HSC Earth and Environmental Science cheat sheet

Earth has four interacting spheres: geosphere (rock), atmosphere (gas), hydrosphere (water), and biosphere (living things); a change in one sphere propagates through the others.

Earth's internal heat drives plate tectonics, volcanism, and mountain building; solar energy drives weather, climate, ocean currents, and the water cycle.

The rock cycle links igneous, sedimentary, and metamorphic rocks; melting, weathering, erosion, deposition, and metamorphism are the transforming processes.

The water cycle: evaporation, transpiration, condensation, precipitation, infiltration, runoff, and groundwater flow; energy is absorbed at evaporation and released at condensation.

The carbon cycle exchanges carbon among the atmosphere, oceans, biosphere, soils, and rocks; combustion and respiration release CO2, photosynthesis and ocean uptake remove it.

The nitrogen cycle depends on fixation (lightning, bacteria), nitrification, assimilation, and denitrification; nitrogen is often the limiting nutrient in ecosystems.

Feedbacks are positive (amplifying) or negative (stabilising); ice-albedo feedback is positive, while increased evaporation producing more cloud cover can be negative.

The geological timescale orders Earth history: Precambrian, Palaeozoic, Mesozoic, Cenozoic; relative dating uses superposition and cross-cutting, absolute dating uses radiometric decay.

Earth's layers: crust (thin, silicate), mantle (peridotite, convective), outer core (liquid iron-nickel), inner core (solid iron-nickel); the Moho marks the crust-mantle boundary.

Plate boundaries: divergent (new crust, mid-ocean ridges), convergent (subduction or collision, trenches and fold mountains), transform (lateral sliding, earthquakes).

Seafloor spreading creates symmetrical magnetic stripes and progressively older crust away from ridges, evidence for continental drift and plate tectonics.

Igneous rocks crystallise from magma; intrusive types are coarse-grained (granite, gabbro), extrusive types are fine-grained (basalt, rhyolite).

Sedimentary rocks form by compaction and cementation of sediments; they preserve fossils and give evidence of past environments and relative age.

Metamorphic rocks form under heat and pressure; foliated types (schist, gneiss) align minerals, non-foliated types (marble, quartzite) do not.

Mineral resources are non-renewable; ore grade, accessibility, and economic concentration determine viability, and extraction produces tailings and acid mine drainage.

Fossil fuels form from buried organic matter under heat and pressure over millions of years; coal from terrestrial plants, oil and gas from marine plankton.

The atmosphere is 78% nitrogen, 21% oxygen, about 0.93% argon, and 0.04% carbon dioxide, plus variable water vapour; ozone concentrates in the stratosphere.

The greenhouse effect: gases absorb outgoing longwave radiation and re-emit it, warming the surface; key gases are water vapour, CO2, methane, nitrous oxide, and CFCs.

Temperature falls with altitude in the troposphere (lapse rate about 6.5 degrees C per km) and rises in the stratosphere because ozone absorbs ultraviolet radiation.

Coriolis effect deflects moving air and water: to the right in the Northern Hemisphere and to the left in the Southern Hemisphere; it is zero at the equator.

Global circulation cells (Hadley, Ferrel, Polar) and pressure belts create prevailing winds and determine wet equatorial and dry subtropical climate zones.

Ocean currents are driven by wind and density differences (temperature and salinity); surface currents redistribute heat, and upwelling brings nutrient-rich deep water to the surface.

El Nino-Southern Oscillation alters Pacific pressure and currents, shifting rainfall and causing drought in eastern Australia and floods in the eastern Pacific.

Relative humidity is the ratio of actual vapour content to saturation capacity; air cools to the dew point and condenses, forming cloud and precipitation.

Ecosystems have biotic components (producers, consumers, decomposers) and abiotic components (light, temperature, water, soil, nutrients) that interact.

Energy flows one way through trophic levels; only about 10% transfers to the next level, so food chains rarely exceed four or five levels.

Photosynthesis: 6CO2 + 6H2O + light gives C6H12O6 + 6O2; respiration reverses it, releasing energy for metabolism.

Nutrient cycles (carbon, nitrogen, phosphorus) recycle matter, unlike energy, which is not recycled.

Biodiversity includes genetic, species, and ecosystem diversity; it increases ecosystem resilience to disturbance.

Population size changes through births, deaths, immigration, and emigration; carrying capacity is the maximum population an environment can sustain.

Symbiosis includes mutualism (both benefit), commensalism (one benefits, other unaffected), and parasitism (one benefits, host harmed).

Adaptations are structural, behavioural, or physiological; Australian examples include sclerophyll leaves, fire-germinating seed, and nocturnal behaviour.

Eutrophication: nutrient runoff causes algal blooms, then decomposition depletes oxygen and creates dead zones.

Salinity and soil degradation result from rising water tables, irrigation, and land clearing; management includes revegetation, drainage, and reduced irrigation.

Air pollution indicators include particulate matter (PM10, PM2.5), sulfur dioxide, nitrogen oxides, ozone, and carbon monoxide; standards set maximum concentrations.

Climate change mitigation reduces greenhouse gas sources or enhances sinks; adaptation adjusts systems to expected impacts.

Environmental impact assessment identifies, predicts, and mitigates impacts before a project proceeds; it includes scoping, baseline data, and monitoring.

Sustainability requires balancing ecological, economic, and social needs; renewable resources must be used below their regeneration rate.

Introduced species and habitat fragmentation are major causes of biodiversity loss; conservation strategies include reserves, corridors, and captive breeding.

Waste management hierarchy, from most to least preferred: avoid, reduce, reuse, recycle, recover energy, dispose.

Dependent variable is measured, independent variable is manipulated, and controlled variables are held constant to ensure a fair test.

Validity concerns whether the method measures what it claims; reliability concerns whether repeated measurements give consistent results.

Accuracy is closeness to the true value; precision is closeness of repeated measurements to one another.

Random errors scatter results around the true value and are reduced by averaging; systematic errors shift all results in one direction and require calibration.

Percentage error = (measured value minus accepted value) divided by accepted value, multiplied by 100.

Fieldwork tools: quadrats estimate density and percentage cover; transects sample along a line; capture-recapture estimates population size as (M times C) divided by R.

Contour lines join points of equal elevation; closely spaced contours indicate steep slopes, and a river flows downhill perpendicular to contours.

A climograph plots monthly temperature as a line and monthly rainfall as bars, allowing climate classification and comparison of sites.

Earth's four spheres are the geosphere, atmosphere, hydrosphere, and biosphere; matter and energy move between them, so a change in one sphere alters the others.

Two energy sources drive Earth systems: internal heat from radioactive decay and primordial heat drives tectonics and volcanism; solar radiation drives climate, weather, and the water cycle.

The rock cycle transforms material among igneous, sedimentary, and metamorphic rock through melting, cooling, weathering, erosion, deposition, compaction, and metamorphism.

In the water cycle, evaporation and transpiration absorb latent heat while condensation releases it, which transfers energy from the surface into the atmosphere.

The carbon cycle exchanges carbon between the atmosphere, oceans, biosphere, soils, and rocks; photosynthesis and ocean uptake remove carbon dioxide and combustion and respiration release it.

The nitrogen cycle requires fixation by lightning and bacteria, then nitrification, assimilation, and denitrification; nitrogen is commonly the limiting nutrient in ecosystems.

Positive feedbacks amplify change (ice-albedo loss reduces reflection and increases warming); negative feedbacks stabilise systems (more evaporation producing more cloud cover).

Relative dating uses superposition, cross-cutting relationships, and fossil correlation; absolute dating uses radiometric decay of isotopes such as carbon-14 and potassium-40.

Earth's internal structure: thin silicate crust, convective peridotite mantle, liquid iron-nickel outer core, and solid iron-nickel inner core; the Moho is the crust-mantle boundary.

Divergent boundaries create new oceanic crust at mid-ocean ridges; convergent boundaries produce subduction zones with trenches, volcanic arcs, or collision fold mountains; transform boundaries produce lateral faulting.

Evidence for plate tectonics includes symmetrical magnetic stripes on the seafloor, increasing crustal age away from ridges, matching continental fossils and rock sequences, and earthquake and volcano distribution.

Igneous rocks crystallise from magma; slow cooling at depth gives coarse-grained intrusive rocks (granite, gabbro) and rapid cooling at the surface gives fine-grained extrusive rocks (basalt, rhyolite).

Sedimentary rocks form by compaction and cementation of weathered and eroded sediment, preserving fossils and cross-bedding that record past environments and relative age.

Metamorphic rocks form under heat and pressure; foliated types (schist, gneiss) align minerals in bands, while non-foliated types (marble, quartzite) do not.

Ore deposits are non-renewable and viable only when grade, depth, and location make extraction economic; mining produces tailings, acid mine drainage, and land disturbance.

Fossil fuels form from buried organic matter under heat and pressure over millions of years: coal from terrestrial plants, oil and gas from marine plankton and algae.

Dry air is about 78% nitrogen, 21% oxygen, 0.93% argon, and 0.04% carbon dioxide, with variable water vapour; ozone concentrates in the stratosphere.

The greenhouse effect occurs because gases such as water vapour, carbon dioxide, methane, nitrous oxide, and CFCs absorb outgoing longwave radiation and re-emit it, warming the surface.

Temperature decreases with altitude in the troposphere at about 6.5 degrees C per km and increases in the stratosphere because ozone absorbs ultraviolet radiation.

The Coriolis effect deflects moving air and water to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, and is zero at the equator.

Global circulation cells (Hadley, Ferrel, and Polar) and associated pressure belts create prevailing winds and explain wet equatorial and dry subtropical climate zones.

Ocean currents are driven by wind and by density differences from temperature and salinity; surface currents redistribute heat and coastal upwelling brings nutrient-rich deep water to the surface.

The El Nino-Southern Oscillation shifts Pacific pressure and current patterns, bringing drought to eastern Australia and heavy rain to the eastern Pacific during El Nino.

Relative humidity is the ratio of actual water vapour to the saturation capacity at that temperature; cooling air to its dew point causes condensation and cloud formation.

Ecosystems consist of interacting biotic components (producers, consumers, decomposers) and abiotic components (light, temperature, water, soil, nutrients).

Energy flows one way through trophic levels, with only about 10% transferred to the next level, so food chains rarely exceed four or five levels.

Photosynthesis is 6CO2 + 6H2O + light giving C6H12O6 + 6O2; respiration reverses this reaction to release energy for metabolism.

Carbon, nitrogen, and phosphorus cycle through ecosystems and are recycled, whereas energy is not recycled and must be continually supplied by the Sun.

Biodiversity includes genetic, species, and ecosystem diversity, and higher biodiversity generally increases ecosystem resilience to disturbance.

Population size changes through births, deaths, immigration, and emigration; carrying capacity is the maximum population an environment can sustain.

Symbiosis includes mutualism (both species benefit), commensalism (one benefits and the other is unaffected), and parasitism (one benefits and the host is harmed).

Adaptations are structural, behavioural, or physiological; Australian examples include sclerophyll leaves, seeds that germinate after fire, and nocturnal activity.

Eutrophication occurs when nutrient runoff triggers algal blooms; decomposition then depletes dissolved oxygen and creates hypoxic dead zones.

Dryland salinity results from rising water tables after land clearing and irrigation; management includes revegetation, drainage, and reduced irrigation.

Air quality is assessed using particulate matter (PM10, PM2.5), sulfur dioxide, nitrogen oxides, ozone, and carbon monoxide, compared against national standards.

Climate change mitigation reduces greenhouse gas sources or enhances sinks; adaptation adjusts human and natural systems to expected impacts.

Environmental impact assessment identifies, predicts, and mitigates impacts before approval; it involves scoping, baseline data, prediction, and monitoring.

Sustainability balances ecological, economic, and social needs; renewable resources must be harvested below their regeneration rate.

Introduced species and habitat fragmentation are major causes of biodiversity loss; conservation strategies include reserves, wildlife corridors, and captive breeding.

The waste hierarchy, from most to least preferred: avoid, reduce, reuse, recycle, recover energy, and dispose to landfill.

The independent variable is manipulated, the dependent variable is measured, and controlled variables are held constant to ensure a fair test.

Validity concerns whether a method measures what it claims to measure; reliability concerns whether repeated measurements give consistent results.

Accuracy is closeness to the true value; precision is closeness of repeated measurements to one another.

Random errors scatter results around the true value and are reduced by averaging; systematic errors shift all results in one direction and require calibration.

Percentage error = (measured value minus accepted value) divided by accepted value, multiplied by 100.

Fieldwork tools: quadrats estimate density and percentage cover, transects sample along a line, and capture-recapture estimates population size as (M times C) divided by R.

Contour lines join points of equal elevation; close spacing indicates steep slopes, and rivers flow downhill perpendicular to contours.

A climograph plots monthly temperature as a line and monthly rainfall as bars, allowing climate classification and comparison between sites.

Earth's four spheres are the geosphere, atmosphere, hydrosphere, and biosphere; matter and energy move between them, so a change in one sphere alters the others.

Two energy sources drive Earth systems: internal heat from radioactive decay and primordial heat drives tectonics and volcanism; solar radiation drives climate, weather, and the water cycle.

The rock cycle transforms material among igneous, sedimentary, and metamorphic rock through melting, cooling, weathering, erosion, deposition, compaction, and metamorphism.

In the water cycle, evaporation and transpiration absorb latent heat while condensation releases it, which transfers energy from the surface into the atmosphere.

The carbon cycle exchanges carbon between the atmosphere, oceans, biosphere, soils, and rocks; photosynthesis and ocean uptake remove carbon dioxide and combustion and respiration release it.

The nitrogen cycle requires fixation by lightning and bacteria, then nitrification, assimilation, and denitrification; nitrogen is commonly the limiting nutrient in ecosystems.

Positive feedbacks amplify change (ice-albedo loss reduces reflection and increases warming); negative feedbacks stabilise systems (more evaporation producing more cloud cover).

Relative dating uses superposition, cross-cutting relationships, and fossil correlation; absolute dating uses radiometric decay of isotopes such as carbon-14 and potassium-40.

Earth's internal structure: thin silicate crust, convective peridotite mantle, liquid iron-nickel outer core, and solid iron-nickel inner core; the Moho is the crust-mantle boundary.

Divergent boundaries create new oceanic crust at mid-ocean ridges; convergent boundaries produce subduction zones with trenches, volcanic arcs, or collision fold mountains; transform boundaries produce lateral faulting.

Evidence for plate tectonics includes symmetrical magnetic stripes on the seafloor, increasing crustal age away from ridges, matching continental fossils and rock sequences, and earthquake and volcano distribution.

Igneous rocks crystallise from magma; slow cooling at depth gives coarse-grained intrusive rocks (granite, gabbro) and rapid cooling at the surface gives fine-grained extrusive rocks (basalt, rhyolite).

Sedimentary rocks form by compaction and cementation of weathered and eroded sediment, preserving fossils and cross-bedding that record past environments and relative age.

Metamorphic rocks form under heat and pressure; foliated types (schist, gneiss) align minerals in bands, while non-foliated types (marble, quartzite) do not.

Ore deposits are non-renewable and viable only when grade, depth, and location make extraction economic; mining produces tailings, acid mine drainage, and land disturbance.

Fossil fuels form from buried organic matter under heat and pressure over millions of years: coal from terrestrial plants, oil and gas from marine plankton and algae.

Dry air is about 78% nitrogen, 21% oxygen, 0.93% argon, and 0.04% carbon dioxide, with variable water vapour; ozone concentrates in the stratosphere.

The greenhouse effect occurs because gases such as water vapour, carbon dioxide, methane, nitrous oxide, and CFCs absorb outgoing longwave radiation and re-emit it, warming the surface.

Temperature decreases with altitude in the troposphere at about 6.5 degrees C per km and increases in the stratosphere because ozone absorbs ultraviolet radiation.

The Coriolis effect deflects moving air and water to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, and is zero at the equator.

Global circulation cells (Hadley, Ferrel, and Polar) and associated pressure belts create prevailing winds and explain wet equatorial and dry subtropical climate zones.

Ocean currents are driven by wind and by density differences from temperature and salinity; surface currents redistribute heat and coastal upwelling brings nutrient-rich deep water to the surface.

The El Nino-Southern Oscillation shifts Pacific pressure and current patterns, bringing drought to eastern Australia and heavy rain to the eastern Pacific during El Nino.

Relative humidity is the ratio of actual water vapour to the saturation capacity at that temperature; cooling air to its dew point causes condensation and cloud formation.

Ecosystems consist of interacting biotic components (producers, consumers, decomposers) and abiotic components (light, temperature, water, soil, nutrients).

Energy flows one way through trophic levels, with only about 10% transferred to the next level, so food chains rarely exceed four or five levels.

Photosynthesis is 6CO2 + 6H2O + light giving C6H12O6 + 6O2; respiration reverses this reaction to release energy for metabolism.

Carbon, nitrogen, and phosphorus cycle through ecosystems and are recycled, whereas energy is not recycled and must be continually supplied by the Sun.

Biodiversity includes genetic, species, and ecosystem diversity, and higher biodiversity generally increases ecosystem resilience to disturbance.

Population size changes through births, deaths, immigration, and emigration; carrying capacity is the maximum population an environment can sustain.

Symbiosis includes mutualism (both species benefit), commensalism (one benefits and the other is unaffected), and parasitism (one benefits and the host is harmed).

Adaptations are structural, behavioural, or physiological; Australian examples include sclerophyll leaves, seeds that germinate after fire, and nocturnal activity.

Eutrophication occurs when nutrient runoff triggers algal blooms; decomposition then depletes dissolved oxygen and creates hypoxic dead zones.

Dryland salinity results from rising water tables after land clearing and irrigation; management includes revegetation, drainage, and reduced irrigation.

Air quality is assessed using particulate matter (PM10, PM2.5), sulfur dioxide, nitrogen oxides, ozone, and carbon monoxide, compared against national standards.

Climate change mitigation reduces greenhouse gas sources or enhances sinks; adaptation adjusts human and natural systems to expected impacts.

Environmental impact assessment identifies, predicts, and mitigates impacts before approval; it involves scoping, baseline data, prediction, and monitoring.

Sustainability balances ecological, economic, and social needs; renewable resources must be harvested below their regeneration rate.

Introduced species and habitat fragmentation are major causes of biodiversity loss; conservation strategies include reserves, wildlife corridors, and captive breeding.

The waste hierarchy, from most to least preferred: avoid, reduce, reuse, recycle, recover energy, and dispose to landfill.

The independent variable is manipulated, the dependent variable is measured, and controlled variables are held constant to ensure a fair test.

Validity concerns whether a method measures what it claims to measure; reliability concerns whether repeated measurements give consistent results.

Accuracy is closeness to the true value; precision is closeness of repeated measurements to one another.

Random errors scatter results around the true value and are reduced by averaging; systematic errors shift all results in one direction and require calibration.

Percentage error = (measured value minus accepted value) divided by accepted value, multiplied by 100.

Fieldwork tools: quadrats estimate density and percentage cover, transects sample along a line, and capture-recapture estimates population size as (M times C) divided by R.

Contour lines join points of equal elevation; close spacing indicates steep slopes, and rivers flow downhill perpendicular to contours.

A climograph plots monthly temperature as a line and monthly rainfall as bars, allowing climate classification and comparison between sites.

Earth's four spheres are the geosphere, atmosphere, hydrosphere, and biosphere; matter and energy move between them, so a change in one sphere alters the others.

Two energy sources drive Earth systems: internal heat from radioactive decay and primordial heat drives tectonics and volcanism; solar radiation drives climate, weather, and the water cycle.

The rock cycle transforms material among igneous, sedimentary, and metamorphic rock through melting, cooling, weathering, erosion, deposition, compaction, and metamorphism.

In the water cycle, evaporation and transpiration absorb latent heat while condensation releases it, which transfers energy from the surface into the atmosphere.

The carbon cycle exchanges carbon between the atmosphere, oceans, biosphere, soils, and rocks; photosynthesis and ocean uptake remove carbon dioxide and combustion and respiration release it.

The nitrogen cycle requires fixation by lightning and bacteria, then nitrification, assimilation, and denitrification; nitrogen is commonly the limiting nutrient in ecosystems.

Positive feedbacks amplify change (ice-albedo loss reduces reflection and increases warming); negative feedbacks stabilise systems (more evaporation producing more cloud cover).

Relative dating uses superposition, cross-cutting relationships, and fossil correlation; absolute dating uses radiometric decay of isotopes such as carbon-14 and potassium-40.

Earth's internal structure: thin silicate crust, convective peridotite mantle, liquid iron-nickel outer core, and solid iron-nickel inner core; the Moho is the crust-mantle boundary.

Divergent boundaries create new oceanic crust at mid-ocean ridges; convergent boundaries produce subduction zones with trenches, volcanic arcs, or collision fold mountains; transform boundaries produce lateral faulting.

Evidence for plate tectonics includes symmetrical magnetic stripes on the seafloor, increasing crustal age away from ridges, matching continental fossils and rock sequences, and earthquake and volcano distribution.

Igneous rocks crystallise from magma; slow cooling at depth gives coarse-grained intrusive rocks (granite, gabbro) and rapid cooling at the surface gives fine-grained extrusive rocks (basalt, rhyolite).

Sedimentary rocks form by compaction and cementation of weathered and eroded sediment, preserving fossils and cross-bedding that record past environments and relative age.

Metamorphic rocks form under heat and pressure; foliated types (schist, gneiss) align minerals in bands, while non-foliated types (marble, quartzite) do not.

Ore deposits are non-renewable and viable only when grade, depth, and location make extraction economic; mining produces tailings, acid mine drainage, and land disturbance.

Fossil fuels form from buried organic matter under heat and pressure over millions of years: coal from terrestrial plants, oil and gas from marine plankton and algae.

Dry air is about 78% nitrogen, 21% oxygen, 0.93% argon, and 0.04% carbon dioxide, with variable water vapour; ozone concentrates in the stratosphere.

The greenhouse effect occurs because gases such as water vapour, carbon dioxide, methane, nitrous oxide, and CFCs absorb outgoing longwave radiation and re-emit it, warming the surface.

Temperature decreases with altitude in the troposphere at about 6.5 degrees C per km and increases in the stratosphere because ozone absorbs ultraviolet radiation.

The Coriolis effect deflects moving air and water to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, and is zero at the equator.

Global circulation cells (Hadley, Ferrel, and Polar) and associated pressure belts create prevailing winds and explain wet equatorial and dry subtropical climate zones.

Ocean currents are driven by wind and by density differences from temperature and salinity; surface currents redistribute heat and coastal upwelling brings nutrient-rich deep water to the surface.

The El Nino-Southern Oscillation shifts Pacific pressure and current patterns, bringing drought to eastern Australia and heavy rain to the eastern Pacific during El Nino.

Relative humidity is the ratio of actual water vapour to the saturation capacity at that temperature; cooling air to its dew point causes condensation and cloud formation.

Ecosystems consist of interacting biotic components (producers, consumers, decomposers) and abiotic components (light, temperature, water, soil, nutrients).

Energy flows one way through trophic levels, with only about 10% transferred to the next level, so food chains rarely exceed four or five levels.

Photosynthesis is 6CO2 + 6H2O + light giving C6H12O6 + 6O2; respiration reverses this reaction to release energy for metabolism.

Carbon, nitrogen, and phosphorus cycle through ecosystems and are recycled, whereas energy is not recycled and must be continually supplied by the Sun.

Biodiversity includes genetic, species, and ecosystem diversity, and higher biodiversity generally increases ecosystem resilience to disturbance.

Population size changes through births, deaths, immigration, and emigration; carrying capacity is the maximum population an environment can sustain.

Symbiosis includes mutualism (both species benefit), commensalism (one benefits and the other is unaffected), and parasitism (one benefits and the host is harmed).

Adaptations are structural, behavioural, or physiological; Australian examples include sclerophyll leaves, seeds that germinate after fire, and nocturnal activity.

Eutrophication occurs when nutrient runoff triggers algal blooms; decomposition then depletes dissolved oxygen and creates hypoxic dead zones.

Dryland salinity results from rising water tables after land clearing and irrigation; management includes revegetation, drainage, and reduced irrigation.

Air quality is assessed using particulate matter (PM10, PM2.5), sulfur dioxide, nitrogen oxides, ozone, and carbon monoxide, compared against national standards.

Climate change mitigation reduces greenhouse gas sources or enhances sinks; adaptation adjusts human and natural systems to expected impacts.

Environmental impact assessment identifies, predicts, and mitigates impacts before approval; it involves scoping, baseline data, prediction, and monitoring.

Sustainability balances ecological, economic, and social needs; renewable resources must be harvested below their regeneration rate.

Introduced species and habitat fragmentation are major causes of biodiversity loss; conservation strategies include reserves, wildlife corridors, and captive breeding.

The waste hierarchy, from most to least preferred: avoid, reduce, reuse, recycle, recover energy, and dispose to landfill.

The independent variable is manipulated, the dependent variable is measured, and controlled variables are held constant to ensure a fair test.

Validity concerns whether a method measures what it claims to measure; reliability concerns whether repeated measurements give consistent results.

Accuracy is closeness to the true value; precision is closeness of repeated measurements to one another.

Random errors scatter results around the true value and are reduced by averaging; systematic errors shift all results in one direction and require calibration.

Percentage error = (measured value minus accepted value) divided by accepted value, multiplied by 100.

Fieldwork tools: quadrats estimate density and percentage cover, transects sample along a line, and capture-recapture estimates population size as (M times C) divided by R.

Contour lines join points of equal elevation; close spacing indicates steep slopes, and rivers flow downhill perpendicular to contours.

A climograph plots monthly temperature as a line and monthly rainfall as bars, allowing climate classification and comparison between sites.

Earth's four spheres are the geosphere, atmosphere, hydrosphere, and biosphere; matter and energy move between them, so a change in one sphere alters the others.

Two energy sources drive Earth systems: internal heat from radioactive decay and primordial heat drives tectonics and volcanism; solar radiation drives climate, weather, and the water cycle.

The rock cycle transforms material among igneous, sedimentary, and metamorphic rock through melting, cooling, weathering, erosion, deposition, compaction, and metamorphism.

In the water cycle, evaporation and transpiration absorb latent heat while condensation releases it, which transfers energy from the surface into the atmosphere.

The carbon cycle exchanges carbon between the atmosphere, oceans, biosphere, soils, and rocks; photosynthesis and ocean uptake remove carbon dioxide and combustion and respiration release it.

The nitrogen cycle requires fixation by lightning and bacteria, then nitrification, assimilation, and denitrification; nitrogen is commonly the limiting nutrient in ecosystems.

Positive feedbacks amplify change (ice-albedo loss reduces reflection and increases warming); negative feedbacks stabilise systems (more evaporation producing more cloud cover).

Relative dating uses superposition, cross-cutting relationships, and fossil correlation; absolute dating uses radiometric decay of isotopes such as carbon-14 and potassium-40.

Earth's internal structure: thin silicate crust, convective peridotite mantle, liquid iron-nickel outer core, and solid iron-nickel inner core; the Moho is the crust-mantle boundary.

Divergent boundaries create new oceanic crust at mid-ocean ridges; convergent boundaries produce subduction zones with trenches, volcanic arcs, or collision fold mountains; transform boundaries produce lateral faulting.

Evidence for plate tectonics includes symmetrical magnetic stripes on the seafloor, increasing crustal age away from ridges, matching continental fossils and rock sequences, and earthquake and volcano distribution.

Igneous rocks crystallise from magma; slow cooling at depth gives coarse-grained intrusive rocks (granite, gabbro) and rapid cooling at the surface gives fine-grained extrusive rocks (basalt, rhyolite).

Sedimentary rocks form by compaction and cementation of weathered and eroded sediment, preserving fossils and cross-bedding that record past environments and relative age.

Metamorphic rocks form under heat and pressure; foliated types (schist, gneiss) align minerals in bands, while non-foliated types (marble, quartzite) do not.

Ore deposits are non-renewable and viable only when grade, depth, and location make extraction economic; mining produces tailings, acid mine drainage, and land disturbance.

Fossil fuels form from buried organic matter under heat and pressure over millions of years: coal from terrestrial plants, oil and gas from marine plankton and algae.

Dry air is about 78% nitrogen, 21% oxygen, 0.93% argon, and 0.04% carbon dioxide, with variable water vapour; ozone concentrates in the stratosphere.

The greenhouse effect occurs because gases such as water vapour, carbon dioxide, methane, nitrous oxide, and CFCs absorb outgoing longwave radiation and re-emit it, warming the surface.

Temperature decreases with altitude in the troposphere at about 6.5 degrees C per km and increases in the stratosphere because ozone absorbs ultraviolet radiation.

The Coriolis effect deflects moving air and water to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, and is zero at the equator.

Global circulation cells (Hadley, Ferrel, and Polar) and associated pressure belts create prevailing winds and explain wet equatorial and dry subtropical climate zones.

Ocean currents are driven by wind and by density differences from temperature and salinity; surface currents redistribute heat and coastal upwelling brings nutrient-rich deep water to the surface.

The El Nino-Southern Oscillation shifts Pacific pressure and current patterns, bringing drought to eastern Australia and heavy rain to the eastern Pacific during El Nino.

Relative humidity is the ratio of actual water vapour to the saturation capacity at that temperature; cooling air to its dew point causes condensation and cloud formation.

Ecosystems consist of interacting biotic components (producers, consumers, decomposers) and abiotic components (light, temperature, water, soil, nutrients).

Energy flows one way through trophic levels, with only about 10% transferred to the next level, so food chains rarely exceed four or five levels.

Photosynthesis is 6CO2 + 6H2O + light giving C6H12O6 + 6O2; respiration reverses this reaction to release energy for metabolism.

Carbon, nitrogen, and phosphorus cycle through ecosystems and are recycled, whereas energy is not recycled and must be continually supplied by the Sun.

Biodiversity includes genetic, species, and ecosystem diversity, and higher biodiversity generally increases ecosystem resilience to disturbance.

Population size changes through births, deaths, immigration, and emigration; carrying capacity is the maximum population an environment can sustain.

Symbiosis includes mutualism (both species benefit), commensalism (one benefits and the other is unaffected), and parasitism (one benefits and the host is harmed).

Adaptations are structural, behavioural, or physiological; Australian examples include sclerophyll leaves, seeds that germinate after fire, and nocturnal activity.

Eutrophication occurs when nutrient runoff triggers algal blooms; decomposition then depletes dissolved oxygen and creates hypoxic dead zones.

Dryland salinity results from rising water tables after land clearing and irrigation; management includes revegetation, drainage, and reduced irrigation.

Air quality is assessed using particulate matter (PM10, PM2.5), sulfur dioxide, nitrogen oxides, ozone, and carbon monoxide, compared against national standards.

Climate change mitigation reduces greenhouse gas sources or enhances sinks; adaptation adjusts human and natural systems to expected impacts.

Environmental impact assessment identifies, predicts, and mitigates impacts before approval; it involves scoping, baseline data, prediction, and monitoring.

Sustainability balances ecological, economic, and social needs; renewable resources must be harvested below their regeneration rate.

Introduced species and habitat fragmentation are major causes of biodiversity loss; conservation strategies include reserves, wildlife corridors, and captive breeding.

The waste hierarchy, from most to least preferred: avoid, reduce, reuse, recycle, recover energy, and dispose to landfill.

The independent variable is manipulated, the dependent variable is measured, and controlled variables are held constant to ensure a fair test.

Validity concerns whether a method measures what it claims to measure; reliability concerns whether repeated measurements give consistent results.

Accuracy is closeness to the true value; precision is closeness of repeated measurements to one another.

Random errors scatter results around the true value and are reduced by averaging; systematic errors shift all results in one direction and require calibration.

Percentage error = (measured value minus accepted value) divided by accepted value, multiplied by 100.

Fieldwork tools: quadrats estimate density and percentage cover, transects sample along a line, and capture-recapture estimates population size as (M times C) divided by R.

Contour lines join points of equal elevation; close spacing indicates steep slopes, and rivers flow downhill perpendicular to contours.

A climograph plots monthly temperature as a line and monthly rainfall as bars, allowing climate classification and comparison between sites.

Earth's four spheres are the geosphere, atmosphere, hydrosphere, and biosphere; matter and energy move between them, so a change in one sphere alters the others.

Two energy sources drive Earth systems: internal heat from radioactive decay and primordial heat drives tectonics and volcanism; solar radiation drives climate, weather, and the water cycle.

The rock cycle transforms material among igneous, sedimentary, and metamorphic rock through melting, cooling, weathering, erosion, deposition, compaction, and metamorphism.

In the water cycle, evaporation and transpiration absorb latent heat while condensation releases it, which transfers energy from the surface into the atmosphere.

The carbon cycle exchanges carbon between the atmosphere, oceans, biosphere, soils, and rocks; photosynthesis and ocean uptake remove carbon dioxide and combustion and respiration release it.

The nitrogen cycle requires fixation by lightning and bacteria, then nitrification, assimilation, and denitrification; nitrogen is commonly the limiting nutrient in ecosystems.

Positive feedbacks amplify change (ice-albedo loss reduces reflection and increases warming); negative feedbacks stabilise systems (more evaporation producing more cloud cover).

Relative dating uses superposition, cross-cutting relationships, and fossil correlation; absolute dating uses radiometric decay of isotopes such as carbon-14 and potassium-40.

Earth's internal structure: thin silicate crust, convective peridotite mantle, liquid iron-nickel outer core, and solid iron-nickel inner core; the Moho is the crust-mantle boundary.

Divergent boundaries create new oceanic crust at mid-ocean ridges; convergent boundaries produce subduction zones with trenches, volcanic arcs, or collision fold mountains; transform boundaries produce lateral faulting.

Evidence for plate tectonics includes symmetrical magnetic stripes on the seafloor, increasing crustal age away from ridges, matching continental fossils and rock sequences, and earthquake and volcano distribution.

Igneous rocks crystallise from magma; slow cooling at depth gives coarse-grained intrusive rocks (granite, gabbro) and rapid cooling at the surface gives fine-grained extrusive rocks (basalt, rhyolite).

Sedimentary rocks form by compaction and cementation of weathered and eroded sediment, preserving fossils and cross-bedding that record past environments and relative age.

Metamorphic rocks form under heat and pressure; foliated types (schist, gneiss) align minerals in bands, while non-foliated types (marble, quartzite) do not.

Ore deposits are non-renewable and viable only when grade, depth, and location make extraction economic; mining produces tailings, acid mine drainage, and land disturbance.

Fossil fuels form from buried organic matter under heat and pressure over millions of years: coal from terrestrial plants, oil and gas from marine plankton and algae.

Dry air is about 78% nitrogen, 21% oxygen, 0.93% argon, and 0.04% carbon dioxide, with variable water vapour; ozone concentrates in the stratosphere.

The greenhouse effect occurs because gases such as water vapour, carbon dioxide, methane, nitrous oxide, and CFCs absorb outgoing longwave radiation and re-emit it, warming the surface.

Temperature decreases with altitude in the troposphere at about 6.5 degrees C per km and increases in the stratosphere because ozone absorbs ultraviolet radiation.

The Coriolis effect deflects moving air and water to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, and is zero at the equator.

Global circulation cells (Hadley, Ferrel, and Polar) and associated pressure belts create prevailing winds and explain wet equatorial and dry subtropical climate zones.

Ocean currents are driven by wind and by density differences from temperature and salinity; surface currents redistribute heat and coastal upwelling brings nutrient-rich deep water to the surface.

The El Nino-Southern Oscillation shifts Pacific pressure and current patterns, bringing drought to eastern Australia and heavy rain to the eastern Pacific during El Nino.

Relative humidity is the ratio of actual water vapour to the saturation capacity at that temperature; cooling air to its dew point causes condensation and cloud formation.

Ecosystems consist of interacting biotic components (producers, consumers, decomposers) and abiotic components (light, temperature, water, soil, nutrients).

Energy flows one way through trophic levels, with only about 10% transferred to the next level, so food chains rarely exceed four or five levels.

Photosynthesis is 6CO2 + 6H2O + light giving C6H12O6 + 6O2; respiration reverses this reaction to release energy for metabolism.

Carbon, nitrogen, and phosphorus cycle through ecosystems and are recycled, whereas energy is not recycled and must be continually supplied by the Sun.

Biodiversity includes genetic, species, and ecosystem diversity, and higher biodiversity generally increases ecosystem resilience to disturbance.

Population size changes through births, deaths, immigration, and emigration; carrying capacity is the maximum population an environment can sustain.

Symbiosis includes mutualism (both species benefit), commensalism (one benefits and the other is unaffected), and parasitism (one benefits and the host is harmed).

Adaptations are structural, behavioural, or physiological; Australian examples include sclerophyll leaves, seeds that germinate after fire, and nocturnal activity.

Eutrophication occurs when nutrient runoff triggers algal blooms; decomposition then depletes dissolved oxygen and creates hypoxic dead zones.

Dryland salinity results from rising water tables after land clearing and irrigation; management includes revegetation, drainage, and reduced irrigation.

Air quality is assessed using particulate matter (PM10, PM2.5), sulfur dioxide, nitrogen oxides, ozone, and carbon monoxide, compared against national standards.

Climate change mitigation reduces greenhouse gas sources or enhances sinks; adaptation adjusts human and natural systems to expected impacts.

Environmental impact assessment identifies, predicts, and mitigates impacts before approval; it involves scoping, baseline data, prediction, and monitoring.

Sustainability balances ecological, economic, and social needs; renewable resources must be harvested below their regeneration rate.

Introduced species and habitat fragmentation are major causes of biodiversity loss; conservation strategies include reserves, wildlife corridors, and captive breeding.

The waste hierarchy, from most to least preferred: avoid, reduce, reuse, recycle, recover energy, and dispose to landfill.

The independent variable is manipulated, the dependent variable is measured, and controlled variables are held constant to ensure a fair test.

Validity concerns whether a method measures what it claims to measure; reliability concerns whether repeated measurements give consistent results.

Accuracy is closeness to the true value; precision is closeness of repeated measurements to one another.

Random errors scatter results around the true value and are reduced by averaging; systematic errors shift all results in one direction and require calibration.

Percentage error = (measured value minus accepted value) divided by accepted value, multiplied by 100.

Fieldwork tools: quadrats estimate density and percentage cover, transects sample along a line, and capture-recapture estimates population size as (M times C) divided by R.

Contour lines join points of equal elevation; close spacing indicates steep slopes, and rivers flow downhill perpendicular to contours.

A climograph plots monthly temperature as a line and monthly rainfall as bars, allowing climate classification and comparison between sites.

Earth's four spheres are the geosphere, atmosphere, hydrosphere, and biosphere; matter and energy move between them, so a change in one sphere alters the others.

Two energy sources drive Earth systems: internal heat from radioactive decay and primordial heat drives tectonics and volcanism; solar radiation drives climate, weather, and the water cycle.

The rock cycle transforms material among igneous, sedimentary, and metamorphic rock through melting, cooling, weathering, erosion, deposition, compaction, and metamorphism.

In the water cycle, evaporation and transpiration absorb latent heat while condensation releases it, which transfers energy from the surface into the atmosphere.

The carbon cycle exchanges carbon between the atmosphere, oceans, biosphere, soils, and rocks; photosynthesis and ocean uptake remove carbon dioxide and combustion and respiration release it.

The nitrogen cycle requires fixation by lightning and bacteria, then nitrification, assimilation, and denitrification; nitrogen is commonly the limiting nutrient in ecosystems.

Positive feedbacks amplify change (ice-albedo loss reduces reflection and increases warming); negative feedbacks stabilise systems (more evaporation producing more cloud cover).

Relative dating uses superposition, cross-cutting relationships, and fossil correlation; absolute dating uses radiometric decay of isotopes such as carbon-14 and potassium-40.

Earth's internal structure: thin silicate crust, convective peridotite mantle, liquid iron-nickel outer core, and solid iron-nickel inner core; the Moho is the crust-mantle boundary.

Divergent boundaries create new oceanic crust at mid-ocean ridges; convergent boundaries produce subduction zones with trenches, volcanic arcs, or collision fold mountains; transform boundaries produce lateral faulting.

Evidence for plate tectonics includes symmetrical magnetic stripes on the seafloor, increasing crustal age away from ridges, matching continental fossils and rock sequences, and earthquake and volcano distribution.

Igneous rocks crystallise from magma; slow cooling at depth gives coarse-grained intrusive rocks (granite, gabbro) and rapid cooling at the surface gives fine-grained extrusive rocks (basalt, rhyolite).

Sedimentary rocks form by compaction and cementation of weathered and eroded sediment, preserving fossils and cross-bedding that record past environments and relative age.

Metamorphic rocks form under heat and pressure; foliated types (schist, gneiss) align minerals in bands, while non-foliated types (marble, quartzite) do not.

Ore deposits are non-renewable and viable only when grade, depth, and location make extraction economic; mining produces tailings, acid mine drainage, and land disturbance.

Fossil fuels form from buried organic matter under heat and pressure over millions of years: coal from terrestrial plants, oil and gas from marine plankton and algae.

Dry air is about 78% nitrogen, 21% oxygen, 0.93% argon, and 0.04% carbon dioxide, with variable water vapour; ozone concentrates in the stratosphere.

The greenhouse effect occurs because gases such as water vapour, carbon dioxide, methane, nitrous oxide, and CFCs absorb outgoing longwave radiation and re-emit it, warming the surface.

Temperature decreases with altitude in the troposphere at about 6.5 degrees C per km and increases in the stratosphere because ozone absorbs ultraviolet radiation.

The Coriolis effect deflects moving air and water to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, and is zero at the equator.

Global circulation cells (Hadley, Ferrel, and Polar) and associated pressure belts create prevailing winds and explain wet equatorial and dry subtropical climate zones.

Ocean currents are driven by wind and by density differences from temperature and salinity; surface currents redistribute heat and coastal upwelling brings nutrient-rich deep water to the surface.

The El Nino-Southern Oscillation shifts Pacific pressure and current patterns, bringing drought to eastern Australia and heavy rain to the eastern Pacific during El Nino.

Relative humidity is the ratio of actual water vapour to the saturation capacity at that temperature; cooling air to its dew point causes condensation and cloud formation.

Ecosystems consist of interacting biotic components (producers, consumers, decomposers) and abiotic components (light, temperature, water, soil, nutrients).

Energy flows one way through trophic levels, with only about 10% transferred to the next level, so food chains rarely exceed four or five levels.

Photosynthesis is 6CO2 + 6H2O + light giving C6H12O6 + 6O2; respiration reverses this reaction to release energy for metabolism.

Carbon, nitrogen, and phosphorus cycle through ecosystems and are recycled, whereas energy is not recycled and must be continually supplied by the Sun.

Biodiversity includes genetic, species, and ecosystem diversity, and higher biodiversity generally increases ecosystem resilience to disturbance.

Population size changes through births, deaths, immigration, and emigration; carrying capacity is the maximum population an environment can sustain.

Symbiosis includes mutualism (both species benefit), commensalism (one benefits and the other is unaffected), and parasitism (one benefits and the host is harmed).

Adaptations are structural, behavioural, or physiological; Australian examples include sclerophyll leaves, seeds that germinate after fire, and nocturnal activity.

Eutrophication occurs when nutrient runoff triggers algal blooms; decomposition then depletes dissolved oxygen and creates hypoxic dead zones.

Dryland salinity results from rising water tables after land clearing and irrigation; management includes revegetation, drainage, and reduced irrigation.

Air quality is assessed using particulate matter (PM10, PM2.5), sulfur dioxide, nitrogen oxides, ozone, and carbon monoxide, compared against national standards.

Climate change mitigation reduces greenhouse gas sources or enhances sinks; adaptation adjusts human and natural systems to expected impacts.

Environmental impact assessment identifies, predicts, and mitigates impacts before approval; it involves scoping, baseline data, prediction, and monitoring.

Sustainability balances ecological, economic, and social needs; renewable resources must be harvested below their regeneration rate.

Introduced species and habitat fragmentation are major causes of biodiversity loss; conservation strategies include reserves, wildlife corridors, and captive breeding.

The waste hierarchy, from most to least preferred: avoid, reduce, reuse, recycle, recover energy, and dispose to landfill.

The independent variable is manipulated, the dependent variable is measured, and controlled variables are held constant to ensure a fair test.

Validity concerns whether a method measures what it claims to measure; reliability concerns whether repeated measurements give consistent results.

Accuracy is closeness to the true value; precision is closeness of repeated measurements to one another.

Random errors scatter results around the true value and are reduced by averaging; systematic errors shift all results in one direction and require calibration.

Percentage error = (measured value minus accepted value) divided by accepted value, multiplied by 100.

Fieldwork tools: quadrats estimate density and percentage cover, transects sample along a line, and capture-recapture estimates population size as (M times C) divided by R.

Contour lines join points of equal elevation; close spacing indicates steep slopes, and rivers flow downhill perpendicular to contours.

A climograph plots monthly temperature as a line and monthly rainfall as bars, allowing climate classification and comparison between sites.

Earth's four spheres are the geosphere, atmosphere, hydrosphere, and biosphere; matter and energy move between them, so a change in one sphere alters the others.

Two energy sources drive Earth systems: internal heat from radioactive decay and primordial heat drives tectonics and volcanism; solar radiation drives climate, weather, and the water cycle.

The rock cycle transforms material among igneous, sedimentary, and metamorphic rock through melting, cooling, weathering, erosion, deposition, compaction, and metamorphism.

In the water cycle, evaporation and transpiration absorb latent heat while condensation releases it, which transfers energy from the surface into the atmosphere.

The carbon cycle exchanges carbon between the atmosphere, oceans, biosphere, soils, and rocks; photosynthesis and ocean uptake remove carbon dioxide and combustion and respiration release it.

The nitrogen cycle requires fixation by lightning and bacteria, then nitrification, assimilation, and denitrification; nitrogen is commonly the limiting nutrient in ecosystems.

Positive feedbacks amplify change (ice-albedo loss reduces reflection and increases warming); negative feedbacks stabilise systems (more evaporation producing more cloud cover).

Relative dating uses superposition, cross-cutting relationships, and fossil correlation; absolute dating uses radiometric decay of isotopes such as carbon-14 and potassium-40.

Earth's internal structure: thin silicate crust, convective peridotite mantle, liquid iron-nickel outer core, and solid iron-nickel inner core; the Moho is the crust-mantle boundary.

Divergent boundaries create new oceanic crust at mid-ocean ridges; convergent boundaries produce subduction zones with trenches, volcanic arcs, or collision fold mountains; transform boundaries produce lateral faulting.

Evidence for plate tectonics includes symmetrical magnetic stripes on the seafloor, increasing crustal age away from ridges, matching continental fossils and rock sequences, and earthquake and volcano distribution.

Igneous rocks crystallise from magma; slow cooling at depth gives coarse-grained intrusive rocks (granite, gabbro) and rapid cooling at the surface gives fine-grained extrusive rocks (basalt, rhyolite).

Sedimentary rocks form by compaction and cementation of weathered and eroded sediment, preserving fossils and cross-bedding that record past environments and relative age.

Metamorphic rocks form under heat and pressure; foliated types (schist, gneiss) align minerals in bands, while non-foliated types (marble, quartzite) do not.

Ore deposits are non-renewable and viable only when grade, depth, and location make extraction economic; mining produces tailings, acid mine drainage, and land disturbance.

Fossil fuels form from buried organic matter under heat and pressure over millions of years: coal from terrestrial plants, oil and gas from marine plankton and algae.

Dry air is about 78% nitrogen, 21% oxygen, 0.93% argon, and 0.04% carbon dioxide, with variable water vapour; ozone concentrates in the stratosphere.

The greenhouse effect occurs because gases such as water vapour, carbon dioxide, methane, nitrous oxide, and CFCs absorb outgoing longwave radiation and re-emit it, warming the surface.

Temperature decreases with altitude in the troposphere at about 6.5 degrees C per km and increases in the stratosphere because ozone absorbs ultraviolet radiation.

The Coriolis effect deflects moving air and water to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, and is zero at the equator.

Global circulation cells (Hadley, Ferrel, and Polar) and associated pressure belts create prevailing winds and explain wet equatorial and dry subtropical climate zones.

Ocean currents are driven by wind and by density differences from temperature and salinity; surface currents redistribute heat and coastal upwelling brings nutrient-rich deep water to the surface.

The El Nino-Southern Oscillation shifts Pacific pressure and current patterns, bringing drought to eastern Australia and heavy rain to the eastern Pacific during El Nino.

Relative humidity is the ratio of actual water vapour to the saturation capacity at that temperature; cooling air to its dew point causes condensation and cloud formation.

Ecosystems consist of interacting biotic components (producers, consumers, decomposers) and abiotic components (light, temperature, water, soil, nutrients).

Energy flows one way through trophic levels, with only about 10% transferred to the next level, so food chains rarely exceed four or five levels.

Photosynthesis is 6CO2 + 6H2O + light giving C6H12O6 + 6O2; respiration reverses this reaction to release energy for metabolism.

Carbon, nitrogen, and phosphorus cycle through ecosystems and are recycled, whereas energy is not recycled and must be continually supplied by the Sun.

Biodiversity includes genetic, species, and ecosystem diversity, and higher biodiversity generally increases ecosystem resilience to disturbance.

Population size changes through births, deaths, immigration, and emigration; carrying capacity is the maximum population an environment can sustain.

Symbiosis includes mutualism (both species benefit), commensalism (one benefits and the other is unaffected), and parasitism (one benefits and the host is harmed).

Adaptations are structural, behavioural, or physiological; Australian examples include sclerophyll leaves, seeds that germinate after fire, and nocturnal activity.

Eutrophication occurs when nutrient runoff triggers algal blooms; decomposition then depletes dissolved oxygen and creates hypoxic dead zones.

Dryland salinity results from rising water tables after land clearing and irrigation; management includes revegetation, drainage, and reduced irrigation.

Air quality is assessed using particulate matter (PM10, PM2.5), sulfur dioxide, nitrogen oxides, ozone, and carbon monoxide, compared against national standards.

Climate change mitigation reduces greenhouse gas sources or enhances sinks; adaptation adjusts human and natural systems to expected impacts.

Environmental impact assessment identifies, predicts, and mitigates impacts before approval; it involves scoping, baseline data, prediction, and monitoring.

Sustainability balances ecological, economic, and social needs; renewable resources must be harvested below their regeneration rate.

Introduced species and habitat fragmentation are major causes of biodiversity loss; conservation strategies include reserves, wildlife corridors, and captive breeding.

The waste hierarchy, from most to least preferred: avoid, reduce, reuse, recycle, recover energy, and dispose to landfill.

The independent variable is manipulated, the dependent variable is measured, and controlled variables are held constant to ensure a fair test.

Validity concerns whether a method measures what it claims to measure; reliability concerns whether repeated measurements give consistent results.

Accuracy is closeness to the true value; precision is closeness of repeated measurements to one another.

Random errors scatter results around the true value and are reduced by averaging; systematic errors shift all results in one direction and require calibration.

Percentage error = (measured value minus accepted value) divided by accepted value, multiplied by 100.

Fieldwork tools: quadrats estimate density and percentage cover, transects sample along a line, and capture-recapture estimates population size as (M times C) divided by R.

Contour lines join points of equal elevation; close spacing indicates steep slopes, and rivers flow downhill perpendicular to contours.

A climograph plots monthly temperature as a line and monthly rainfall as bars, allowing climate classification and comparison between sites.

Earth's four spheres are the geosphere, atmosphere, hydrosphere, and biosphere; matter and energy move between them, so a change in one sphere alters the others.

Two energy sources drive Earth systems: internal heat from radioactive decay and primordial heat drives tectonics and volcanism; solar radiation drives climate, weather, and the water cycle.

The rock cycle transforms material among igneous, sedimentary, and metamorphic rock through melting, cooling, weathering, erosion, deposition, compaction, and metamorphism.

In the water cycle, evaporation and transpiration absorb latent heat while condensation releases it, which transfers energy from the surface into the atmosphere.

The carbon cycle exchanges carbon between the atmosphere, oceans, biosphere, soils, and rocks; photosynthesis and ocean uptake remove carbon dioxide and combustion and respiration release it.

The nitrogen cycle requires fixation by lightning and bacteria, then nitrification, assimilation, and denitrification; nitrogen is commonly the limiting nutrient in ecosystems.

Positive feedbacks amplify change (ice-albedo loss reduces reflection and increases warming); negative feedbacks stabilise systems (more evaporation producing more cloud cover).

Relative dating uses superposition, cross-cutting relationships, and fossil correlation; absolute dating uses radiometric decay of isotopes such as carbon-14 and potassium-40.

Earth's internal structure: thin silicate crust, convective peridotite mantle, liquid iron-nickel outer core, and solid iron-nickel inner core; the Moho is the crust-mantle boundary.

Divergent boundaries create new oceanic crust at mid-ocean ridges; convergent boundaries produce subduction zones with trenches, volcanic arcs, or collision fold mountains; transform boundaries produce lateral faulting.

Evidence for plate tectonics includes symmetrical magnetic stripes on the seafloor, increasing crustal age away from ridges, matching continental fossils and rock sequences, and earthquake and volcano distribution.

Igneous rocks crystallise from magma; slow cooling at depth gives coarse-grained intrusive rocks (granite, gabbro) and rapid cooling at the surface gives fine-grained extrusive rocks (basalt, rhyolite).

Sedimentary rocks form by compaction and cementation of weathered and eroded sediment, preserving fossils and cross-bedding that record past environments and relative age.

Metamorphic rocks form under heat and pressure; foliated types (schist, gneiss) align minerals in bands, while non-foliated types (marble, quartzite) do not.

Ore deposits are non-renewable and viable only when grade, depth, and location make extraction economic; mining produces tailings, acid mine drainage, and land disturbance.

Fossil fuels form from buried organic matter under heat and pressure over millions of years: coal from terrestrial plants, oil and gas from marine plankton and algae.

Dry air is about 78% nitrogen, 21% oxygen, 0.93% argon, and 0.04% carbon dioxide, with variable water vapour; ozone concentrates in the stratosphere.

The greenhouse effect occurs because gases such as water vapour, carbon dioxide, methane, nitrous oxide, and CFCs absorb outgoing longwave radiation and re-emit it, warming the surface.

Temperature decreases with altitude in the troposphere at about 6.5 degrees C per km and increases in the stratosphere because ozone absorbs ultraviolet radiation.

The Coriolis effect deflects moving air and water to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, and is zero at the equator.

Global circulation cells (Hadley, Ferrel, and Polar) and associated pressure belts create prevailing winds and explain wet equatorial and dry subtropical climate zones.

Ocean currents are driven by wind and by density differences from temperature and salinity; surface currents redistribute heat and coastal upwelling brings nutrient-rich deep water to the surface.

The El Nino-Southern Oscillation shifts Pacific pressure and current patterns, bringing drought to eastern Australia and heavy rain to the eastern Pacific during El Nino.

Relative humidity is the ratio of actual water vapour to the saturation capacity at that temperature; cooling air to its dew point causes condensation and cloud formation.

Ecosystems consist of interacting biotic components (producers, consumers, decomposers) and abiotic components (light, temperature, water, soil, nutrients).

Energy flows one way through trophic levels, with only about 10% transferred to the next level, so food chains rarely exceed four or five levels.

Photosynthesis is 6CO2 + 6H2O + light giving C6H12O6 + 6O2; respiration reverses this reaction to release energy for metabolism.

Carbon, nitrogen, and phosphorus cycle through ecosystems and are recycled, whereas energy is not recycled and must be continually supplied by the Sun.

Biodiversity includes genetic, species, and ecosystem diversity, and higher biodiversity generally increases ecosystem resilience to disturbance.

Population size changes through births, deaths, immigration, and emigration; carrying capacity is the maximum population an environment can sustain.

Symbiosis includes mutualism (both species benefit), commensalism (one benefits and the other is unaffected), and parasitism (one benefits and the host is harmed).

Adaptations are structural, behavioural, or physiological; Australian examples include sclerophyll leaves, seeds that germinate after fire, and nocturnal activity.

Eutrophication occurs when nutrient runoff triggers algal blooms; decomposition then depletes dissolved oxygen and creates hypoxic dead zones.

Dryland salinity results from rising water tables after land clearing and irrigation; management includes revegetation, drainage, and reduced irrigation.

Air quality is assessed using particulate matter (PM10, PM2.5), sulfur dioxide, nitrogen oxides, ozone, and carbon monoxide, compared against national standards.

Climate change mitigation reduces greenhouse gas sources or enhances sinks; adaptation adjusts human and natural systems to expected impacts.

Environmental impact assessment identifies, predicts, and mitigates impacts before approval; it involves scoping, baseline data, prediction, and monitoring.

Sustainability balances ecological, economic, and social needs; renewable resources must be harvested below their regeneration rate.

Introduced species and habitat fragmentation are major causes of biodiversity loss; conservation strategies include reserves, wildlife corridors, and captive breeding.

The waste hierarchy, from most to least preferred: avoid, reduce, reuse, recycle, recover energy, and dispose to landfill.

The independent variable is manipulated, the dependent variable is measured, and controlled variables are held constant to ensure a fair test.

Validity concerns whether a method measures what it claims to measure; reliability concerns whether repeated measurements give consistent results.

Accuracy is closeness to the true value; precision is closeness of repeated measurements to one another.

Random errors scatter results around the true value and are reduced by averaging; systematic errors shift all results in one direction and require calibration.

Percentage error = (measured value minus accepted value) divided by accepted value, multiplied by 100.

Fieldwork tools: quadrats estimate density and percentage cover, transects sample along a line, and capture-recapture estimates population size as (M times C) divided by R.

Contour lines join points of equal elevation; close spacing indicates steep slopes, and rivers flow downhill perpendicular to contours.

A climograph plots monthly temperature as a line and monthly rainfall as bars, allowing climate classification and comparison between sites.