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BIO 1306 Spring 2025 > Chapter 25 - The History of Life on Earth > Flashcards

Chapter 25 - The History of Life on Earth Flashcards

1
Q

The _______ shows macroevolutionary changes over large time scales

A

…fossil record…

Ex:
1. emergence of terrestrial vertebrates
2. the impact of mass extinctions
3. the origin of key adaptations (like flight)

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2
Q

[Conditions on early Earth made the origin of life possible]
Chemical & physical processes could produce ______ thru 4 stages

A

…simple cells…

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3
Q

4 stages to produce simple cells:

A
  1. Abiotic(lifeless) synthesis of small organic molecules (ex: oxygen, carbon, nitrogen)
  2. Joining of small molecules into macromolecules
  3. Package of molecules into protocells (cell prototype)
  4. Origin of self-replicating molecules
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4
Q

Earth formed abt ____ billion yrs ago thru collisions w/ rocks and ice & vaporized water

A

4.6

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5
Q

_______ (reanalysis in 2008) results showed that amino acids were formed under conditions simulating volcanic eruption

A

Miller’s experiment…

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6
Q

The environment near alkaline vents were likely more suitable for ______.

A

the origin of life

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7
Q

Organic compounds in ___________ (areas on the seafloor where hot water and minerals gush from Earth’s interior into the ocean)

A

deep-sea hydrothermal vents

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8
Q

Alkaline/hydrothermal vents release water w/ high pH (9-11) and warm water (40-90 C)

A

True

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9
Q

Meteorites could also have been a source of ____

A

…organic molecules

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10
Q

Fragments of the 4.5 billion yr old _____ meteorite contain amino acids, lipids, simple sugars, and nitrogenous bases

A

…Murchison…

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11
Q

Protocells?

A

self-organized collection of lipids

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12
Q

Protocells may have formed from…

A

…fluid-filled vesicles with a membrane-like structure

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13
Q

_____ are key properties of life and may have appeared together in protocells

A

Replication and metabolism…

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14
Q

In water, lipids and other organic molecules can
spontaneously form vesicles with a…

A

…lipid bilayer

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15
Q

Vesicles can exhibit some of the properties of life like:

A

Simple growth, reproduction, metabolism, maintenance of internal environment

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16
Q

The first genetic material was likely ____, not ____

A

RNA, DNA

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17
Q

RNA plays a central role in…

A

…protein synthesis

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18
Q

The RNA molecule w/ the greatest _____ ability leaves the most descendant molecules

A

…self-replication…

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19
Q

Protocells could form on early Earth from ____ that grew, split, and passed RNA to their “daughters”

A

…vesicles…

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20
Q

______ could act on protocells that formed from vesicles, making more successful forms over generations

A

Natural selection…

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21
Q

RNA could have provided the template for the assembly of…

A

…DNA nucleotides

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22
Q

The fossil record is based on the accumulator of fossils in sedimentary rock layers, called…

A

…strata

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23
Q

The study of fossils is used to establish the geologic record:

A

a standard time scale dividing Earth’s history into four ages 9eon) and further subdivisions

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24
Q

The geologic record is divided into the…

A

…Hadean, Archaean, Proterozoic, and Phanerozoic eons

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25
The Phanerozoic eon includes the last half billion years is divided into 3 eras:
Paleozoic, Mesozoic, and Cenozoic
26
Major boundaries btwn eras correspond to _____ in the fossil record
...major extinction events...
27
The first single-celled organisms/oldest known fossils
stromatolites
28
What are stromatolites?
Layered rocks formed when prokaryotes bind thin films of sediment together
29
Fossilized stromatolites from ______ yrs ago are the earliest evidence of life on Earth
...3.5 billion...
30
Prokaryotes were Earth's sole inhabitants for more than...
...1.5 billion yrs
31
Oxygen gradually accumulated in the atmosphere abt 2.7-2.4 billion yrs ago & shot up rapidly btwn 1-10% of its present level (referred to as the ______)
oxygen revolution
32
The oxygen revolution caused the _____ of many prokaryotic groups. Some groups survived in anaerobic environments & others adapted to using cellular respiration to harvest energy.
extinction
33
The oldest eukaryote fossils are from single-celled organisms that lived _____ yrs ago
1.8 billion
34
Eukaryotes likely originated by ______ when a prokaryotic cell (archaea) engulfed a small cell that evolved into a mitochondrion and plastids (i.e., chloroplast)
endosymbiosis
35
Both mitochondria and plastids are thought to have descended from...
...bacterial cells
36
All eukaryotic cells have mitochondria but not all have ____ (chloroplasts & related organelles)
plastids
37
Cambrian explosion
The sudden appearance of fossils resembling modern animal phyla (535-525 million yrs ago)
38
Animal phyla during cambrian explosion:
Sponges, cnidarians, and molluscs
39
[Paleozoic, Cambrian] First evidence of predator-prey reactions
Adaptations for predation, including large bodies & claws appeared New defense adaptations, such as sharp spines & body armor appeared in prey species
40
_______ began to colonize land about 500 million years ago
Fungi, plants, and animals...
41
[Colonization of land] Plants evolved adaptations to...
...reproduce on land and avoid dehydration
42
[Colonization of land] Arthropods & tetrapods:
The most widespread & diverse land animals -Arthros among 1st animals to colonize land abt 450 million yrs ago -Tetras evolved from lobe-finned fishes around 365 million yrs ago
43
The rise & fall of groups of organisms reflect difference in _______
speciation & extinction rates
44
Speciation & extinction are affected by processes including...
plate tectonics, mass extinction, and adaptive radiation
45
The landmasses of Earth formed a supercontinent ___ times
3
46
Formation of the supercontinent Pangaea about 250 million years ago had many effects:
-Deepening of ocean basins -most shallow-water habitat destroyed -colder & drier climate inland
47
[Consequences of continental drift] Organisms must adapt, move to a new location, or face extinction as the climate changes in response to...
...continents moving toward or away from the equator
48
Mass extinctions are triggered by disruptive...
...global change
49
The Permian extinction (___ million years ago) divides the Paleozoic from the Mesozoic era
252
50
The permian extinction was caused by _____. The earth warmed 6 degrees, oceans acidified, bacteria bloomed, decomposition caused low oxygen levels, anaerobics bloomed, 96% of marine life perished
extreme volcanic activity
51
Cretaceous mass extinction happened...
...66 million years ago
52
Events of Cretaceous mass extinction:
->50% of marine species, many terrestrial plants & animals, and ALL dinosaurs (except birds) went extinct -Debris blocked sun for months, causing drop in global temp -Chicxulub crater off the coast of mexico is evidence of massive meteorite collision that dates to the same time
53
[Consequences of Mass Extinctions] It typically takes ____ million years for diversity to recover following a mass extinction; in some cases up to 100 million years
5–10
54
Mass extinctions can change the _____ found in ecological communities
types of organisms
55
After the Permian and Cretaceous mass extinctions, the percent of marine predators ____
increased
56
[Consequences of mass extinctions] Mass extinctions can also eliminate lineages with novel and ____ features
advantageous (ex: shell-drilling gastropods were lost in the extinction at the end of the Triassic and did not reappear for 120 million years)
57
By eliminating so many species, mass extinctions pave the way for _____, and the proliferation of new groups of organisms
adaptive radiations
58
Major changes in body form can result from changes in the _____ of developmental genes
sequences and regulation
59
Studying ______ can provide insight into large-scale evolutionary change
genetic mechanisms of change
60
Genes that program development control ______ in an organism’s form as it develops to adulthood
the rate, timing, and spatial pattern of changes
61
What is heterochrony?
It alters the relative timing of reproductive to nonreproductive in development (ex: paedomorphosis)
62
What is paedomorphosis?
neotony/juvenile characteristics retained despite being fully mature adult
63
Changes in genes that control the placement and organization of body parts can drive ____
evolution
64
what are Homeotic genes/Hox genes?
master regulatory genes that determine where an organism’s features will develop.
65
Evolution is not goal oriented (T/F)
True
66

BIO 1306 Spring 2025 (5 decks)

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