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BIO1042 > Evolutionary History of Life > Flashcards

Evolutionary History of Life Flashcards

1
Q

fossils

A

the preserved remains of organisms or traces (eg. footprints) or even organic compounds produced by them (chemical fossils)
hard parts fossilise more often

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2
Q

formation of fossils

A

buried in sediment which prevents bacteria decay
built up of sediment squeezes water out
compaction and chemical changes where sediment becomes rock
spaces in bone and wood are filled with minerals (heavier)
fossil moulds (impression) can fill with materials like silica and form fossil casts
trapped in amber
carbonisation: black shale is deposited on the ocean floor (little O2) and preserve soft parts as a thin carbon film on rock

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3
Q

relative dating

A

observing layers of sedimentary rock (stratigraphy)

  • deepest = oldest
  • compare depths
  • often large scale events (volcano) spreads a sedimentary layer for comparison
  • used for geological time scale
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4
Q

absolute dating

A

using radioactivity (half lives) and magnetic reversals

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5
Q

time scale

A

divided into eras and then periods by abrupt changes in the fossil record

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6
Q

precambrian

A

earth origin - evolution of first eukaryotes

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7
Q

palaeozoic

A

diversity of animals (Cambrian explosion) - permian extinction

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8
Q

mesozoic

A

ended with cretaceous extinction

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9
Q

cenozoic

A

to present day

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10
Q

plate tectonics theory

A

crust and part of the upper mantle (together lithosphere) are divided into plates that move, carrying biota with them
about 5cm per year
continental drift

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11
Q

oceanic ridges

A

where lava upwells
new crust of sea floor basalt moves apart on either side of a ridge
as sea floor spreads, continents on lighter (sialic) rocks move away

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12
Q

subduction

A

sea floor descends back into the mantle, forming deep-sea trenches

  • lighter continents remain on the surface
  • no part of the sea floor is older than 200 million years, been subducted
  • trenches mark sites of earthquakes and volcanoes
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13
Q

hot spots

A

fixed points on the mantle where a column of hot basaltic lava rises
- as plates move over them, a chain of volcanic islands may form

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14
Q

types of plate boundaries

A
  • move apart at ridges
  • collide and one is subducted under another at trenches
  • scrape past each other, causing deformations and faults
  • collisions can create mountain belts
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15
Q

ancient positions of continents

A
  • study past positions - rock magnetism, hot spots and magnetic reversals
  • erosion and subduction destroy evidence (more than 20% of precambrian rocks lost, 90% of history)
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16
Q

rodinia

A

giant continent formed 1.2 billion years ago

750-800 million years ago it drifted to form 8 continents

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17
Q

super continents

A

500 mill ya: most landmasses at equator. Australia part of Gondwana and Europe part of Baltica
northern landmasses formed Laurasia and Gondwana went south
250 million years ago lausasia and Gondwana formed Pangea (inner area far from sea and very arid)
jurassic period: Gondwana split again and broke up 130 million years ago

18
Q

precambrian era

  • cherts and stromatolites
  • chlorophyll
  • organisms
A

archaean eon and proterozoic eon
cherts: fossils found in black chert (gels of silica) that precipitated on the ancient sea floor - oldest fossils are 3.3-3.5 billion year old cherts in WA (look like bacteria and cyanobacteria

stromatolites: fossils of concentrically layered rock - sediments trapped between layers of cyanobacteria (3.3-3.5 bill ya)

pristine and phytane (products of chlorophyll) and photosynthetic organisms

ironstones from 1.8-2.3 bill ya indicate oxygen became plentiful

prokaryotes and eukaryotes like green algae appear

19
Q

ediacaran fauna: multicellular organisms

A

soft bodies organisms such as marine worms, jellyfish and anemone found as tracks, burrows and impressions 540-590 mill ya
all continents
short time before disappearing before shelly invertebrates in Cambrian
multicellular evolved in precambrian!

20
Q

palaeozoic life: ancient life

A

251-542 mill ya
age of fishes and rapid evolution
mass extinction with loss of shallow seas

marine life:

  • phytoplankton, zooplankton, trilobites (anthropods)
  • shallow seas in ordovician - corals and molluscs
  • jawless fish (ostracoderms) were the first vertebrates
  • fleshy finned fish were related to first 4 legged vertebrates on land

terrestrial life:

  • silurian (410 mill ya) earliest evidence of life on land
  • amphibians in late denovian
  • by end of palaeozoic, every major plant group had appeared (except flowering plants)
21
Q

mesozoic life: age of reptiles

A

dinosaurs reigned but went extinct in cretaceous
dinosaur descendants, therapsids, gave rise to mammals
thecodonts were first bipedal
land habitats became available and mammals expanded (triassic)
cretaceous sudden radiation of flowering plants

22
Q

cenozoic life: the beginning of modern life

A

65 mill ya to present
mammals and flowering plants become abundant
fossils of lineages related to humans date back at least 6 million years

23
Q

biogeographic region

A

regions inhabited by unique forms of life

24
Q

boreal region

A

northern fir forests (holarctic, palaearctic, nearctic)

25
Q

palaeotropical regions

A

plants in africa, India and SE africa and animals

Ethiopian oriental

26
Q

neotropical

A

South America, lower Central America

27
Q

australian region

A

australia, PNG, new Caledonia and NZ

28
Q

marine biogeographic zones

A

shallow water (shelf) and open ocean (pelagic)
continental shelf most diverse in tropics
bipolar distribution: one species living in arctic and the other in Antarctica
pelagic realm: planktonic organisms near surface, currents seperate species

29
Q

prokaryotes diversification

A

found in rocks 3.77-4.28 bya
only inhabitants for 3 billion years - developed RNA, mitochondria, chloroplasts (oxygen was a poisonous waste product) and genes

30
Q

singe celled eukaryotes

A

evolved from archael common ancestor - first eukaryotic common ancestor (resembled archaea)
1 billion ya FECA engulfed bacteria and formed a symbiotic relationship (ATP for Achaea and nutrients for bacteria). codependence resulted and genes were exchanged (mitochondria gets less). mitochondria gets cristae (increased SA)

31
Q

evidence of endosymbiosis

A 
double membrane (phospholipids are different on each layer)
DNA - mitochondria has circular DNA similar to prokaryotes
32
Q

cyanobacteria became

A

chloroplasts

33
Q

multicellular eucaryotes

A

cells stick together
cells communicate
participate in a network of genetic interactions that regulate differentiation and division
cells can become specialised and can exceed size limits placed by diffusion, longer lifespan (cells die, not the organism)

34
Q

earliest animals

A

dickinsonia (precursor to Cambrian animals) are small, oval, soft bodies marine organisms (571-541 mya)

35
Q

diversification of animals

A

Cambrian explosion 13-25 mya
not many soft bodies fossils
molecular clocks: assuming DNA substitution rate is constant to determine age

36
Q

colonisation of land

A

450 mya, plants and animals moved onto land (algae on soil)
algae already had genes needed to detect and interact with beneficial fungi (to get water) - allowed them to survive and evolve
animals like tiktaalik developed fins like legs and could move on land

37
Q

oxygen and evolution

A

increases oxygen during precambrian period
evolution of large vascular plants increased oxygen (coal deposits and wildfires are evidence)
conquest of land by animals happened in two phases of high O2 concentration
oxygen forced evolution of animals (body size increased - gigantism - increased O2 diffusion especially across egg shell = big
decreased O2 led to oxygen

38
Q

being the right size

A

small animals have resistance to falling
small organisms can walk on water
large animals pump blood further so larger blood pressure and tougher blood vessels
small organisms can diffuse when the limit is reached, SA is increased by gills and lungs

39
Q

calculating SA

A

volume of sphere: 4/3pi r^3
SA of sphere: A = 4pi r^2
SA/volume

40
Q

small

A

increased SA/V

efficiency of diffusion increases

41
Q

calculating diffusion of oxygen

A

oxygen moves down the concentration gradient at a rate of J = D x (P0 - Pi)/T
J - rate of O2 movement
D - diffusion coefficient for environment
P0 - partial oxygen pressure outside cell
Pi - partial pressure inside
T - distance between two sides

42
Q

when did oxygen spike?

A

410 mya, 290-300 mya

BIO1042 (12 decks)

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