QCAA Earth & Environmental Science flashcards
QCAA Earth & Environmental Science · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Biodiversity
- The variety of life at three levels: genetic diversity within species, species diversity within communities, and ecosystem diversity across landscapes.
- Species richness
- The number of different species present in a defined area or sample, counted without regard to how many individuals each species contributes.
- Species evenness
- A measure of how similar species abundances are within a community; high evenness means species are represented in comparable numbers.
- Simpson's diversity index
- Calculated as 1 minus the sum of squared proportional abundances. Values near 1 indicate high diversity; near 0 indicates one species dominates.
- Shannon–Wiener index
- A diversity index computed as minus the sum of pᵢ ln pᵢ, where pᵢ is each species' proportional abundance. It is sensitive to rare species.
- Primary succession
- Succession beginning on newly formed substrate with no existing soil or seed bank, such as bare rock, lava flows or recently exposed glacial till.
- Secondary succession
- Succession following a disturbance that leaves soil and seed banks intact, such as after fire, flood, logging or abandoned farmland.
- Pioneer species
- Early colonisers of bare substrate; typically fast-growing, widely dispersing and tolerant of harsh conditions, and they help build soil.
- Climax community
- The relatively stable late stage of succession whose composition reflects the regional climate and disturbance regime rather than continued directional change.
- Trophic level
- A feeding position in a food chain, such as producer, primary consumer or secondary consumer; energy decreases at each successive level.
- Ten percent rule
- The approximate proportion of energy transferred from one trophic level to the next; most energy is lost as heat and through respiration and excretion.
- Carrying capacity
- The maximum population size an environment can sustain given available resources, represented as K in the logistic growth equation.
- Density-dependent factor
- A limiting factor whose effect intensifies as population density rises, such as competition, disease or predation.
- Density-independent factor
- A limiting factor whose effect does not depend on population density, such as drought, fire, cyclones or volcanic eruption.
- Nitrogen fixation
- Conversion of atmospheric nitrogen gas into ammonia or related compounds by bacteria or industrial processes, making nitrogen available to organisms.
- Habitat fragmentation
- The breakup of continuous habitat into smaller, isolated patches, reducing gene flow and increasing extinction risk for small populations.
- Earth's four spheres
- The interacting atmosphere, hydrosphere, geosphere and biosphere; a change in one sphere typically produces responses in the others.
- Divergent plate boundary
- A boundary where tectonic plates move apart, creating new crust such as mid-ocean ridges and continental rift valleys, with shallow earthquakes and volcanism.
- Convergent plate boundary
- A boundary where plates move together; oceanic crust subducts, producing trenches, volcanic arcs, fold mountains and deep earthquakes.
- Transform plate boundary
- A boundary where plates slide past each other horizontally, generating strike-slip earthquakes with little or no volcanic activity.
- Rock cycle
- The set of processes converting rock among igneous, sedimentary and metamorphic types through melting, cooling, weathering, deposition and metamorphism.
- Law of superposition
- In undisturbed sedimentary sequences, each layer is older than the layers above it and younger than those below.
- Cross-cutting relationships
- A geological principle stating that a feature cutting across another, such as a fault or intrusion, is younger than the material it cuts.
- Half-life
- The time taken for half the radioactive parent atoms in a sample to decay; after n half-lives, one-half to the power n remains.
- Radiometric dating
- Determining absolute age from the ratio of radioactive parent to daughter isotopes, using a decay constant matched to the material's age.
- Climate proxy
- A preserved natural record, such as ice cores, tree rings, corals or sediments, used to infer past climate conditions before instrumental measurements.
- Greenhouse effect
- Atmospheric gases absorb and re-emit outgoing longwave radiation, warming the surface; the enhanced effect results from rising greenhouse gas concentrations.
- Albedo
- The proportion of incoming solar radiation reflected by a surface; ice and snow have high albedo, while oceans and forests have low albedo.
- Positive feedback
- A feedback loop that amplifies an initial change, such as reduced ice cover lowering albedo and increasing further warming.
- Negative feedback
- A feedback loop that counteracts an initial change, such as increased cloud cover reflecting more sunlight and moderating warming.
- Renewable resource
- A resource replenished by natural processes on human timescales, such as solar energy, wind, or forests managed within their regeneration rate.
- Ecological footprint
- An indicator of the land and water area required to supply a population's resources and absorb its wastes, expressed in global hectares.