24: Earth's History and the Diversification of Life Flashcards
Module 4, Lesson 7 (98 cards)
1
Q
List three characteristics shared by all lifeforms on Earth.
A
- They are composed of one or more cells
- They transfer energy to function ad grow
- They encode hereditary information in DNA
2
Q
The geological timescale consists of four…
A
Eons
3
Q
Eons are divided into smaller units called…
A
Eras
4
Q
Eras are divided into smaller subunits called…
A
Periods
5
Q
Periods are divided into smaller subunits called…
A
Epochs and ages
6
Q
Scientists commonly use epochs and/or ages to discuss…
(two)
A
- More recent events
- Very specific periods of deep time
7
Q
What units of time are used on the geological timescale?
A
- MYA (millions of years ago)
- BYA (billions of years ago)
8
Q
When discussing very early events, scientists often use the unit…
A
BYA
9
Q
The scale of timekeeping is called…
A
Deep Time
10
Q
List three common markers used to distinguish units of deep time.
A
- The first appearance of various organisms in the fossil record
- Contintental configurations
- Climate changes
11
Q
The ____ is used to mark major intervals of time in Earth’s history.
A
Geological timescale
12
Q
Prior to isotope dating, scientists determined the boundaries for the divisions of deep time using…
A
Layers of fossils
(strata)
13
Q
The geological timescale is used to discuss…
A
Evolutionary events
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
15
Q
The ____ is invaluable for studying Earth’s history.
A
Fossil record
16
Q
Scientists used ____ to interpret the fossil record before the invention of isotope decay techniques.
A
Relative
17
Q
Relative dating uses a fossil’s placement in strata to…
A
Determine its age relative to other fossils
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.
19
Q
True or false:
Isotope decay rates allow us to determine the absolute numerical age of a fossil.
A
True
20
Q
Carbon-14 is typically used to date materials that are…
A
Less than 50-60,000 years old
21
Q
With isotope decay techniques, different atoms can be used depending on…
A
The relative age of the item being dated
22
Q
Compared to carbon-14, potassium is a better choice for older rocks and fossils because…
A
It decays slower
23
Q
The first evidence of life dates to the…
A
Precambrian
24
Q
Together, the Hadean, Archean, and Proterozoic eons make up the…
A
Precambrian
25
The Precambrian eons preceded the first major...
Diversification of multicellular life
26
How old is the oldest prokaryote fossil?
~3.5 billion years
(Archean eon)
27
# True or false:
The age of the oldest prokaryote fossils tells us the absolute time when life began.
False
28
Based on the age of the oldest prokaryote fossils, we know that prokaryote life began...
At least 3.5 BYA
29
How old are the oldest definitive eukaryote fossils?
~1.5 billion years old
(Proterozoic eon)
30
Multicellular organisms first emerged during the...
Very late Protozeroic eon
31
The ____ marks the start of the Phanerozoic eon.
Cambrian period
32
An extraordinary diversification of multicellular organisms occured during the...
Cambrian period
33
The extraordinary diversification of multicellular organisms during the Cambrian period is referred to as the...
Cambrian explosion
34
Multicellular organisms have existed for around ____% of Earth's history.
12%
35
Birds and mammals have existed for about ____% of Earth's history.
4%
36
Humans have existed for about ____% of Earth's history.
0.2%
37
# True or false:
We know how the earliest organic molecules and organisms came to be.
False
38
List the two major hypotheses about the origin of life on Earth.
1. Life originated on Earth
2. Life came from another planet via a meteorite
39
The hypothesis that life originated on Earth suggests that organic molecules were formed...
When simple elements and compounds were exposed to lightning
40
The ____ simulated conditions in Earth's early atmosphere to see if simple molecules and organic compounds would form.
Miller-Urey experiment
41
# True or false:
The Miller-Urey experiment found that organic compounds were unlikely to have formed in Earth's early atmosphere.
False
About 15% of the "atmospheric" carbon in the experiment was converted into organic molecules or amino acids.
42
Further repetitions of the Miller-Urey experiment have yielded...
| (three)
1. 30 types of carbon compounds
2. Amino acids
3. Adenine
43
List two hypotheses that seek to explain the emergence of metabolic pathways.
1. Primitive lifeforms constructed complex molecules from simple inorganic molecules (autotrophic)
2. Primitive lifeforms acquired complex molecules directly from their environment (heterotrophic)
44
Enzymes had to emerge at some point in order to...
Catalyze metabolic pathways
45
Most modern enzymes are...
Proteins
46
# True or false:
RNA is capable of catalyzing reactions and storing genetic information.
True
47
The ____ states that RNA molecules were the first to catalyze metabolic pathways and the synthesis of peptides.
RNA world hypothesis
48
The first lifeforms were...
Single cells
49
Why were membranes so important in early cells?
| (two)
1. Allowed molecules to be confined to a space
2. Increased the probability of metabolic reactions occuring
50
Early membranes may have been simple and constructed out of...
Fatty acids
51
# True or false:
Evidence suggests that the first living cells had membranes.
True
52
List five major developments that enabled the advent of eukaryotes.
1. Compartmentalization of cells
2. Evolution of the endomembrane system
3. Endosymbiosis
4. Multicellularity
5. Sexual reproduction
53
Why was the compartmentalization of cells important for the development of eukaryotes?
It allowed organisms to grow larger and perform specialized functions
54
Why was the endomembrane system important for the development of eukaryotes?
It is critical for dividing a cell into functional compartments
55
Why was endosymbiosis important for the development of eukaryotes?
It was the process by which eukaryotes obtained energy-producing cells
(mitochondria and chloroplasts)
56
Why was multicellularity important for the development of eukaryotes?
It allowed for diversification
57
# True or false:
Multicellularity is believed to have only evolved once.
False
58
Why was sexual reproduction important for the development of eukaryotes?
It led to increased genetic diversity
59
# True or false:
Only eukaryotes can reproduce sexually.
True
60
Living organisms incorporate ____ into their cells before other isotopes.
Carbon-12
61
The ratio of isotopes in a rock formation is an indicator of whether...
Biological activity occurred there
62
Early organisms used versions of both the Calvin and Krebs cycles for...
Carbon fixation
63
Evidence of carbon fixation has been found in rocks as old as...
3.8 billion years
64
____ are organic molecules that indicate the presence of life.
Biomarkers
65
The carbon isotope ratios in hydrocarbons can be analyzed to determine if they...
Have a biological source
66
The earliest definitive fossil evidence of life has been dated to...
~3.2 BYA
67
It is likely that life on Earth began...
Between 3.8 and 3.5 BYA
68
Why are the oldest microfossils so hard to definitively identify?
| (two)
1. They are small and simple
2. Non-biological processes can produce similar structures
69
The earliest rock formations that have structures believed to be of biological origin have been dated to...
3.8-3.5 BYA
70
____ are structures created by bacteria that trap mineral deposits and are an indicator of biological activity in a rock formation.
Stromatolites
71
Early organisms, like the ones that made the stromatolites likely lived in a...
Very hot environment
72
List four changes to the Earth that have affected evolution.
1. Climate changes
2. Changes in atmospheric composition
3. Continental drift
4. Changes as a result of lifeforms
73
# True or false:
Earth's early atmosphere had very high levels of CO2.
True
74
Earth experienced a two-million-year cooling period due to...
CO2 being removed from the atmosphere via weathering of rocks
75
# True or false:
Earth's temperature has been relatively constant over its history.
False
At times, the Earth's temperature has ranged from >2000 C to -50 C
76
Several periods of ____ have decimated life.
Glaciation
77
____ describes how Earth's crust is comprised of multiple plates that are constantly and gradually shifting.
Plate tectonics
78
Over the course of Earth's history, the continents have merged into ____ multiple times.
Supercontinents
79
How did continental drift affect evolution?
Populations that extended over supercontinents experienced reproductive isolation as the continents drifted apart.
80
During the Cambrian period, the evolution of features characteristic of multicellular organisms led to...
An immense radiation of multicellular organisms
81
# True or false:
The Cambrian Explosion occured both in the oceans and on land.
False
It was confined to the oceans
82
After the Cambrian Explosion, the next major stage of evolution was the...
Move to land
83
Since the terrestrial environment offered new niches and new challenges to overcome...
Many subsequent radiations occurred
84
Our oxygen-rich atmosphere is a result of...
Photosynthesis
85
After the advent of photosynthetic organisms, the change in atmospheric composition experienced a ____ lag.
200-million-year
86
Earth's ozone layer is a result of...
Early interactions between atmospheric oxygen and UV radiation
87
The first major global glaciation period occurred after...
The initial colonization of land by plants
88
The second major global glaciation event is concurrent with...
Vascular plant diversification
89
# True or false:
The evolution of plant life may have contributed to global glaciation events.
True
90
List the three monophyletic domains into which all life on Earth can be grouped.
1. Bacteria
2. Archaea
3. Eukaryota
91
The large number of species in each domain today is a result of...
Rapid diversification caused by the Cambrian Explosion and the subsequent colonization of land
92
# True or false:
New discoveries about evolutionary relationships may lead to a change in the methods used to organize organisms.
False
It may lead to regrouping taxa, but the methods used will remain the same.
93
A species' ____ is the standard way of identifying it to avoid confusion.
Binomial name
94
List the eight taxonomic ranks.
1. Domain
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species
95
# True or false:
The Earth is still actively changing.
True
96
List three areas in which human activity influences the planet.
1. Biodiversity
2. Climate
3. Radioactive materials
97
Historically, sections of the geological timescale have been named based on...
Significant changes in biodiversity and/or climate
98
Some people argue that we are now living in a new epoch called the...
Anthropocene
