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Evolutionary biology, LEC 141 > Brief history of life on Earth, Lecture 3 > Flashcards

Brief history of life on Earth, Lecture 3 Flashcards

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1
Q

Three domains of life

A

Bacteria, eukaryotes, archaea

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2
Q

Six kingdoms

A
  1. Archeabacteria
  2. Eubacteria
  3. Protists
  4. fungi
  5. plantae
  6. animalia
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3
Q

Archaaebacteria

six kindgoms of life

A

Prokaryotes that lack a peptido-glycan cell wall, eg: extreme halophiles, thermophiles and methanogens.

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4
Q

Eubacteria

six kindgoms of life

A

Prokaryotes with a peptidoglycan cell wall, eg: cyanobacteria, soil bacteria, nitrogen-fixing bacteria and pathogenic bacteria

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5
Q

Protists

six kindgoms of life

A

Eukaryotic, primarily unicellular organisms, heterotrophic or photosynthetic organisms

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6
Q

Fungi

six kindgoms of life

A

Heterotrophic, eukaryotic, chitin cell walls, mostly multicellular, usually non-motile

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7
Q

Plantae

six kindgoms of life

A

eukaryotic, multicellular, photosynthetic, non-motile

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8
Q

Animalia

six kindgoms of life

A

Eukaryotic, heterotrophic, multicellular, motile

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9
Q

Early Earth

A

4.5 billion years old

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10
Q

Characteristics of early earth

A

hostile, hot environment

reducing atmosphere - enabled formation of carbon rich compounds

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11
Q

When did life begin?

A

3.8 billion years ago

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12
Q

Earliest fossils

A
  • are of prokaryotes, 3.5 billion years ago,
  • simple structure, no nucleus and few internal structures
  • dominant between 3.5-2 billion years ago
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13
Q

Stromatolites

A

precambrian ‘colonies’ of cyanobacteria

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14
Q

Photosynthesis

A

oxygen production

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15
Q

Which two main evolutionary branches do prokaryotes comprise?

A

bacteria and archaea

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16
Q

Which groups are included in the archaea?

3

A

methane producers, thermophiles and halophiles

these are found in very hostile anaerobic environments

17
Q

When did cyanobacteria evolve?

A

around 3.5 billion years ago

18
Q

Cyanobacteria

A

oxygen generating photosynthetic algae

19
Q

Role of cyanobacteria in early earth?

A

raised atmosphere oxygen levels
enabled the ozone layer to form
protected the earth from UV radiation

20
Q

Characteristics of eukaryotes

A

nucleus, chloroplasts, mitochondria

21
Q

The origin of eukaryotes

5

A
  • ancestral prokaryote
  • infoldings of plasma membrane
  • engulfing of aerobic heterotrophic prokaryote
  • engulfing of photosynthetic prokaryote
  • endosymbiotic relationships between bacteria
22
Q

Multicellular eukaryotes

6

A
  • evolved from single-celled eukaryotes living in association with each other
  • development of specialised cells
  • most are aerobic
  • sexual reproduction was generally well developed
  • the fusion of gametes enabled genetic recombination
  • sex generates variation, enabling faster evolution
23
Q

When was there an explosion in eukaryotic diversity?

A

at the end of the ice age, early cambrian period, about 570 million years ago

24
Q

When was land colonised by plants, animals and fungi?

A

about 500 million years ago

25
Q

When were most of the orders of modern mammals, inc. the primates, established?

A

50-60 MYA

26
Q

When did the human lineage diverge from other primates?

A

5 - 6.5 mya

27
Q

Which events shape evolution?

A

mass extinctions

28
Q

Impact of extinction events

4

A
  • create ‘ecological space’
  • removes organisms occupying some niches
  • the survivors descendants could evolve into those spaces with fewer constraints
  • adaptive radiation may occur after mass extinctions or when new opportunities arise, eg: new islands
29
Q

Adaptive radiation meaning

A

A process in which organisms diversify rapidly from an ancestral species into a multitude of new forms

30
Q

When does adaptive radiation often occur?w

A

when a change in the environment makes new resources available

31
Q

Example of adaptive radiation
Dawin’s finches
5

A
  1. ancestral finches arrive on island
  2. lack of small birds so no competition for food etc.
  3. finches diverged to occupy different habitats
  4. some evolved into different species
  5. finches with different beaks and feeding habits

Evolutionary biology, LEC 141 (11 decks)

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