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Year 11 > Earth and Environment - Prelim Study > Flashcards

Earth and Environment - Prelim Study Flashcards

1
Q

What are the compositional layers of the Earth’s layers in order from inside out?

A
  1. Inner core
  2. Outer core
  3. Mantle
  4. Asthenosphere
  5. Crust (lithosphere)
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2
Q

How did the Earth first form?

A

Molten Earth formed from the process of accretion from a nebula

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3
Q

When did Molten Earth form?

A

4.6 BYA

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4
Q

What is accretion?

A

Accretion is the accumulation of particles into a massive object by gravitationally attracting more matter

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5
Q

When did Molten Earth start cooling?

A

4 BYA (3.8 BYA Earth cools below 100 degrees Celsius and liquid water begins to form from the atmosphere)

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6
Q

What evidence do you use to determine the Earth’s age?

A
  1. Zircon Crystals - these grow in magmas and are nearly indestructible. The oldest Zircons found are up to 4.4 billion years old.
  2. Meteorite evidence - these are remnants from the original solar system. If we find one with Zircons it can give us an insight into the Earth’s starting point.
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7
Q

What is relative dating?

A

Relative dating is a type of dating, whereby the rock is compared to other rock layers. I.e. rock layer 2 is older than layer 3 but younger than layer 1

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8
Q

What is absolute dating?

A

Absolute dating determines the age of specimens, achieved through radiometric dating.
- The rock must be igneous. It determines the exact age of the rock/fossil in years.
- Half life of an isotope is how long it takes for half of the parent isotope to decay into the daughter isotopes to determine age
Example:
- Potassium - 40 → Agrogon - 40
- Carbon - 14 → nitrogen - 14

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9
Q

What are Mafic rocks?

A

Mafic rocks are dark coloured because they contain minerals richer in magnesium and iron like olivine, pyroxene and biotite

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10
Q

What are Felsic rocks?

A

Felsic rocks are light coloured because they contain more silica, feldspar and quartz, and are produced from magmas with higher water content, lower densities.

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11
Q

What are rock-forming solids called?

A

Minerals

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12
Q

What tests can be done to identify a mineral? (List 5)

A
  1. Hardness → resistance to being scratched (uses ‘Mohs Scale of Hardness’)
  2. Streak → powdered or crushed colour
  3. Lustre → Shininess of the surface of the mineral (ie. can be metallic or non-metallic, pearly, dull, earthy)
  4. Specific Gravity → density in relation to water
  5. Cleavage → number of natural breaks or splits
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13
Q

What is a mineral?

A

Minerals are natural substances in which the particles are arranged in patterns.

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14
Q

What 8 elements make up 99% of all minerals?

A
  1. oxygen
  2. silicon
  3. aluminium
  4. iron
  5. calcium
  6. sodium
  7. potassium
  8. magnesium
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15
Q

What are 3 examples of minerals?

A

Quartz
Mica
Feldspar
Hornblende
Calcite

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16
Q

How are rocks classified?

A
  1. Igneous
  2. Metamorphic
  3. Sedimentary
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17
Q

What are igneous rocks?

A

Igneous rocks are formed as magma cools and solidifies and are hard, brittle, homogenous (look the same in all directions)

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18
Q

What are the two types of igneous rocks?

A
  1. Igneous rocks (extrusive) - formed from lava. eg. basalt and pumice
  2. Plutonic igneous rocks (intrusive) - formed from magma deep underground. eg. granite
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19
Q

What are sedimentary rocks?

A
  1. Sedimentary rocks form when the supply of sediment is greater than its removal e.g. rivers.
  2. They are laid down in layers called strata.
    Lower layers are older than the upper levels (called the Law of Superposition)
  3. Sometimes rich in fossils, which can indicate the environmental conditions at the time of deposition
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20
Q

How are sedimentary rocks classified?

A
  1. Grain size – the individual grains or fragments can be measured and the sorting of the grains can be used (eg. sand to sandstone; mud to shale)
  2. Grain shape – the roundness or angularity of the grains (eg. if the agent of erosion is water the grains will be more rounded)
  3. Composition
    - Clastic rocks – made up of fragments of other rocks (clasts). E.g. quartz, feldspar
    - Non-clastic rocks – consist of carbonate (limestone), silica or carbon (coal) and are formed from once living organisms or chemical precipitation of minerals
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21
Q

What are metamorphic rocks?

A

Metamorphic rocks are formed from existing rocks (country rocks) that have been altered by heat and/or pressure.

They are hard, brittle and can have bands of different minerals which are orientated, bands often folded.

They can recrystallise as an entirely different mineral producing a rock with totally different properties.

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22
Q

What is thermal or contact metamorphism?

A

This is when rocks are changed predominantly by heat and occurs in relatively small areas.

It occurs when magma pushes into surrounding rocks.

E.g. marbles

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23
Q

What is regional metamorphism?

A

This is when heat and pressure act together.

As you go deeper into the Earth the temperature increases.

Mountain building due to plate tectonics causes the folding of rocks which also generates heat.

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24
Q

What are some common metamorphic changes? (List 3)

A
  1. Limestone changes to marble
  2. Granite changes to genesis
  3. Shale changes to slate
  4. Phyllite changes to schist
  5. Sandstone changes to quartzite
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25
Q

List 3 igneous rocks?

A
  • Andesite
  • Basalt
  • Granite
  • Obsidian
  • Pumice
  • Diorite
  • Tuff
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26
Q

List 3 sedimentary rocks?

A
  • Sandstone
  • Siltstone
  • Coal
  • Limestone
  • Shale
  • Conglomerate
  • Dolomite
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27
Q

List 3 metamorphic rocks?

A
  • Gneiss
  • Hornfels
  • Slate
  • Schist
  • Quartzite
  • Marble
  • Phyllite
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28
Q

What is soil made up of? (List 4)

A
  1. Minerals - the process of weathering reduces the parent rock to the constituent minerals. It can occur locally or brought in by wind, water and gravity.
  2. Organic matter – litter is undecomposed and is found on the surface of the soil; Humus is a flakey black matter consisting of decomposed animals and plants. It increases the water holding capacity of the soil.
  3. Water – due to the shape of the grains, there are many spaces in the soil (called pores) which are fill up with water when it rains.
  4. Air – soil air comes from the atmosphere and the gases that are formed from biological and chemical reactions within the soil. The air is found in the pore spaces between the grains.
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29
Q

What are the 4 ‘horizons’ which form the soil structure?

A

A Horizon → Usually darkest, contains the most organic matter
B Horizon → Brightest colour, more soluble minerals here by leaching
C Horizon → Broken pieces of bedrock with clay
D Horizon (bedrock) → Not considered soil

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30
Q

What are the 2 main factors that affect the amount of soil water?

A
  1. Porosity → the volume of pore spaces in the soil
  2. Permeability → how freely water moves through the soil
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31
Q

What is Indigenous mining?

A

Indigenous Australians depended on their stone implements to gather and process their food; ochre was a vital ingredient in art and religious practices; quarries and ‘processing’ sites were developed to cater for the demand for these products; and transport routes were established to allow for their trade.

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32
Q

How many Indigenous mining sites are recorded in eastern Australia?

A

416

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33
Q

What is the theory of Continental Drift and who first developed the theory?

A

Relative movement of the continents over the ocean bed
Speed varies from 3 - 8 cm a year
Alfred Wegner

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34
Q

Was Continental Drift proved or disproved? When? By whom?

A

Disproved

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35
Q

What theory replaced the theory of Continental Drift?

A

Plate Tectonics Theory

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36
Q

What is the theory of Plate Tectonics?

A

The crust of the Earth is divided into numerous rigid slabs of crust called plates, each of which is moving relative to each other

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37
Q

When was the theory of Continental Drift first developed?

A

1930’s

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38
Q

When was the theory of Plate Tectonics first established?

A

1960’s

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39
Q

What is the ‘jigsaw fit’ of the continental shelves and corresponding scientist?

A

Continents fit together
Alfred Wegner

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40
Q

What was the Supercontinent called?

A

Pangaea

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41
Q

When did the Supercontinent break up and draft away from one another and what were the two new continents called?

A

About 200 million years ago
Laurasia
Gondwana

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42
Q

When did Gondwana break up and what did it form?

A

About 140 million years ago
Australia, South America, Antartica, India, Africa and parts of South East Asia

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43
Q

Jigsaw fit is one piece of evidence for the theory of tectonic plates. What are the other 5 and what scientist contributed to the evidence?

A
  1. Matching fossils and rocks - deposits and fossils match up over wide areas, ie. when continents are placed together.
    Alfred Wegner
  2. Convection current – heat from the mantle causes upwelling at mid-ocean ridge (MOR). Ridge push and slab pull aid in moving the plates.
    Arthur Holmes
  3. Sea-floor spreading - at mid-ocean ridges new crust is created
    Harry Hess
  4. Ocean floor - dating of the ocean floor supports Hess’ sea-floor spreading
    Glomar Challenger
  5. Magnetic reversals - shows the matching magnetic orientation of the rock on either side of the mid-ocean ridge
    Frederick Vine and Drummond Matthews
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44
Q

What is ‘density’?

A

Density of an object refers to how heavy it is given how much space it takes up

This depends of how closely packed the molecules are

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45
Q

How do you calculate density?

A

Density = Mass (g) \ Volume (cm3)

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46
Q

What is the theory of Plate Tectonics?

A

Is is the theory in which the lithosphere (earth’s crust) is divided into a number of plates, each of which moves on the plastic asthenosphere to collide with, slide under, or move post adjacent plates.

The oceanic and continental plates move, float and sometimes fracture, this interaction causes continental drift, earthquakes, volcanoes, mountains and oceanic trenches.

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47
Q

How many tectonic plates is the Earth’s crust divided into?

A

About 15

48
Q

What are the 8 main tectonic plates?

A

African
Antarctic
Eurasian
Indo-Australian
North America
Pacific
South America
Nazca

49
Q

What are the tectonic plate boundary types?

A
  1. Transform boundaries
  2. Divergent boundaries
  3. Convergent boundaries
50
Q

What are the two characteristics of tectonic plates?

A
  1. Oceanic - is relatively thin (5 - 10 km thick, may be up to 70 km)
    Rock type - Mafic, e.g. basalt, often formed from mid-ocean ridges. Rich in magnesium and aluminium. Soft sediments
  2. Continental - is relatively thick (25 - 50 km thick, may be up to 150 km)
    Rock type - Felsic, e.g. granite formed from slow cooling. Rich in silica and aluminium. Hard sediments.
51
Q

What are reverse faults and folds?

A

When plates collide, compressional forces and cause rocks to bend or fold which produces anticlines and synclines

If the forces are very large or occur over a short time or the rocks are brittle, they may snap to produce reverse faults

52
Q

Where is Magma formed?

A

Magma is mostly formed at subduction zones, and mid-ocean ridges

It is sometimes formed in hotspots or by intra-plate melting

53
Q

What affects Magma formation?

A

Temperature, pressure, water content and mineral composition affects magmas formation

54
Q

What does increasing pressure do to magma?

A

Raises the melting point

55
Q

What does increasing water content do to magma?

A

Lowers the melting point

56
Q

Where does Mafic magma form?

A

Forms within the upper mantle

57
Q

What is the heat energy from magic magma?

A

It is hotter and contains more high density materials such as iron and magnesium

When released it creates a thermal plume and then an effusive eruption.

58
Q

What temperature does Felsic magma form - higher or lower?

A

Lower

59
Q

Where does Felsic magma form?

A

Formation occurs near the base of the lithosphere when a subducted plate is partially melted.

Because if its relatively high viscosity, felsic magma is resistant to flow and plugs volcanic vents, causing a build-up of pressure releasing violently. This resistance to flow also produces steep sided, symmetric volcanoes.
E.g. Andes mountains of South America

60
Q

What types of eruptions are there? (List 2)

A

effusive (shield volcanoes) or
explosive (composite volcanoes)

61
Q

What type of volcano does mafic magna form?

A

effusive eruption

62
Q

What is an effusive eruption (or shield volcano)?

A

An eruption where:
-mmafic magma formed in upper mantle.
- depth of formation leads to hotter magma, with more dense material.
- magma rises into thermal plume below surface.
- released as a flowing magma, with lower viscosity allowing gas to escape more easily.

63
Q

What type of volcano does Felsic magma form?

A

Explosiv eruption

64
Q

What is an explosive eruption (or composite volcano)?

A
  • Felsic magma form partially melted subjected oceanic plates
  • Buildup of pressure from plugged vents
  • Viscous magma, slow flowing forming steep sided composite volcanoes
65
Q

What is the ‘hydrosphere’?

A
  • The hydrosphere is the liquid water component of the Earth.
  • It includes the oceans, seas, lakes, ponds, rivers and streams.
  • The hydrosphere covers about 70% of the surface of the Earth and is the home for many plants and animals.
66
Q

What is the water cycle?

A
  • The water cycle is the natural movement of water in the environment.
  • The Sun evaporates water from lakes, rivers, the land and the sea. In the atmosphere the water condenses to form clouds. The water falls back to earth as rain, snow, sleet, dew or fog.
  • The energy to operate the water cycle comes from the Sun.
67
Q

What is the global water budget?

A
  • Total distribution of water in all its forms and in all its natural reservoirs on Earth.
  • Can be classified as ocean (salt) or fresh water (includes ice and water vapour).
  • Earth has an uneven distribution of liquid water, even though it has more than anywhere else in the Solar System.
68
Q

What is the role of water on Earth?

A
  • Water has many properties that make it a unique substance and helps drive many systems of earth both living (biotic) and non-living (abiotic)
  • Water is necessary for all living matter
  • It is used for:
    A solvent to allow life processes to occur (reactions in cells)
    Used as a raw material in chemical reactions
    It transports materials to and from cells
    It helps with temperature regulation
69
Q

What affects the boiling point of water?

A

Boiling point is affected by pressure and dissolved chemicals
E.g adding salt will raise the boiling point

At sea level it is 100℃, at the top of Kosciuszko it is 97.5℃

70
Q

What affects the density of water?

A

Temperature
- Colder water is more dense because the particles are closer together. This causes it to sink

  • Particles in warmer water will have more, creating more space and are therefore less dense
71
Q

What is surface tension of liquid?

A

The force acting on the surface of a liquid, keeping the area of the surface as small as possible.

The force acts at right angles to the surface and causes liquids to form a ‘film’ on the surface or to form droplets

The force is due to the attraction between the particles of liquid

72
Q

Why is water often known as the ‘universal solvent’?

A

It dissolves most substances

73
Q

What is a solute?

A

The substance that is to be dissolved

74
Q

What are El Niño and La Niña events and when do they occur?

A

A natural part of the global climate system.

They occur when the Pacific Ocean and the atmosphere above it change from their neutral (‘normal’) state for several seasons and occur every 3 - 7 year

75
Q

What weather does El Niño bring to Australia?

A

Drier weather

76
Q

What weather does La Niña bring to Australia?

A

More rain

77
Q

What factors help create El Niño and La Niña?

A
  • wind/air currents
  • Ocean currents and upwellings
  • Evaporation and cloud formation
  • The water cycle
78
Q

What is the cryosphere?

A

The cryosphere → is the frozen water part of the Earth’s system

79
Q

What are the major components of the cryosphere?

A

The Arctic, Antarctica and Greenland

Other components are snow, ice, glaciers and permafrost located around the globe

80
Q

What is the ‘positive feedback loop’ in relation to the cryosphere?

A

Snow and ice reflects heat from the sun, helping to regulate our planet’s temperature

As the planet heats up the cryosphere shrinks, causing further heating

As ice melts the albedo (reflection) reduces, causing more sunlight to be absorbed

This causes more ice to melt further reducing the albedo, further heating up

81
Q

What affects water quality? (List at least 4)

A
  1. Oxygen-demanding substances
  2. Pathogens
  3. Synthetic organic compounds
  4. Nutrients
  5. Inorganic chemicals
  6. Sediments
  7. Radioactive substances
  8. Thermal discharge
82
Q

What are transform boundaries?

A

where plates slide past each other

E.g.San Andreas fault (pacific and North American plates sliding past each other)

83
Q

What are divergent boundaries?

A

spreading ridges - as plates move apart magma fills up the gap

Example (continental): iceland is continental rifting (rift valley)
Iceland has a divergent plate boundary running through its middle

Example (Oceanic): Mid-Atlantic Ridge is a mid-ocean ridge (MOR) formed from plates diverging

84
Q

What are convergent boundaries? (3 types)

A

There are three types of convergent boundaries:
- Continent - continent convergence
Folded mountain range with large Earthquakes and NO volcanoes E.g: Himalayas mountain range (Indian and Eurasian plates colliding)

  • Continent - oceanic convergence, where
  • Oceanic plates subducts underneath the continental plate
  • Oceanic plate heats and melts
  • The melt rises forming volcanic mountain range
  • Example: The Andes volcanic mountain range (Nazca and South American Plates)
  • Ocean - ocean convergence
    The subduction plate is bent downwards to form a very deep depression in the ocean floor called a trench
    Forms a volcanic Island arc
    E.g. Japan and the Mariana Trench (pacific and Mariana plates)
85
Q

What are oxygen-demanding substances?

A

Usually organic material that is not entirely decomposed, for example, untreated or partially treated sewage.

As the organic material enters a body of water, it continues to decompose and uses up oxygen from the water during the process.

This reduces the level of dissolved oxygen available for aquatic plants and animals and also acts as a nutrient.

86
Q

What are pathogens?

A

Organisms that cause disease if present in concentrated amounts in an ecosystem.

For example, protozoan parasites Giardia and Cryptosporidium contaminated Sydney’s water supply in 1998.

These can cause intestinal cramping and explosive diarrhoea.

Other waterborne diseases common to Third World countries can be fatal, such as cholera and typhoid.

87
Q

What are synthetic organic compounds?

A

These are human manufactured chemicals predominantly made up of carbon and hydrogen. The most common types that pollute water are petrol and oil.

Oil spills float on water, preventing light penetration for photosynthesis and covering shoreline food supplies. They typically blind, poison or drown fish, birds and mammal species.

88
Q

What nutrients can affect water quality?

A

These are natural or synthetic substances that promote plant growth. These typically contain nitrogen and/or phosphorus and include manure, humus, detergents, and fertilisers.

The artificial promotion of plant growth in waterways favours weed species over natives. It can also promote algal blooms.

89
Q

What are inorganic chemicals?

A

These are either pesticides and herbicides using in farming or substances released by industrial processes.

These substances interfere with the normal functioning of individual organisms or entire ecosystems.

Heavy metals released by some industries can accumulate in the food chain, causing skeletal malformation and a variety of diseases.

90
Q

What are sediments in water?

A

Undisturbed water environments are usually clear. Sediments can increase due to flooding and land clearing.

Turbidity – how murky water is.

Light cannot penetrate far down through water with a high turbidity, which can impact on bottom-dwelling aquatic plants.

Stratification – formation of thermal layers in dams due to turbidity. This occurs when highly turbid waters in dams become heated by the sun and results in less gas exchange because of the warm temperature on the surface.

91
Q

How do radioactive substances affect water?

A

Radiation damages DNA in the cells of living things, resulting in diseases and mutations.

In 2011 the Fukushima nuclear meltdown after an earthquake and tsunami contaminated large areas.

Australia’s only nuclear reactor is at Lucas Heights, Sydney. Small reactor that produces radioactive isotopes for research, industry and hospitals. Concerns about the effect of buried low to medium level radioactive materials in the local environment.

Tailings dam– sediments left over from mining. Main reason for failure of the NT uranium mine.

92
Q

What is thermal discharge?

A

Hot water holds a lot less dissolved gas than cold water. Some industries that use water as a coolant, such as power stations, release their waste water into dams or streams.

Although it may be free of chemical pollutants, this warm water can cause the suffocation or redistribution of plant and animal life in response to decreased oxygen and carbon dioxide levels.

93
Q

What are the main sources of water pollutants? (List 4)

A
  1. Sewage - most of Australia’s sewage, from septic tanks to tertiary treated effluent, eventually ends up in oceans, rivers or ground water. To reduce this, some water authorities have set up programs to reuse treated effluent as a soil conditioner for agricultural use. Another method being trialled is large scale worm farming, which turns treated effluent into a disease free organic fertiliser.
  2. Industrial waste - industry can be a major producer of water pollutants, especially of synthetic organic compounds and inorganic chemicals.
  3. Garbage and refuse - stormwater run-off flushes huge amounts of litter and vegetation into streams and onto beaches.
    While collected rubbish is generally quickly buried at landfill sites, water movement through the soil at these sites can contaminate nearby waterways with a wide variety of chemical pollutants if barriers to prevent
  4. Agriculture - the vast majority of Australian farmland is relatively infertile and farmed at near maximum capacity.
    This requires the addition of fertilisers to replenish soil nutrients and the use of herbicides and pesticides to eliminate competition to crops. Usually administered as water soluble liquids, they are inevitably washed into waterways and groundwater supplies.
94
Q

What is Eutrophication?

A

Process where nutrients become concentrated in waterways, causing an explosion in the population of microscopic algae and cyanobacteria. The water becomes discoloured in an algal bloom.

Algal blooms prevent light from penetrating the water which stops the bottom dwelling plants from carrying out photosynthesis. They also use up the oxygen which kills living organisms.

95
Q

What increases the process of eutrophication?

A

Human activity

96
Q

How does eutrophication clear?

A

Usually clears with rainfall which will replenish with clean water.

97
Q

What is cyanobacteria?

A

It is a blue-green algae which is common in Australia and is formed from fertilisers in low flow inland rivers. Produces toxins that can kill humans and cattle that drink it or produce rashes on those who bathe in it.

It is a type of eutrophication.

98
Q

What is ‘salinity’?

A

The presence of soluble salts of sodium, magnesium and calcium in the soil and water.

99
Q

Why and where does natural salinity occur in Australia?

A

There has been weathering of marine sediments from ancient inland seas and ancient sand dunes such as in northern SA, (e.g. Lake Eyre) southern NT and southern WA.

Salts have been blown as sea spray from the oceans and deposited by rain as in parts of WA.

Some saline areas are, quite naturally, completely unsuitable for agriculture or grazing. However, many areas are in use because the natural salinity was mostly deep in the sub-soil and did not interfere with plant growth. Unfortunately, some human land-use practices have caused salinity to come to the surface.

100
Q

What is drylands salinity?

A

Clearing - where the deep-rooted native trees and shrubs have been largely replaced by shallow-rooted grasses grown as pasture.

This has become a problem mainly in semi-arid land cleared for grazing - eg. particularly in south-west WA.

101
Q

What is irrigation salinity?

A

Due to over-irrigation of crops, combined with the clearing of native vegetation.

Major problem in a number of areas, including the Murray-Darling catchment area which covers large areas of central and western NSW.

102
Q

What cases soil salinity?

A

Land clearing
Irrigation

103
Q

How has human land use caused soil salinity?

A

In many parts of semi-arid Australia the deep sub-soil contains saline groundwater.
Its “water table” is kept low because transpiration from the deep-rooted native vegetation constantly removes moisture from the soil.
There is a balance between incoming water as rainfall, and outgoing evaporation and transpiration.

When land is cleared for grazing or for irrigated farming, from 10 times to 100 times more water percolates downwards into the sub-soil.
This raises the water table, bringing salt with it. Salt reaching the plant root zone kills plants, both native and crops.

104
Q

What are the impacts of soil salinity? (List 5)

A
  1. Loss of productivity of agricultural and grazing land.
  2. Increased soil erosion due to reduced vegetation cover.
  3. Increased salinity of streams creates problems for human water supplies and irrigation schemes.
  4. Salt damage to roadways, concrete structures, water pipes and buildings, due to corrosion and salt crystallisation.
  5. Ecosystems are threatened. Soil salinity can kill native vegetation, and this deprives animals of food and habitat. Salinity in waterways affects the aquatic ecosystems by causing osmosis problems in all organisms.
105
Q

What are the strategies/mitigation methods for rehabilitation of salinity-affected areas?

A

Rehabilitation often involves maintaining the water table below the soil and includes:

  1. Reducing the amount of rainwater reaching the water table by planting trees and shrubs to absorb and evaporate the rainwater.
  2. Modern farming techniques allowing farmers to closely monitor soil moisture levels in irrigation areas to avoid overirrigation. Some crops can use drip irrigation rather than spray irrigating the entire paddock.
  3. Government investing in salt interception schemes – borehole drilled into salty aquifers. Water that comes to the surface is fed into large basins where it is evaporated. Prevents salty water reaching streams.
  4. Intermittently plant deep rooted trees on edges of crops or salt tolerant plants
  5. Rotate crops with deeper roots
106
Q

What is soil erosion?

A

Removal of surface layers or topsoil from an area.

The topsoil is nutrient rich and vital to plant growth. It can take decades to develop.

107
Q

How is soil eroded?

A

Blown away by wind or washed away by water.

Wind - sandy and fine-grained soils are easily picked up and carried along by the wind. If there is no major vegetation, the wind can pick up speed and carry more soil.

Water - moving water can remove larger particles than wind. Soil that has been laid bare by overstocking, or by rabbit plague, can be eroded away when a major rain event occurs. Gully erosion then occurs and reduces the area available for growing crops or livestock.

108
Q

What are the effects of invasive species on the ecosystem?

A
  1. Direct competition with native species
  2. Loss of species diversity – may cause native species to become endangered
  3. Short-circuit interactions in natural communities & disrupt natural food web
  4. Direct Predation
  5. Affect entire ecosystem functions as water availability and nutrient cycle
109
Q

What are the economic effects of invasive species?

A
  1. Billions of dollars in damage to forests, property values, agricultural productivity, public utility operations, native fisheries, tourism, outdoor recreation
  2. Billions of dollars in programs by federal and state agencies to control invasive species
  3. $137 billion in damages per year
110
Q

What are the effects of invasive species on native species? (List 2)

A
  1. Feral animals such as rabbits, goats, pigs, and camels compete with native grazing animals.
  2. Feral rabbits can take over the burrows of native bilbies and bandicoots.
  3. Feral cats and foxes hunt and kill many native species and have wiped out numbats and mallee fowl from some regions.
  4. Introduced fish such as mosquito fish and European carp feed on native fish, competing with native fish for food or habitat, uprooting aquatic vegetation, disturbing sediments and introducing diseases or parasites.
111
Q

How do you control invasive species?

A
  1. Prevention
    Preventing invasive species from being introduced somewhere in the first place, or preventing them from spreading if they do arrive, is the key to avoiding long-term harm to ecosystems
  2. Eradicating potential invaders soon after invasion
    The complete and permanent removal of a pest. No pest animal has ever been eradicated from mainland Australia
  3. Physical (manual and mechanical)
    Controlling plants:
    Mechanical – excavation, trimming, etc.
    Removal of plants by hand
    Installation of growth barriers
    Controlling animals:
    Culling
    Trapping and hunting
    Putting up barriers or fences
  4. Cultural - ecosystem management
  5. Biological - natural enemies
    Biological control is using living organisms to control the pest. Agents must be carefully assessed before release to ensure the control species will not become invasive itself e.g. cane toad.
  6. Chemical - pesticides
    Chemical control involves applying poison to eliminate invasive species
    Insecticides & pesticides to control insect pests
    Herbicides (weed-killer) to control plants
  7. Integrated pest management - uses a combination of the above methods - most effective
112
Q

What are the effects of invasive species control method?

A
  1. Biological – control species can become invasive
  2. Chemical – may kill native species
  3. Physical – may miss removing some of the invasive species
  4. Prevention – apathy and lack of awareness
113
Q

What is an independent variable?

A

This is the things that you change in your experiment and are interested in how this change affects results. In a valid experiment there is only one independent variable.

For example, in my experiment, the thing I am changing is how much light each plant is exposed to.

114
Q

What is a dependent variable?

A

This is the thing that you are measuring

For example, in my plant experiment, I am measuring how tall my plants grow in centimetres.

115
Q

What is the control variable?

A

This is everything else that must be kept the same in order to maintain a fair test. This is important so that we can conclude that the effect we are observing is because of our independent variable and not some other factor.

For example, in my plant experiment I should water all the plants the same, use the same soil to plant them in, use the same plant seed etc.That way I can say that any changes in plant growth can only be due to their different sunlight exposure as all else in the experiment was kept the same.

116
Q

What are the 6 steps of the scientific method?

A

Observation
Question
Hypothesis
Experiment
Results
Conclusion

Year 11 (4 decks)

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