganisms to Earth

Question 12

According to the theory of evolution,chemical reactions resulting in the mutation of a molecule are a natural and inevitable occurrence.

Question 13

The four main chemicals of which life on Earth are composed are hydrogen,carbon,oxygen,and sulfur.

Question 14

If we model the age of the universe as a single day,at what time would the earliest traces of humanity appear on the Earth?

A) 11:00:00 P.M.
B) 11:35:00 P.M.
C) 11:53:10 P.M.
D) 11:59:25 P.M.

Question 15

If we model the history of the Earth as a single day,at what time would the first human civilizations appear?

A) 0.2 seconds before midnight
B) 2 minutes before midnight
C) 10:00 P.M.
D) 6:00 P.M.

Question 16

The habitable zone for a 1 M _$\odot$ star ranges from 0.9 to 1.4 AU from the star.

Question 17

Mutations always lead to improvements in an organism's ability to survive and reproduce.

Question 18

What occurred approximately 500 million years ago?

A) The extinction of the dinosaurs
B) The Cambrian explosion
C) The rise of mammals
D) The birth of the first humans

Question 19

The Drake equation estimates the number of solar systems in our galaxy today that may harbor life.

Question 20

In 1952,chemists Harold Urey and Stanley Miller mixed ammonia,methane,and hydrogen in a closed container,zapped it with electrical sparks and found that:

A) they could induce cold fusion to occur
B) they could not induce any amino acids to form
C) single-celled microorganisms had been spontaneously created
D) they had created about half the amino acids contained in DNA

Question 21

If the most pessimistic assumptions in the Drake equation were true,we would:

A) have to wait for approximately 60 million years to get a message back from the nearest intelligent life
B) have to wait for approximately 400 years to get a message back from the nearest intelligent life
C) be the only intelligent life in the universe
D) need to concentrate on the Andromeda galaxy when searching for intelligent life

Question 22

Describe the difference between prokaryotes and eukaryotes.

Question 23

In 1974,astronomers sent a message toward globular cluster M13.If life exists there,and it returns our signal,we won't receive it for at least another 48,000 years.Why not?

A) It will take that long for the space probe carrying our signal to reach the life forms there.
B) Based on the age of the stars in M13,we anticipate it would take that long for a civilization to evolve enough to interpret and respond to our signal.
C) M13 is far enough away that even light takes a very long time to reach it.
D) It will take that long before our Solar System and M13 are properly aligned again.

Question 24

What are the four main chemicals that make up all living organisms on the Earth?

Question 25

If the entire history of the Earth were scaled to fit into one day,what time of day would microorganisms first form,oxygen start becoming a significant component of the atmosphere,and humans split off from their genetic ancestors?

Question 26

Carbon forms the backbone of our DNA because:

A) it is the most abundant element in the universe after hydrogen and helium
B) it reacts easily with oxygen
C) it remains solid even at high temperatures
D) a carbon atom can bond with up to four atoms at a time

Question 27

Examine the figure below. The habitable zone around a star depends most on its:

A) mass and age
B) radius and distance
C) color and distance
D) luminosity and velocity

Question 28

Why is a very hot star not a good candidate to find life?

A) Just because the star is too hot.
B) Because hot stars are only found in the disk of the galaxy which is not conducive to life.
C) Because its lifetime is too short for life to evolve.
D) Because the elements that are around hot stars do not lead to evolution.

Question 29

What is SETI,what is its main objective,and how does it plan to achieve its objective?

Question 30

SETI's Allen Telescope Array (image below)is designed to search __________ for signs of intelligent life.

A) over a thousand stars
B) over a million stars
C) galaxies in the Local Group
D) the 100 closest spiral galaxies

Question 31

Describe the experiments of Harold Urey and Stanley Miller (shown in the image below)in understanding the origins of life.

Question 32

Given the following information,what would be the number of intelligent civilizations in our galaxy? If all stars formed planets; each planet has a 0.1 percent chance of supporting life; every time conditions are right life develops; and only 0.001 percent of the time intelligent life develops surviving indefinitely.

Question 33

Calculate the maximum likelihood that any technically advanced civilization that arose still exists in our galaxy today.

Question 34

What determines whether or not a specific mutation is passed on to future generations?

Question 35

Based on what you know of the Earth's evolution,what percent of Earth-like planets in a star cluster with an age of 2 billion years has intelligent life?

A) 0 percent
B) 10 percent
C) 30 percent
D) 50 percent

Question 36

A value of N = 0.1 for the Drake equation signifies that:

A) 1 out of every 10 solar systems in our galaxy harbors intelligent life
B) 1 out of every 10 solar systems in our galaxy harbors life of some kind
C) 1 out of every 10 galaxies in our universe harbors intelligent life
D) 1 out of every 10 galaxies in our universe harbors life of some kind

Question 37

We search for intelligent life in the universe by:

A) sending out spacecraft with messages on them
B) using radio telescopes to search for radio signals
C) monitoring ultraviolet radiation emitted by stars
D) all of the above

Question 38

Why is a cold star not a good candidate to find life?

A) Just because the star is too cold.
B) Because the habitable zone is very narrow.
C) Because its lifetime is too long for life to evolve.
D) Because the elements that are around cold stars do not lead to evolution.

Question 39

Why would the 21-cm line be a good place to search for signals from intelligent life in the universe?

Question 40

If you wanted to find intelligent life in the universe,what spectral types of stars would you study and why?

Question 41

Name three main dangers (one human and two astrophysical)that threaten the continued existence of human life on Earth.