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Life Sciences > History Of Life On Earth > Flashcards

History Of Life On Earth Flashcards

1
Q

Life exists in..

A

A huge array of FORMS and MODES of life.

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2
Q

Enormous biodiversity exists in Earth:

*endemism in Southern Africa

A

Large variety:
1. Species
2. Different ecosystems
3. Genetic differences

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3
Q

Endemism:

A

Indigenous but only found in 1 geographical space / area in country:

*hyper specific indigenous

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4
Q

Indigenous:

A

Comes from a specific country (native and originally found there)

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5
Q

Biodiversity:

A

The variety of organisms that can be found on earth as well as the interaction between them.

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6
Q

What is the first life form, that modern life extended from?

A

First bacteria: CYANOBACTERIA

(Blue/ green) : made photosynthesis possible
(First autotroph)

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7
Q

What are the changes in life forms related to?

A

*Climate change
*Movement of continents and oceans over evolutionary time

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8
Q

History of life on earth

A

The study of how organisms originated and diversified over time on our plsnet

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9
Q

Evidence to formulate history of life on earth:

A
  1. Geological events
  2. Geological rock dating
  3. Biogeography
  4. Fossil dating
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10
Q

Study of fossils:

A

Palaeontology

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11
Q

What is a common ancestor?

A

The original organism from which all life forms diverged and are then related to

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12
Q

Common ancestor for all life on earth:

A

ANAEROBIC BACTERIA
(Oxygen not required for life processes)

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13
Q

6 most important geological events that influences living things over time:

A
  1. Atmospheric oxygen content changes
  2. Continental drift
  3. Plate tectonics
  4. Volcanic activity
  5. Ice ages
  6. Meteorite / asteroid impacts
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14
Q

Changes in the composition of the atmosphere!

A

Increases in levels of oxygen
CYANOBACTERIA

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15
Q

Development of photosynthesising bacteria created current atmospheric composition:

A

*Cyanobacteria bacteria used CO2 in air and gave off O2 as byproduct of photosynthesis.
*Concentration of O2 starting increasing.
*As number of Cyanobacteria increased : CO2 concentration decreased.

*levels of N2 (nitrogen) in atmosphere increased.
- N2 in sea water used by Cyanobacteria to make PROTEINS

Increased O2 and increased UV exposure = OZONE LAYER around planet

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16
Q

What is the green house effect?

A

A good process whereby the Earth is kept warm

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17
Q

Most common greenhouse gases:

A

Methane
CO2
Nitrous oxide

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18
Q

Effect of too much greenhouse gases:

A

Leads to:
1. Global warming
2. Green house effect

(Harming earth)

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19
Q

What does the enhanced greenhouse effect lead to:

A

Climate change & Global warming
- disrupts ecosystems and decreases biodiversity

(currently: 6th maths extinction)

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20
Q

Ice ages:

A

*Long periods of extremely low temperatures leading to Earth covered in glaciers and ice sheets.

  • sea levels were low: water trapped in glaciers
  • habitats of marine species decreased

-species who were not (FIT) for dry conditions : did not survive

*once temps increased, ice caps melted = increase in sea levels

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21
Q

Survival of the fittest:

A

NATURAL SELECTION

  • affects biodiversity and changes composition of ecosystems : affecting energy flow of organisms.
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22
Q

Geological events : continental drift

A
  1. Earth’s continents were once joined as 1 supercontinent : PANGAEA
  2. Drifted apart (plate tectonics) : LAURASIA (N) & GONDWANALAND (S)
  3. 7 continents
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23
Q

plate tectonics refers to:

A

Movement of tectonic plates under Earth’s crust.

*when join/ rub: EARTHQUAKES OR VOLCANIC ACTIVITY occur

(As tectonic plates move: continents move)

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24
Q

Change in animal distribution influenced by:

A

Continental drift

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25
Q

Define: Biogeography

A

The study of the distribution of organisms on various continents over time.

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26
Q

Changes in sea level: RISE AND FALL OF LAND

A

As sea levels change: amount of available land changes

*Decrease: glaciation
*Increase: melting glaciers

Evidence supporting:
-Sahara: whale fossils
-Karoo: trilobites

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27
Q

Why do volcanic eruptions take place?

A
  1. Continental drift
  2. Large meteorites & comets hitting Earth surface
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28
Q

Impact of volcanic activity:

A
  • Release ash and dust: blocks out the sun — cooling down of earth — glaciers — decrease sea levels
29
Q

Effect on photosynthesising plants:

A

*Photosynthesis CANT take place : light unavailable to plants

  1. Increased : CO2 / decreased : O2
  2. Scarcity of food : life died off
  3. Mass extinction
  4. Dust settled — increased CO2: enhanced greenhouse effect
  5. Warming earth : melting ice caps
  6. Sea levels rose
  7. Photosynthesis could OCCUR once again.
30
Q

Meteorite and comet impacts:

A

Large meteorites (300km) impacted surface of Earth.

*Molten lava came up from Earth’s core and destroyed large ecosystems

  • volcanic eruptions
31
Q

Organism divergence from common ancestor:

A

All organisms came from a common ancestor that changed over time due to:
1. Changes in enviro
2. Mutations

32
Q

Define Mutations:

A

Sudden changes that occur in the genetic make-up (DNA) of organisms

33
Q

Explain Diversification:

A

Species diverged from each other as number of mutations increased

34
Q

Process of speciation:

A

Not able to INTERBREED and became separate species from each other.
(Number of Species increased)

35
Q

2 trends in changes evident over evolutionary time:

A
  1. Aquatic organisms came before terrestrial organisms in time
  2. Simple organisms came before complex organisms in time
36
Q

Define : Geological time scale:

A

A record of the formation of rocks and the appearance of organisms over geological time

37
Q

THREE ERAS (geological time scale):

A
  1. Paleozoic era - (period: cambrian)
  2. Mesozoic era - (triassic)
  3. Coenozoic era - (tertiary)
38
Q

The meaning and use if time scales:

A

Used by: geologists, palaeontologists and scientists

  • Describe the timing and relationships of events that have occurred during Earth’s history.

(Geological time)

39
Q

Define fossils:

A

Fossils are the remains of organisms which died thousands of years ago and were preserved in specific rock layers. (Dried sap: amber / ice, tar)

(Palaeontologists)

40
Q

Geological rock dating function

A

Fossils are embedded in rock layers

  • age of rock layer = age of fossil
41
Q

Explain the CAMBRIAN EXPLOSION

A
  • Rapid DIVERSIFICATION of organism and increase of : varied species
  1. During Cambrian period: Earth’s conditions = favourable for life : number of species diversified quickly.
42
Q

Why is the Cambrian explosion important?

A

Gives insight into origins of major forms of all animal groups

43
Q

2 types of extinction:

A
  1. Biological extinction
  2. Mass extinction
44
Q

Define: Biological extinction

A

All individuals of a single species or a few species die off at roughly the same evolutionary time

45
Q

Define: Mass extinction

A
  1. Large number of species die out at same evolutionary time
  2. Over thousands of years
  3. 5 mass extinctions occurred over geological time (Earth history)
  4. Present Rate of extinction: higher than ever
    (6th mass extinction)
46
Q

5 mass extinctions in past

2 MOST IMP:

A
  • 250 mya: (extinction of 90% of life)
  • 65 mya: (extinction of many species & Dinosaurs)

Dinosaurs were largest mammal in Earth
- their extinction allowed animals to diverge : ECOLOGICAL NICHES

Ecological niches:

An ecological niche is a species’ role in its environment. Diversification happens as species adapt to different niches, reducing competition and leading to the evolution of new species.

47
Q

Sequence of Vertebrae classes
(Least evolved —> most evolved)

A
  1. Fish
  2. Amphibia
  3. Reptilia
  4. Aves
  5. Mammalia
48
Q

How are fossils formed?

A

Fossils are only found in: Sedimentary rock
* The closer the organism to an aquatic environment, the more likely to fossilise over time
(Decomposes soft parts: mud)

49
Q

Process of fossilisation:

A
  1. Organism dies
  2. Covered by sediment (sand and water = sediment)
  3. Soft parts of body decomposed by microorganisms (bacteria)
  4. PERMINERALISATION: minerals of sediment move into hard parts of body (bones/shell)
  5. Soil gradually added in layers
  6. Weight of soil: compacts bottom layers (compression)
  7. Sedimentary rock layer formed : permineralized parts of organism in it
  8. Over time: fossil formed in sedimentary layer
  9. Older fossils : older rock layers
50
Q

Define: transitional fossils

A

Fossil that show characteristics of two different groups of organisms which follow in sequence over evolutionary time.
One group is more primitive (preceding) & other more advanced

(2 groups in succession)

51
Q

The fossil record:

A

All fossils that have been found in world are part of fossil record.

52
Q

The fossil record:

A

All fossils that have been found in world are part of fossil record.

53
Q

Fossil record: DISADVANTAGES (evolution)

A

incomplete

  1. Mainly hard-bodied organisms are represented in fossil record
    (Not all soft bodied organisms in resin were found)
  2. Gaps in record: affecting interpretation of origin of species over time
    (Mining & excavation)
  3. If hard- bodies organisms died far from water source: did not fossilise
  4. Did not fossilise in one place
    (Animals carried bones: skeletons scattered)
54
Q

Fossil record: DISADVANTAGES (evolution)

A

incomplete

  1. Mainly hard-bodied organisms are represented in fossil record
    (Not all soft bodied organisms in resin were found)
  2. Gaps in record: affecting interpretation of origin of species over time
    (Mining & excavation)
  3. If hard- bodies organisms died far from water source: did not fossilise
  4. Did not fossilise in one place
    (Animals carried bones: skeletons scattered)
55
Q

Fossil record: ADVANTAGES (evolution)

A
  1. Anatomy of fossils help classify and determine age
    (Simple organisms before complex organisms)
    ( descent by modification / natural selection: CHARLS DARWIN
  2. As new fossils are found: compared to existing fossils
  3. Transition fossils
    (Supports Darwinism: species transitioned from one group to next)
56
Q

Understanding fossils:

A

Scientists use DEDUCTIVE REASONING (interference) to understand fossils and history of life on Earth

57
Q

Understanding fossils:

A

Scientists use DEDUCTIVE REASONING (interference) to understand fossils and history of life on Earth

58
Q

Function of fossil dating and types:

A

Determine age of fossils

  1. Relative dating
  2. Absolute dating
59
Q

Relative dating:

A
  • Used before modern technology
  • index fossils used to determine age of other fossils : comparing relative to age of index fossils

INACCURATE

60
Q

Why are index fossils used?

A
  1. Widely distributed
  2. Many occur
  3. Age is well documented and existed in short space of time
61
Q

Absolute dating

A

(Radiometric dating)
RELIABLE & ACCURATE
*dates rock layer: fossil found in specific rock layer

Transitions into daughter element through radioactive energy loss

62
Q

Parent element/ isotope

A

Radioactive
- Unstable
- Decays / loses radioactivity at a fixed rate over time known to scientists.

63
Q

Parent element/ isotope

A

Radioactive
- Unstable
- Decays / loses radioactivity at a fixed rate over time known to scientists.
(Measured in half lives)

64
Q

Parent element/ isotope

A

Radioactive
- Unstable
- Decays / loses radioactivity at a fixed rate over time known to scientists.
(Measured in half lives)

65
Q

Daughter element

A

Stable element formed by radioactivity loss of parent isotope

66
Q

Define: one half life

A

The amount of time it takes for the radioactive isotope to lose half of its radioactivity

67
Q

What is fossil tourism?

A

A source of income, national and local pride and employment in some areas

68
Q

Fossil tourism: ECOLOGY

A

Advantage: promotes awareness and conservation of fossils & ancient ecosystems

Disadvantage: habitat disruption and degradation of natural sites

69
Q

Fossil tourism: FINANCES

A

Advantage: generate income for local communities and supports economy

Disadvantage: over reliance on tourism harms local economy if sites are exhausted

Life Sciences (4 decks)

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