Deck 6: The Origin and Evolution of Life on Earth

Question 1

A sample of an ancient sedimentary rock contains slightly less of the isotope carbon-13 than normal. One possible explanation for this is that

A) it was a meteorite that fell from the sky
B) some kind of radioactive decay occurred in it in the past
C) it used to be at the bottom of an ancient ocean
D) some kind of biological activity occurred in it in the past

Answer 1

some kind of biological activity occurred in it in the past

Question 2

Stromatolites are

A) fossils of the first organisms to introduce oxygen into the atmosphere
B) fossils of the first multicellular organisms
C) layers of sediment that once contained colonies of ancient microbes
D) fossils of the first eukaryotes

Answer 2

layers of sediment that once contained colonies of ancient microbes

Question 3

The study of stromatolites tells us that the origin of life on Earth must have ocurred

A) more than 3.5 billion years ago
B) exactly 3.5 billion years ago
C) less than 3.5 billion years ago
D) exactly 3.85 billion years ago

Answer 3

more than 3.5 billion years ago

Question 4

Why can studies of carbon isotopes be used to detect the presence of past biological activity in rocks?

A) living organisms absorb only the most common carbon isotope
B) living organisms remove all carbon from rocks
C) living organisms absorb certain carbon isotopes more easily than others
D) carbon isotopes are found only in living organisms

Question 5

Organisms close to each other on the "Tree of Life"

A) are genetically very different
B) look very similar to the eye
C) are genetically identical
D) are genetically very similar

Question 6

Microbes in the top layers of living stromatolites in western Australia obtain their energy from

A) oxygen in the air
B) poop deposited on them by birds
C) photosynthesis
D) corals that live on their surfaces

Question 7

Where in the "Tree of Life" will current organisms be located that are most closely related to the common ancestor of all life on Earth?

A) at the branch between animals and plants
B) very close to the root
C) at the branch between Archaea and Eukarya
D) very far from the root

Question 8

The most common isotope of carbon is

A) carbon-14
B) carbon-13
C) carbon-12
D) carbon-11

Question 9

Why is the claim of the discovery of microfossils controversial?

A) they are found in rocks from the Hadean Eon
B) it is not clear whether they are of biological or non-biological origin
C) the rocks they are found in are probably contaminated by terrestrial bacteria
D) they are too small to be of biological origin

Question 10

The layered colonies of microbes found in western Australia that resemble some of the Earth's earliest living organisms are called

A) living stromatolites
B) microfossils
C) zircons
D) protocorals

Question 11

Which approach is currently proving to be the most promising way of determining how life on Earth originated?

A) studies of Martian meteorites
B) studies of organisms living around deep-sea ocean vents
C) studies of the fossil record
D) laboratory simulations of conditions present on the early Earth

Question 12

Microfossil evidence suggests that life

A) originated when the Earth formed 4.6 billion years ago
B) originated about 3.0 billion years ago
C) existed 3.85 billion years ago
D) existed before about 3.0 billion years ago and may well have existed before 3.5 billion years ago

Question 13

The most conclusive evidence for microfossils comes from rock samples with

A) an age of 3.5 billion years old
B) ages between 2.7 and 3.0 billion years old
C) ages between 3.2 and 3.5 billion years old
D) an age of 3.85 billion years old

Question 14

Current geological evidence suggests that life

A) must have appeared exactly 3.85 billion years ago
B) could have appeared as soon as the Earth formed, 4.6 billion years ago
C) could have appeared more than 3.85 billion years ago
D) must have appeared exactly 3.5 billion years ago

Question 15

Why have studies of the geological record not enabled us to determine how life on Earth originated?

A) the first living organisms would have left absolutely no trace of their existence
B) life was planted on the Earth by an advanced civilization so there is no evidence in the geological record to find
C) the geological record does not extend back to the time that life originated
D) the oldest rocks are too deep inside the Earth for us to retrieve

Question 16

Carbon-13, with an atomic number of 6 and a mass number of 13 has

A) 6 protons, 6 electrons, and 13 neutrons
B) 6 protons, 7 electrons, and 7 neutrons
C) 7 protons, 7 electrons, and 6 neutrons
D) 6 protons, 6 electrons, and 7 neutrons

Question 17

Stromatolites date back to approximately

A) 4.6 billion years ago
B) 3.5 billion years ago
C) 3.85 billion years ago
D) 4.0 billion years ago

Question 18

Recent evidence that supports the controversial claim based on carbon isotope ratios of biological activity in 3.85 billion year old rocks from Greenland includes the discovery of

A) isotopes other than carbon that also show ratios consistent with biological activity
B) microfossils within the rocks
C) DNA within the rocks
D) oxygen gas trapped within the rocks

Question 19

Recent evidence that supports the controversial claim based on carbon isotope ratios of biological activity in 3.85 billion year old rocks from Greenland includes the discovery of

A) DNA within the rocks
B) microfossils within the rocks
C) similar carbon isotope ratios in other rocks of comparable age
D) oxygen gas trapped within the rocks

Question 20

Carbon isotope evidence from rocks found in Greenland, although controversial, suggests that life may have

A) existed before about 3.0 billion years ago and may well have existed before 3.5 billion years ago
B) originated about 3.0 billion years ago
C) existed 3.85 billion years ago
D) originated when the Earth formed 4.6 billion years ago

Question 21

According to modern biological evidence, modern DNA-based life may have arisen from an earlier

A) RNA world
B) bacterial world
C) protein world
D) extraterrestrial world

Question 22

One type of early pre-cell (vesicle) probably consisted of small droplets of

A) water
B) clay
C) concentrated amino acids
D) nucleic acids

Question 23

Life probably did not originate on the land surface because

A) impacts would have destroyed any life that appeared
B) water was not plentiful on land
C) there was no ozone layer to shield out harmful UV rays
D) organic materials were not present on the land

Question 24

What was NOT an important source of prebiotic molecules (e.g., amino acids) on the early Earth?

A) outgassing by volcanoes
B) molecules produced in the atmosphere by the action of lightning
C) molecules produced by chemical reactions near deep-sea ocean vents
D) molecules transported to the surface by impacts

Question 25

One factor that hampers the use Miller-Urey experiments in studying the chemical processes that may have occurred on the early Earth is that the

A) contribution from impacts is not well understood
B) composition of the Earth's early atmosphere is not well known
C) amount of water that was present is not known
D) amount of UV radiation present from the Sun cannot be estimated

Question 26

RNA catalysts are known as

A) riboflavins
B) ribozomes
C) ribozymes
D) riboenzymes

Question 27

In 2010, scientists discovered an RNA strand capable of catalyzing biochemical reactions made of

A) 165 bases
B) only 5 bases
C) only 2 bases
D) 1967 bases

Question 28

By studying the "Tree of Life" scientists have been able to deduce that life on Earth most likely

A) was planted on the Earth by an advanced civilization
B) originated close to deep-sea volcanic vents
C) originated in shallow ponds on the Earth's surface
D) was transported from another planet by meteorites

Question 29

Sources of organic molecules on the surface of the early Earth included

A) chemical reactions near the ocean surface
B) chemical reactions near deep-sea vents
C) material from space
D) all of the above

Question 30

Present-day living organisms closest to the root of the "Tree of Life" are

A) aerobic bacteria
B) anerobic bacteria
C) archaea living in both extreme and non-extreme environments
D) eukarya similar to ameoba

Question 31

Why do we think that RNA was probably the first self-replicating molecule?

A) it is able to replicate at high temperatures found near deep-sea ocean vents
B) it is much simpler than DNA
C) in laboratory studies researchers have shown that it is able to catalyze its own replication
D) it is able to replicate using carbohydrates rather than proteins

Question 32

Analysis of comet dust collected and returned to Earth by the Stardust mission has shown that

A) simple life exists in comets
B) organic molecules can form in space and survive the passage through the Earth's atmosphere
C) organic molecules are completely absent in comet dust so impacts could not have made a significant contribution the organic material present on the early Earth
D) impacts must have been the only source of organic material present on the early Earth

Question 33

What is the "chicken-and-egg" type problem we face when trying to decide which came first-proteins or nucleic acids?

A) proteins and nucleic acids probably looked very different before the origin of life
B) nucleic acids cannot replicate without proteins, and proteins cannot be made without nucleic acids
C) early proteins and nucleic acids were very similar to each other
D) proteins and nucleic acids are always present together at the same time

Question 34

In the original Miller-Urey experiment it was assumed that carbon and nitrogen in the early atmosphere were present as

A) carbon dioxide (CO₂) and nitrogen (N₂)
B) carbonates (CO₃^-) and nitrates (NO₃^-)
C) methane (CH₄) and ammonia (NH₃)
D) carbon and nitrogen atoms

Question 35

As life on Earth evolved, its DNA

A) changed gradually into RNA
B) stayed the same
C) became gradually less complex
D) became gradually more complex

Question 36

Why do we think that DNA was probably NOT the first self-replicating molecule?

A) it is able to replicate using carbohydrates rather than proteins
B) it is far to complex to have been the first self-replicating molecule
C) it is able to replicate at high temperatures found near deep ocean vents
D) laboratory have shown that it is able to catalyze its own replication

Question 37

The first self-replicating molecule was probably

A) a simple carbohydrate
B) DNA
C) a simple protein
D) RNA

Question 38

The first molecules of RNA were probably made

A) on the surfaces of clays or other minerals
B) deep within the earth
C) in the atmosphere
D) in space and then transported to the Earth in meteorites

Question 39

Why are clay surfaces good at promoting the formation of biological polymers?

A) they are the only types of material monomers will stick to
B) they bring monomers close together, allowing them to react with each other
C) they are very common on the Earth
D) clays are made of biological polymers

Question 40

Organisms far from each other on the "Tree of Life"

A) are genetically very similar
B) are genetically very different
C) look very similar to the eye
D) are genetically identical

Question 41

Why is the chemical evolution model preferred by scientists over other theories for the origin of life on Earth?

A) it is the theory that best fits the available data
B) because we have been able to create Life in the laboratory
C) because it was written down in ancient scriptures
D) because the other theories have been shown to be incorrect

Question 42

Based on current scientific evidence, what is the likelihood that life on Earth formed spontaneously from increasingly complex chemical reactions?

A) very likely
B) certain
C) impossible
D) very unlikely

Question 43

One type of early pre-cell (vesicle) probably consisted of small droplets of

A) water
B) clay
C) lipids
D) nucleic acids

Question 44

What is one reason that early life formed cells?

A) only cells can replicate
B) cell walls prevent heat from escaping
C) cells help to protect fragile biological molecules from the outside environment
D) biological reactions can occur only within cells

Question 45

Based on current scientific evidence, the theory that has been most successful at explaining the origin of life on Earth is

A) naturism
B) panspermia
C) intelligent design
D) chemical evolution

Question 46

One theory for the origin of life suggests that life formed spontaneously from increasingly complex chemical reactions on the Earth. This is referred to as

A) intelligent design
B) naturism
C) panspermia
D) chemical evolution

Question 47

If we eventually find life on Mars, we could tell if panspermia may have occurred between Mars and Earth if

A) the biochemistry of Martian life is very different than life on Earth
B) the biochemistry of Martian life is very similar to life on Earth
C) Martian life shows evidence for natural selection
D) Martian life is cellular

Question 48

Based on current scientific evidence, what is the likelihood that life on Earth was created by some omnipotent being?

A) very unlikely but not impossible
B) impossible
C) certain
D) very likely

Question 49

The first living organisms probably resembled

A) single-celled eukaryotes
B) multicellular eukaryotes
C) single-celled prokaryotes
D) multicellular prokaryotes

Question 50

The possibility of life being transferred from another planet like Mars largely depends on whether that life can survive

A) being lasted from the parent planet
B) inside the meteorite with very little water present
C) long enough in space to make the journey to Earth
D) the impact onto the Earth's surface

Question 51

What was one reason that RNA was eventually replaced by DNA as the molecule of choice for storing genetic information?

A) the bases that make up DNA became much more common
B) DNA is far more stable than RNA
C) DNA can catalyze its own replication
D) the double helix of DNA is better able to correct errors in replication

Question 52

The first living organisms interacted with the atmosphere

A) sexually
B) symbiotically
C) aerobically
D) anaerobically

Question 53

One theory for the origin of life suggests that the earth and Life were created by some omnipotent being. This is referred to as

A) panspermia
B) intelligent design
C) naturism
D) chemical evolution

Question 54

To date, meteorites have been identified originating from which planets and moons?

A) Mars only
B) All terrestrial planets
C) The Moon and Mars
D) The Moon only

Question 55

The very first living organisms on the Earth were probably

A) chemoheterotrophs
B) photoautotrophs
C) photoheterotrophs
D) chemoautotrophs

Question 56

The first living organisms to develop photosynthesis were probably

A) purple and green sulfur bacteria
B) trilobites
C) cyanobacteria
D) stromatolites

Question 57

Bacteria replicate at

A) a rate that slowly decreases with time
B) a constant rate
C) an exponential rate
D) a rate that slowly increases with time

Question 58

What is one reason that early life formed cells?

A) cell walls prevent heat from escaping
B) cells concentrate molecules together so they can react more easily
C) only cells can replicate
D) biological reactions can occur only within cells

Question 59

Based on current scientific evidence, what is the likelihood that life on Earth was transported to Earth in meteorites?

A) impossible
B) very likely
C) certain
D) possible

Question 60

One theory for the origin of life suggests that life was transported to Earth in meteorites. This is referred to as

A) naturism
B) intelligent design
C) panspermia
D) chemical evolution

Question 61

How long did it take for oxygen to build up in the Earth's atmosphere to its present levels?

A) 545 million years
B) 360 million years
C) 2 billion years
D) 3.5 billion years

Question 62

The point in time at which oxygen started to build up in the Earth's atmosphere is referred to as the

A) great oxidation event
B) great oxygen crisis
C) great oxygenation event
D) great photosynthetic event

Question 63

The study of 2-3 billion year old banded iron formations shows that

A) the amount of oxygen in the Earth's atmosphere has remained constant throughout its history
B) Earth's atmosphere contained much more oxygen in the past compared to today
C) there was no oxygen in the Earth's atmosphere at that time
D) Earth's atmosphere contained much less oxygen in the past compared to today

Question 64

During the Carboniferous Period,

A) the carbon dioxide cycle started to operate for the first time
B) carbon-rich meteorites impacted the Earth
C) the first carbon-based life appeared
D) land was covered with dense forests with the appearance of the first insects and amphibians

Question 65

Most likely, oxygen was first released into the atmosphere by

A) the decomposition of dead organisms
B) plants
C) cyanobacteria
D) oxidation reactions

Question 66

An explosion of genetic diversity similar to that which occurred during the Cambrian Period hasn't happened recently, most likely because

A) evolution of life on Earth is no longer occurring
B) such an explosion can occur only for simple organisms and not complex ones
C) there are no more ecological niches available to allow this to happen
D) of the widespread presence of efficient predators that make it much more difficult for entirely new organisms to appear

Question 67

What is one piece of evidence that some organelles like mitochondria and chloroplasts within eukaryotes used to be independent prokaryotes that were incorporated into eukaryotic cells?

A) prokaryotes are seen incorporating into cells today
B) organelles float around independently inside eukaryotic cells
C) the DNA inside organelles is not made of the same four bases as the DNA in the host cells
D) they have their own DNA and reproduce independently of the host cell

Question 68

What happened at the start of the Cambrian Period?

A) the first oxygen-producing bacteria appeared
B) the first dinosaurs appeared
C) early humans first appeared
D) an explosion of genetic diversity appeared, leading to the appearance of the first animals

Question 69

All multicellular organisms are

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

Question 70

The Carboniferous Period began about

A) 475 million years ago
B) 65 million years ago
C) 360 million years ago
D) 545 million years ago

Question 71

The colonization of land by plants appears to have begun about

A) 545 million years ago
B) 360 million years ago
C) 65 million years ago
D) 475 million years ago

Question 72

The first eukarya appeared

A) 4.6 billion years ago
B) around 3.5 billion years ago
C) 4.0 billion years ago
D) at least 2.1 billion years ago or perhaps even earlier

Question 73

The colonization of life onto land was closely tied to the

A) appearance of multicellular organisms
B) development of photosynthesis
C) oceans being overcrowded
D) development of the ozone layer

Question 74

The Cambrian Explosion began approximately

A) 2.1 billion years ago
B) 545 million years ago
C) 360 million years ago
D) 65 million years ago

Question 75

The relationship between organelles and their host cells can best be described as

A) viral
B) sexual
C) symbiotic
D) parasitic

Question 76

Aerobic organisms first started building up oxygen in the Earth's atmosphere around

A) 4.6 billion years ago
B) 3.5 billion years ago
C) 4.0 billion years ago
D) 2.4 billion years ago

Question 77

What is one piece of evidence that some organelles like mitochondria and chloroplasts within eukaryotes used to be independent prokaryotes that were incorporated into eukaryotic cells?

A) the DNA inside organelles is not made of the same four bases as the DNA in the host cells
B) organelles float around independently inside eukaryotic cells
C) prokaryotes are seen incorporating into cells today
D) organelles are very similar to present-day bacteria, suggesting a common ancestor

Question 78

The fossil fuel deposits we use today are the remains of organisms from which period in Earth's history?

A) The Cretaceous Period
B) The Carboniferous Period
C) The Cambrian Period
D) The Archaean Eon

Question 79

What do we mean by "The Oxygen Crisis" in relation to the evolution of life on Earth?

A) the extinction of older anaerobic life as oxygen built up in the atmosphere
B) the time period before the development of the ozone layer
C) a period when evolution accelerated so rapidly that there was insufficient oxygen available
D) the destruction of oxygen in the early atmosphere

Question 80

Prior to the Cambrian Period, life consisted of

A) protocells
B) prokaryotes only
C) multicellular organisms
D) single-celled organisms