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Life Sciences Grade 10 > History of Life on Earth (from module) > Flashcards

History of Life on Earth (from module) Flashcards

DIAGRAMS IN MODULE/NOTES

1
Q

what 3 changes had an influence on development life on earth

A
  1. Changes in the composition of the atmosphere
  2. changes in climate
  3. geological events
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2
Q

5 characteristics of changes in composition of the atmosphere

A

-3.5 billion years ago: no oxygen
-anaerobic bacteria was first living organisms
-cyanobacteria evolved same time anaerobic bacteria and able remove carbon dioxide from air and release oxygen
-levels of oxygen in atmosphere increased
-new life forms able to evolve

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3
Q

5 characteristics about changes in climate

A

-periods extreme cold followed by warm/very dry periods
-have been 4 ice ages
-ice age occurs when thick layer of ice covers majority earth
-ice forms, ocean levels decrease, land exposed
-ice melts, ocean level rise, lower lying areas of land flood

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4
Q

what is the proof that places were once covered by oceans

A

-bivalves and ammonites on Makhatini flats in KZN
-trilobites in karoo

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5
Q

6 characteristics of geological events

A

-earth divided into tectonic plates that move very slowly
-evidence of tectonic movement includes earthquakes, volcanoes, tsunamis
-movement of tectonic plates cause continental drift
-290mya Earth consisted on land mass called Pangea
-250mya mass separated into 2 land masses: Laurasia and Gondwanaland
-140mya continents as they are today

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6
Q

how do we know that the continents were once joined

A

many examples fossils found separate continents and nowhere else and modern-day distribution of certain animals also suggests some continents were joined before

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7
Q

biogeography

A

study of the distribution of species and ecosystems in geographic space and through geological time

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8
Q

how are eras characterised

A

rock types and fossils

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9
Q

what are the 3 mot recent eras

A

Paleozoic, Mesozoic, Cenozoic

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10
Q

when did the Cambrian period occur

A

545mya-495mya

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11
Q

what animals found Cenozoic era

A

humans and mammals

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12
Q

what species found Mesozoic era

A

dinosaurs, first birds, cycads, modern seed bearing plants

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13
Q

what species found Paleozoic era

A

reptiles, insects, crinoids, cartilage fish, earliest land animals, early bony fish

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14
Q

when did Cambrian explosion start

A

beginning of Paleozoic era

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15
Q

what was life like during Cambrian period

A

-warm climate many warm shallow seas
-no land animals
-large diversification of animals
-multicellular organisms hard exoskeletons common (trilobites)
-many algae, worm-like animals, molluscs, arthropods
-representatives almost all modern-day phyla present

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16
Q

mass extinctions

A

occur over relatively short periods time during which there is a dramatic increase in number of species hat die and disappear

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17
Q

what are the 5 periods of mass extinction

A

Late Ordovician, Late Devonian, End Permian, Late Triassic, Cretaceous-Tertiary Boundary

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18
Q

what causes a mass extinction

A
  1. climate change e.g. glaciation
  2. change in sea level
  3. continental drift
  4. meteorite/asteroid impacts
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19
Q

when was the most recent mass extinction

A

65mya

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20
Q

what are the 2 theories for Cretaceous-Tertiary Boundary mass extinction 65mya

A

meteorite impact theory and vulcanism in India

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21
Q

discuss/explain meteorite impact theory

A

-evidence giant meteorite striking earth (sediment found fossils)
- high iridium concentrations found in layer (iridium only found Earth’s mantle and meteorites/comets)
dust from meteorite impact blocked out sunlight for months, leading to plants death and consequently dinosaurs death
-oxygen levels dropped
-global temperature dropped
-additional carbon dioxide in atmosphere created acid rain

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22
Q

discuss/explain vulcanism in India

A

-evidence immerse volcanic activity found Deccan region
-iridium layer thought been pushed onto earth’s surface by molten rock
-lava released large amounts Sulphur dioxide into atmosphere
-atmosphere and oceans poisoned by falling acid rain
-wide spread fires occurred
-clouds ash blocked sun
-Earth’s temperature cooled
-little/no sunlight, photosynthesis slowed
-plants died, consequently dinosaurs died
-oxygen levels decreased, carbon dioxide level rose
-mass extinction of dinosaurs and other species occurred

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23
Q

what are the possible causes of the mass extinction at end of Permian period 250mya

A

meteorite impact (crate evidence NW Australia) or extended volcanic eruptions (evidence in Siberian traps) - 96% life died

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24
Q

how are humans impacting loss of biodiversity

A

(HIPPO)
-Habitat destruction (roads, buildings, crops, golf courses)
-invasive alien species
-population explosion of humans
-pollution
-over exploitation of natural resources

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25
Q

palaeontology

A

study of fossils

26
Q

fossils

A

remains of living organisms preserved in rocks

27
Q

where are fossils mainly found

A

sedimentary rock

28
Q

how is sedimentary rock formed

A

sediment from rivers or from wind are laid down, thousands years layers pile up and weight presses down on layers below compacting and turning them into sedimentary rock

29
Q

how are fossils formed

A
  1. sediment: animal buried by sediment (volcanic ash/silt) shorty after death. bones protected from rotting by layer of sediment
  2. Layers: mover sediment layer accumulate over years above animal remains and minerals (silica) slowly replace calcium phosphate in bones
  3. Movement: movement of tectonic plates/giant rock slabs that make up Earth’s surface, lifts up sediments and pushes fossils closer to surface
  4. Erosion: from river/rain/wind wears away remaining rock. erosion/people digging expose preserved remains
30
Q

conditions needed for fossilization to occur

A

-animal die near water & covered silt before decomposition
-scavengers must not find/eat body
-sediment needs be acidic and contain no oxygen
-organism must have hard parts (bones, shell, fibers)

31
Q

why is the fossil record incomplete

A

-soft-bodies organisms dont fossilize easily
-ideal conditions are absent
-some fossils difficult identify
-not all fossils have been found yet

32
Q

what are the 4 types of fossil

A
  1. trace
  2. true form
  3. cast
  4. moulds and impressions
33
Q

what is a true form fossil

A

made from actual plant/animal and original features remain intact

34
Q

how are true form fossils preserved

A

hard body parts trapped under layers sand & clay. mineral particles replace hard body tissue. soft body parts decompose before fossilization can occur

35
Q

examples of true form fossils

A

mummies, frozen mammoths, scorpion trapped in amber, Megalodon tooth, skull saber-tooth tiger

36
Q

what is a mould/impression fossil

A

body plant/animal pressed between layers, leaving impression of its shape. surrounding mud & sediment hardens around dead organism and only imprint left after decomposition

37
Q

examples of moulds/impressions

A

trilobite, fern leaf, early fish

38
Q

what is a cast fossil

A

form from moulds. body trapped under layers of sand/clay which harden from rock. body & skeleton dissolve leaving impression on mould. mould filled other materials, forms cast

39
Q

examples of cast fossils

A

cast of brain formed in the cranium

40
Q

what are trace fossils

A

fossils leave records of the behaviors and movements of animals

41
Q

examples of trach fossils

A

footprints, nests, faecal matter, Laetoli footprints, coprolite (dinosaur poop)

42
Q

methods of dating fossils

A
  1. relative dating
  2. radiometric dating
  3. stratigraphic dating
  4. fluorine analysis
43
Q

what is flourine analysis

A

flourine accumulates bones as fossilize. more flourine=older

44
Q

what is stratigraphic dating

A

deeper layers considered older

45
Q

what is relative dating

A

assumes fossils founds same layers are same age and that layers with similar fossils are same age

46
Q

why is relative dating complicated

A

geological factors can cause faulting and tilting of rocks

47
Q

what is radiometric dating

A

relies on decay of radioactive isotopes which happens at predictable rate e.g. Carbon-14 dating, Potassium-argon dating

48
Q

isotope

A

atoms in some chemical elements have different forms which break down over constant rate

49
Q

what are the commonly used elements for radiometric dating

A

argon, uranium, potassium, rubidium - fairly long half life

50
Q

what is deductive reasoning

A

coming to decision/conclusion by using all information gathered e.g. age of fossil, age of surrounding rock, place fossil found

51
Q

what is the most recent species to evolve

A

humans (2.3mya in Africa)

52
Q

what is a transition fossil

A

any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group

53
Q

archaeopteryx

A

transition fossil between reptile and bird

54
Q

thrinaxodon

A

mammal-like reptile found karoo. dates back triassic period (240mya). link between reptile and mammal

55
Q

archaeopteryx reptile features

A

-skull teeth and jaws
-no beak
-3 claws end of bones each wing
-sacrum made 6 vertebrae
-belly ribs
long boy sternum

56
Q

archaeopteryx bird features

A

-feathers
-hollow bones
-wishbone
-3 forward facing toes and backward facing toe

57
Q

what is a living fossil

A

organism remained essentially unchanged from earlier geologic times and whose close relatives are usually extinct

58
Q

example of living fossil

A

Coelacanth, lobed-finned fish thought be extinct

59
Q

world famous fossil sites

A

-cradle humankind
-west coast fossil park in Langebaan
-Kitching Fossil Exploration Centre in Nieu Bethesda

60
Q

when was the taung child found

A

1925 in Taung North West

Life Sciences Grade 10 (10 decks)

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