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BIOL 1105 > 24: Earth's History and the Diversification of Life > Flashcards

24: Earth's History and the Diversification of Life Flashcards

Module 4, Lesson 7

1
Q

List three characteristics shared by all lifeforms on Earth.

A
  1. They are composed of one or more cells
  2. They transfer energy to function ad grow
  3. They encode hereditary information in DNA
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2
Q

The geological timescale consists of four…

A

Eons

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3
Q

Eons are divided into smaller units called…

A

Eras

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4
Q

Eras are divided into smaller subunits called…

A

Periods

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5
Q

Periods are divided into smaller subunits called…

A

Epochs and ages

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6
Q

Scientists commonly use epochs and/or ages to discuss…

(two)

A
  1. More recent events
  2. Very specific periods of deep time
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7
Q

What units of time are used on the geological timescale?

A
  1. MYA (millions of years ago)
  2. BYA (billions of years ago)
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8
Q

When discussing very early events, scientists often use the unit…

A

BYA

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9
Q

The scale of timekeeping is called…

A

Deep Time

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10
Q

List three common markers used to distinguish units of deep time.

A
  1. The first appearance of various organisms in the fossil record
  2. Contintental configurations
  3. Climate changes
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11
Q

The ____ is used to mark major intervals of time in Earth’s history.

A

Geological timescale

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12
Q

Prior to isotope dating, scientists determined the boundaries for the divisions of deep time using…

A

Layers of fossils
(strata)

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13
Q

The geological timescale is used to discuss…

A

Evolutionary events

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14
Q

In order to make it easier to visualize the timeframe of evolutionary changes, scientists may include ____ with phylogenies.

A

A range of epochs

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15
Q

The ____ is invaluable for studying Earth’s history.

A

Fossil record

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16
Q

Scientists used ____ to interpret the fossil record before the invention of isotope decay techniques.

A

Relative

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17
Q

Relative dating uses a fossil’s placement in strata to…

A

Determine its age relative to other fossils

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18
Q

True or false:

Relative dating provides absolute numerical values for the age of a fossil.

A

False

Relative dating only provides insight into the order in which species evolved.

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19
Q

True or false:

Isotope decay rates allow us to determine the absolute numerical age of a fossil.

A

True

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20
Q

Carbon-14 is typically used to date materials that are…

A

Less than 50-60,000 years old

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21
Q

With isotope decay techniques, different atoms can be used depending on…

A

The relative age of the item being dated

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22
Q

Compared to carbon-14, potassium is a better choice for older rocks and fossils because…

A

It decays slower

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23
Q

The first evidence of life dates to the…

A

Precambrian

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24
Q

Together, the Hadean, Archean, and Proterozoic eons make up the…

A

Precambrian

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25
Q

The Precambrian eons preceded the first major…

A

Diversification of multicellular life

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26
Q

How old is the oldest prokaryote fossil?

A

~3.5 billion years
(Archean eon)

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27
Q

True or false:

The age of the oldest prokaryote fossils tells us the absolute time when life began.

A

False

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28
Q

Based on the age of the oldest prokaryote fossils, we know that prokaryote life began…

A

At least 3.5 BYA

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29
Q

How old are the oldest definitive eukaryote fossils?

A

~1.5 billion years old
(Proterozoic eon)

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30
Q

Multicellular organisms first emerged during the…

A

Very late Protozeroic eon

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31
Q

The ____ marks the start of the Phanerozoic eon.

A

Cambrian period

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32
Q

An extraordinary diversification of multicellular organisms occured during the…

A

Cambrian period

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33
Q

The extraordinary diversification of multicellular organisms during the Cambrian period is referred to as the…

A

Cambrian explosion

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34
Q

Multicellular organisms have existed for around ____% of Earth’s history.

A

12%

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35
Q

Birds and mammals have existed for about ____% of Earth’s history.

A

4%

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36
Q

Humans have existed for about ____% of Earth’s history.

A

0.2%

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37
Q

True or false:

We know how the earliest organic molecules and organisms came to be.

A

False

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38
Q

List the two major hypotheses about the origin of life on Earth.

A
  1. Life originated on Earth
  2. Life came from another planet via a meteorite
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39
Q

The hypothesis that life originated on Earth suggests that organic molecules were formed…

A

When simple elements and compounds were exposed to lightning

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40
Q

The ____ simulated conditions in Earth’s early atmosphere to see if simple molecules and organic compounds would form.

A

Miller-Urey experiment

41
Q

True or false:

The Miller-Urey experiment found that organic compounds were unlikely to have formed in Earth’s early atmosphere.

A

False

About 15% of the “atmospheric” carbon in the experiment was converted into organic molecules or amino acids.

42
Q

Further repetitions of the Miller-Urey experiment have yielded…

(three)

A
  1. 30 types of carbon compounds
  2. Amino acids
  3. Adenine
43
Q

List two hypotheses that seek to explain the emergence of metabolic pathways.

A
  1. Primitive lifeforms constructed complex molecules from simple inorganic molecules (autotrophic)
  2. Primitive lifeforms acquired complex molecules directly from their environment (heterotrophic)
44
Q

Enzymes had to emerge at some point in order to…

A

Catalyze metabolic pathways

45
Q

Most modern enzymes are…

A

Proteins

46
Q

True or false:

RNA is capable of catalyzing reactions and storing genetic information.

A

True

47
Q

The ____ states that RNA molecules were the first to catalyze metabolic pathways and the synthesis of peptides.

A

RNA world hypothesis

48
Q

The first lifeforms were…

A

Single cells

49
Q

Why were membranes so important in early cells?

(two)

A
  1. Allowed molecules to be confined to a space
  2. Increased the probability of metabolic reactions occuring
50
Q

Early membranes may have been simple and constructed out of…

A

Fatty acids

51
Q

True or false:

Evidence suggests that the first living cells had membranes.

A

True

52
Q

List five major developments that enabled the advent of eukaryotes.

A
  1. Compartmentalization of cells
  2. Evolution of the endomembrane system
  3. Endosymbiosis
  4. Multicellularity
  5. Sexual reproduction
53
Q

Why was the compartmentalization of cells important for the development of eukaryotes?

A

It allowed organisms to grow larger and perform specialized functions

54
Q

Why was the endomembrane system important for the development of eukaryotes?

A

It is critical for dividing a cell into functional compartments

55
Q

Why was endosymbiosis important for the development of eukaryotes?

A

It was the process by which eukaryotes obtained energy-producing cells
(mitochondria and chloroplasts)

56
Q

Why was multicellularity important for the development of eukaryotes?

A

It allowed for diversification

57
Q

True or false:

Multicellularity is believed to have only evolved once.

A

False

58
Q

Why was sexual reproduction important for the development of eukaryotes?

A

It led to increased genetic diversity

59
Q

True or false:

Only eukaryotes can reproduce sexually.

A

True

60
Q

Living organisms incorporate ____ into their cells before other isotopes.

A

Carbon-12

61
Q

The ratio of isotopes in a rock formation is an indicator of whether…

A

Biological activity occurred there

62
Q

Early organisms used versions of both the Calvin and Krebs cycles for…

A

Carbon fixation

63
Q

Evidence of carbon fixation has been found in rocks as old as…

A

3.8 billion years

64
Q

____ are organic molecules that indicate the presence of life.

A

Biomarkers

65
Q

The carbon isotope ratios in hydrocarbons can be analyzed to determine if they…

A

Have a biological source

66
Q

The earliest definitive fossil evidence of life has been dated to…

A

~3.2 BYA

67
Q

It is likely that life on Earth began…

A

Between 3.8 and 3.5 BYA

68
Q

Why are the oldest microfossils so hard to definitively identify?

(two)

A
  1. They are small and simple
  2. Non-biological processes can produce similar structures
69
Q

The earliest rock formations that have structures believed to be of biological origin have been dated to…

A

3.8-3.5 BYA

70
Q

____ are structures created by bacteria that trap mineral deposits and are an indicator of biological activity in a rock formation.

A

Stromatolites

71
Q

Early organisms, like the ones that made the stromatolites likely lived in a…

A

Very hot environment

72
Q

List four changes to the Earth that have affected evolution.

A
  1. Climate changes
  2. Changes in atmospheric composition
  3. Continental drift
  4. Changes as a result of lifeforms
73
Q

True or false:

Earth’s early atmosphere had very high levels of CO2.

A

True

74
Q

Earth experienced a two-million-year cooling period due to…

A

CO2 being removed from the atmosphere via weathering of rocks

75
Q

True or false:

Earth’s temperature has been relatively constant over its history.

A

False

At times, the Earth’s temperature has ranged from >2000 C to -50 C

76
Q

Several periods of ____ have decimated life.

A

Glaciation

77
Q

____ describes how Earth’s crust is comprised of multiple plates that are constantly and gradually shifting.

A

Plate tectonics

78
Q

Over the course of Earth’s history, the continents have merged into ____ multiple times.

A

Supercontinents

79
Q

How did continental drift affect evolution?

A

Populations that extended over supercontinents experienced reproductive isolation as the continents drifted apart.

80
Q

During the Cambrian period, the evolution of features characteristic of multicellular organisms led to…

A

An immense radiation of multicellular organisms

81
Q

True or false:

The Cambrian Explosion occured both in the oceans and on land.

A

False

It was confined to the oceans

82
Q

After the Cambrian Explosion, the next major stage of evolution was the…

A

Move to land

83
Q

Since the terrestrial environment offered new niches and new challenges to overcome…

A

Many subsequent radiations occurred

84
Q

Our oxygen-rich atmosphere is a result of…

A

Photosynthesis

85
Q

After the advent of photosynthetic organisms, the change in atmospheric composition experienced a ____ lag.

A

200-million-year

86
Q

Earth’s ozone layer is a result of…

A

Early interactions between atmospheric oxygen and UV radiation

87
Q

The first major global glaciation period occurred after…

A

The initial colonization of land by plants

88
Q

The second major global glaciation event is concurrent with…

A

Vascular plant diversification

89
Q

True or false:

The evolution of plant life may have contributed to global glaciation events.

A

True

90
Q

List the three monophyletic domains into which all life on Earth can be grouped.

A
  1. Bacteria
  2. Archaea
  3. Eukaryota
91
Q

The large number of species in each domain today is a result of…

A

Rapid diversification caused by the Cambrian Explosion and the subsequent colonization of land

92
Q

True or false:

New discoveries about evolutionary relationships may lead to a change in the methods used to organize organisms.

A

False

It may lead to regrouping taxa, but the methods used will remain the same.

93
Q

A species’ ____ is the standard way of identifying it to avoid confusion.

A

Binomial name

94
Q

List the eight taxonomic ranks.

A
  1. Domain
  2. Kingdom
  3. Phylum
  4. Class
  5. Order
  6. Family
  7. Genus
  8. Species
95
Q

True or false:

The Earth is still actively changing.

A

True

96
Q

List three areas in which human activity influences the planet.

A
  1. Biodiversity
  2. Climate
  3. Radioactive materials
97
Q

Historically, sections of the geological timescale have been named based on…

A

Significant changes in biodiversity and/or climate

98
Q

Some people argue that we are now living in a new epoch called the…

A

Anthropocene

BIOL 1105 (26 decks)

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