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Biology 108 > Topic 6 > Flashcards

Topic 6 Flashcards

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1
Q

What year was the origin of the earth?

A

4.5 bya

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2
Q

how old are the oldest prokaryotes?

A

3.5 mya

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3
Q

how old are the oldest eukaryotes?

A

1.5 bya

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4
Q

the first multicellular organisms arose…

A

1.2 bya

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5
Q

what are the benefits and costs of multicellularity?

A
  • Allows for cellular specialization
    -size
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6
Q

What are the benefits of the size of a cell?

A

Bigger = better
larger means that there is a lower SA to V ratio - it is easier to maintain homeostasis
BUT …. most cells are microscopic … why?

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7
Q

what is the average cell size?

A

1-100 um

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8
Q

why do cells need to be small?

A

smaller= more efficient/faster
more efficient - to obtain raw materials and rid of waste

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9
Q

I thought that bigger = better, so why are cells microscopic? how do we fix this?

A
  • we take a bunch of small and put them together = still efficient and have a small SA to V ratio
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10
Q

what are the benefits of multicellularity?

A

large size
autotrophs
heterotrophs

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11
Q

why is being an autotroph beneficial?

A
  • optimizes conditions for growth and reproduction
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12
Q

why is being a heterotroph beneficial

A
  • more prey species are heterotrophs - less predators
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13
Q

What are the costs of being multicellular?

A
  • high metabolic costs
  • increased generation time
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14
Q

Explain the Colonial model of evolution of multicellular eukaryotes

A
  • multicellular eukaryotes evolved when cells of same species gathered into colonies, the cells differentiated and evolved into multicellular eukaryotes
  • colonies gave rise to division of labor - which allowed distinction among cells
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15
Q

what did colonies do in the colonial model of the evolution of multicellular eukaryotes

A
  • gave rise to the division of labor, leading to structural and functional distinction among cells
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16
Q

how were lineages of algae fungi plants and animals produced?

A
  • multicellularity evolved several times
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17
Q

in what animal phylum are cells not grouped into tissues?

A

porifera
- they also have a non-motile filter feeder with a small # of specialized cells

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18
Q

phylum porifera is at the what level of organization? why?

A

cellular
because they do not join to form tissues

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19
Q

what is bio diversity?

A

the variety of life in the world or in a particular habitat or ecosystem

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20
Q

what two factors determine biodiversity?

A

speciation and extinction
- some say extinction plays higher role

21
Q

Extinctions are naturally balanced by the _______________ of __________. this is why there is still life on earth today

A

formation of new species

22
Q

speciation

A

the birth of a species
- evolution of reproductive isolation within ancestral species - results in 2 descendant species

23
Q

extinction

A

the death of a species
last existing member of a species dies

24
Q

Background extinction

A

a long lasting rate at which taxa become extinct
- it is always slowly happening

25
Q

mass extinction

A

a highly elevated rate of extinction, extends over a relatively short geological interval

26
Q

what is the general geological time scale? from longest to shortest

A

eon - era - period - epoch

27
Q

what are the eons in order of longest ago to most recent?

A

Hadean
Archaean
Proterozoic
phanerozoic

28
Q

describe the Hadean Eon

A

4.6-3.85 bya
the formation of the earth - crust, atmosphere, oceans

29
Q

describe the Archaean eon

A

3.85-2.5 bya
origin of life
evolution of prokaryotes
oxygen begins to accumulate in atmosphere

30
Q

describe the Proterozoic eon

A

2.5bya -542 mya
eukaryotes arise
multicellularity

31
Q

describe the Phanerozoic eon

A

542 mya - present
diversity of plants and animals

32
Q

when was the cambrian explosion?

A

545-488mya

33
Q

what are the order of eras? oldest to most recent

A

Paleozoic, Mesozoic, Cenozoic
- they are all in the phanerozoic eon

34
Q

what is the order of the periods? oldest to most recent

A

Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic, Cretaceous, Paleogene, Neogene, Quaternary

35
Q

how many periods are there?

A

12

36
Q

what is the Cambrian explosion?

A
  • a speciation event
  • all but one of the animal phyla dramatically appear
37
Q

what happened in the cambrian explosion?

A

new modes of moving - swimming, climbing, burrowing
first segmented body plans - a diversity of them too - notochord, external skeletons, appendages

38
Q

what were 3 things that lived during the cambrian period?

A

anomalocaris
trilobits
leanchoilia

39
Q

why did the Cambrian explosion happen? - Name the 3 factors and explain

A
  1. environmental - inc. in oxygen levels = higher metabolism and growth
  2. developmental - evolution of Hox genes that allowed developmental flexibility - lead to minor modifications
  3. Ecological - Predator-prey arms race - change in exoskeleton/locomotory organs
40
Q

what are the 5 major mass Extinctions?

A

Ordovician
Devonian
Permian
Triassic
Cretaceous

41
Q

what was the Carboniferous period like?

A

cold - finite resources

42
Q

what happened in the Ordovician Extinction period?

A

86% species lost

43
Q

What happened in the Devonian Extinction?

A

75% of species lost
- Jawed vertebrates, land vertebrates, etc.

44
Q

What happened in the Permian Extinction?

A

60% all families gone 90% of all marine species

45
Q

What happened in the Triassic Extinction?

A

80% species lost

46
Q

What happened in the Cretaceous Extinction?

A

20% of all families lost
dinosaurs lost - but not birds

47
Q

what is the proposed new epoch called?

A

Anthropocene

48
Q

When did life on earth appear?

A

3.8 bya

Biology 108 (13 decks)

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