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BIOL 108 > Topic 9 > Flashcards

Topic 9 Flashcards

1
Q

What are the features an entity needs to have in order to be considered alive?

A
  1. Organization
  2. Metabolism
  3. Response to stimuli
  4. Homeostasis
  5. Adaptation
  6. Reproduction
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2
Q

What is organization as a feature that an entity needs to have to be considered alive?

A

Structurally composed of one or more cells (multicellular)

  • basic units of life
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3
Q

What is metabolism as a feature that an entity needs to have to be considered alive?

A

A system of management of energy and materials via chemical reactions

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4
Q

What is response to stimuli as a feature that an entity needs to have to be considered alive?

A

Response to stimuli via changes in growth, alteration of chemical reactions, or movement

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5
Q

What is homeostasis as a feature that an entity needs to have to be considered alive?

A

maintenance of some internal chemical and/or thermal consistency, relative to variation outside of the organism

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6
Q

What is adaptation as a feature that an entity needs to have to be considered alive?

A

the ability to change over time in response to the environment.

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7
Q

What is reproduction as a feature that an entity needs to have to be considered alive?

A

the ability to produce new individual organisms

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8
Q

What are viruses?

A

Viruses are infectious parasitic entities that span the boundary between living and non-living.

  • The origins of viruses are unclear because they do not form fossils
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9
Q

Why is it debated whether viruses are alive or not?

A
  • Viruses have nucleic acids (DNA or RNA) that can replicate, mutate, and respond to natural selection
  • But, viruses lack metabolism and homeostasis, and cannot reproduce outside of a host cell
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10
Q

What are the three eons that geologic record is divided into?

A

Archaean, Proterozoic, and Phanerozoic

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11
Q

When was the Phanerozoic eon? What three eras make up the Phanerozoic eon?

A
  • includes the last half billion years and encompasses multicellular eukaryotic life.
  • The three eras are Paleozoic, Mesozoic, and Cenozoic.
  • Major boundaries between geological divisions correspond to mass extinction events in the fossil
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12
Q

What are fossils? What can fossils tell us?

A

Fossils are preserved remains/evidence of organisms that lived in the past.

  • Fossils are associated with sedimentary rock (formed by accumulation of mud, silt, or sand. Layers are called strata).
  • Fossils are used to calibrate phylogenies, record extinct species, and link evolutionary events with geological and environmental changes on Earth.
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13
Q

What is the fossil record?

A

The fossil record provides direct evidence of evolutionary history.

It is also biased and incomplete.

  • Fossilization requires burial in sediment, but sediments accumulate episodically and not continually. Therefore only the hard parts organisms are typically fossilized.
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14
Q

The probability of an organism becoming fossilized increases if:

A
  1. the organism existed for a long time.
  2. The organism was abundant and widespread
  3. Hard rather than soft-bodied
  4. Aquatic rather than terrestrial
  5. Inshore marine rather than offshore marine
  6. Decomposing organisms were absent
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15
Q

What is a cast?

A

A type of fossil record where minerals fill space in sediment where the organism decays after having been buried.

  • Leaves an imprint on what it once was.
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16
Q

What is a replacement (petrified) fossil?

A

A type of fossil record where the organism’s tissues are replaced by minerals. (like a sculpture)

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17
Q

What is a trace fossil?

A

a type of fossil record where the fossil records evidence of behavior

  • tracks, burrows, feces, etc.
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18
Q

What is a preserved fossil?

A

A type of fossil record that retains the original organic matter

  • carbon films, amber, tar or peat, frozen, etc.
  • sub-fossils have a high percent of organic matter.
19
Q

What is relative dating?

A
  • A way of determining the age of fossils, but does not indicate how long ago the fossil was created
  • sedimentary strata reveal the relative ages of fossils
20
Q

What is absolute/radiometric dating?

A
  • a way of determining the age of fossils
  • radioactive decay of isotopes of various elements
21
Q

What does half-life mean in absolute/radiometric dating?

A

It is the time required for 50% of atoms in a given amount of isotope to decay

  • other isotopes are suitable for rock and fossil specimens older than several thousand years
22
Q

What is plate tectonics theory?

A

Considers that Earth’s crust is composed of large plates that have been slowly moving since about 3.4 billion years ago.

  • tectonic plates move slowly through the process of continental drift
23
Q

What is continental drift?

A
  • causes tectonic lates to collide, separate, or slide past each other.
  • interactions between plates cause the formation of mountains, islands, and earthquakes
  • locations of continental land masses have changed over time
24
Q

What did continental drift cause during the Phanerozoic Eon?

A

The formation of the supercontinent Pangaea. This caused:

  1. deepening of ocean basins
  2. reduction in shallow water habitats
  3. colder and drier climate inland
25
Q

What are the consequences of continental drift during the Phanerozoic Eon?

A
  1. Formation of Pangea (approx. 250 million years ago)
  2. Continental drift strongly influenced Earth’s biodiversity (changes to the environment as continents moved north or south)
  3. The distribution of fossils reflects the geologic movement of continents.
26
Q

How many mass extinction events were there? What are the two most notable extinctions called?

A

5 mass extinction events

  • The two most notable mass extinctions were the Permian extinction and the Cretaceous extinction.
27
Q

What was the Permian mass extinction? What caused it?

A

This extinction defines the boundary between the Paleozoic and the Mesozoic eras (252 mya)

  • The earth’s most severe extinction event. Approx. 60% of all biological families were wiped out. Very rapid
  • The best supported hypothesis for the cause of this extinction is catastrophic environmental change due to volcanic activity
28
Q

What was the Cretaceous mass extinction? What caused it?

A

This extinction defines the period between the Mesozoic and Cenozoic eras. About 20% of all families went extinct.

  • The cause was a massive meteorite impact from 66 mya. (we know this because of the presence of iridium in sedimentary rock.
  • dust clouds caused by the impact blocked sunlight, disturbing the global climate.
29
Q

What is the Holocene extinction?

A

The 6th, human-caused mass extinction that is currently ongoing.

  • The Holocene extinction is a result of human activity, driven by population growth and overconsumption of the earth’s natural resources.
30
Q

What are some consequences of mass extinctions?

A
  • The loss of biodiversity alters ecological communities and niches available to organisms
  • adaptive radiation
31
Q

What is adaptive radiation?

A

The rapid evolution of diversely adapted species from an ancestral species.

  • occurs when a change in the environment makes new ecological niches available
  • Mass extinction can lead to adaptive radiation.
32
Q

What can adaptive radiation be followed by?

A
  1. Mass Extinctions
  2. Evolution of novel characteristics
  3. Colonization of new regions
33
Q

Adaptive radiations may follow:

  1. Mass extinctions
A

By eliminating so many species, mass extinctions can pave the way for adaptive radiation.

  • e.x. the disappearance of dinosaurs (except birds) allowed for the expansion of mammals in diversity and size
34
Q

Adaptive radiations may follow:

  1. Evolution of novel characteristics
A

The adaptive radiation of photosynthetic prokaryotes, land plants, insects, and tetrapods were enables by novel adaptations

  • e.x. adaptive radiation of birds following the evolution of powered flight.
35
Q

Adaptive radiations may follow:

  1. Colonization of new regions
A

Adaptive radiation can occur when new organisms colonize new environments with little competition.

  • e.x. Hawaiian plants, textbook example
36
Q

When was earth formed?

A

About 4.6bya.

  • Earth’s surface was inhospitable to life until about 3.8bya.
37
Q

How did life begin on earth?

A

Life likely originated through a set of chemical reactions that gave rise to the molecules of life.

  • the prevailing scientific hypothesis is that the transition from non-living to living entities was not a single event, but an evolutionary process of increasing complexity.
38
Q

What are the hypothesized sequence of stages of the chemical and physical processes that may have produced single cells on earth? (The origin of life)

A
  1. Abiotic synthesis of small organic molecules
  2. Joining of small organic molecules into organic polymers (organic macromolecules)
  3. Packaging of molecules into protocells
  4. Origin of self-replicating molecules
39
Q

What are Prokaryotes? What are the two domains of prokaryotes?

A
  • The oldest fossil evidence of life is of prokaryotes (3.5 - 3.7 bya).
  • Prokaryotes are:
  1. Unicellular
  2. DNA is not contained in the nucleus
  3. Lack of membrane-bound organelles.
  • The two domains of prokaryotes are bacteria ad archaea.
40
Q

What are stromatolites?

A

The oldest known fossils

  • rocks formed by the accumulation of sedimentary layers on prokaryote mats
  • created by the layered prokaryote species in shallow marine environments
41
Q

What was the Great Oxygenation Event (GOE)? How did it start? (slide 42)

A

Earth’s early oceans and atmosphere had almost no free oxygen, and oxygen began accumulating around 2.7 bya.

  • Oceanic photosynthetic prokaryotes (cyanobacteria) used the sun’s energy to fix CO2, producing O2 as a byproduct.
  • initially, O2 produced by cyanobacteria reacted with iron dissolved in oceans. Banded iron formations formed from the precipitate.
  • All soluble iron eventually precipitated and O2 saturation in the oceans was reached. Atmospheric O2 began accumulating.
42
Q

Why did many prokaryotic groups go extinct during the Great Oxygenation Event?

A

Since early prokaryotes evolved in oxygen-free conditions, they used anaerobic metabolism.

  • O2 was toxic to anaerobic prokaryotes.
  • This marked the end of the Archean Eon
43
Q

Did all prokaryotes go extinct during the Great Oxygenation Event? How did they adapt?

A

No!

  • Some prokaryotic groups survived and retained anaerobic metabolism
  • Other prokaryotes evolved anaerobic respiration to adapt to oxygen rich oceans and atmosphere.

BIOL 108 (13 decks)

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