A non-living, physical factor that influences an organism or ecosystem; ex: temperature, sunlight, pH, salinity, precipitation
Biochemical Oxygen Demand (BOD)
Measure of the amount of dissolved oxygen required to break down the organic material in a given volume of water through aerobic biological activity
Capable of being broken down by natural biological processes; ex: the activities of decomposer organisms
The amount of biological or living diversity per unit area. It includes species diversity, habitat diversity and genetic diversity.
Biomass/ Standing Crop
The mass of organic material in organisms or ecosystems. Sometimes "dry weight biomass" is used where mass is measured after the removal of water. Water is not organic material and inorganic material is usually relatively insignificant in terms of mass.
A collection of ecosystems sharing similar climatic conditions; ex: tundra, tropical rainforest, desert.
Part of the Earth inhabited by organisms, that is, the narrow zone in which plants and animals exist. It extends from the upper part of the atmosphere (where birds, insects and wind-blown pollen may be found) down to the deepest part of the Earth's crust to which living organisms live
A living, biological factor that influences an organism or ecosystem; ex: predation, parasitism, disease, competition.
Maximum number of species that can be sustainably supported by a given environment.
A community of organisms that is more or less stable, and that is in equilibrium with natural environmental conditions such as climate; the end point of ecological succession.
A group of populations living and interacting with each other in a common habitat.
A common demand by organisms upon limited supply of a resource; ex: food, water, light, space, mates, nesting sites. Intraspecific or interspecific.
Measure of the association between 2 variables. Move up or down, they positively correlated. Move in opposite directions, they are negatively correlated.
Crude Birth Rate
Number of births per thousand individuals in a population per year.
Crude Death Rate
Number of deaths per thousand individuals in a population per year.
A model describing the changing levels of fertility and mortality in a human population over time.
Term for heterogeneity. May refer to heterogeneity of species of habitat, or to genetic heterogeneity.
Range of genetic material present in a gene pool or population of a species.
Range of different habitats or numbers of ecological niches per unit area in an ecosystem, community or biome.
Numerical measure of species diversity that is derived from both the number of species (variety) and their proportional abundance.
Variety of species per unit area. Includes the number of species present and their abundance.
Number of years it would take a population to double its size at its current growth rate.
Area of land and water required to support a defined human population at a given standard of living. Takes into account the area required to provide all the resources needed for the population, and the assimilation of all wastes.
A community of interdependent organisms and the physical environment they inhabit.
A measure of the amount of disorder, chaos or randomness in a system; the greater the disorder, the higher the level of entropy.
Environmental Impact Assessment (EIA)
A method of detailed survey required, in many countries, before a major development. Includes a baseline study to measure environmental conditions before development happens, and to identify areas and species of conservation importance.
A state of balance among the components of a system.
The natural or artificial enrichment of a body of water, particularly with respect to nitrates and phosphates, that result in depletion of the oxygen content of the water. Eutrophication is accelerated by human activities that add detergents, sewage or agricultural fertilizers to bodies of water.
The cumulative, gradual change in the genetic characteristics of successive generations of a species or race of an organism, ultimately giving rise to species or races different from the common ancestor.
The return of part of the output from a system as input, so as to affect succeeding outputs.
Feedback that tends to damp down, neutralize or counteract from an equilibrium, and promotes stability.
Feedback that amplifies or increases change; away from an equilibrium.
In context of human populations, the potential for reproduction exhibited in a population. It may be measured as fertility rate, which is the number of births per thousand women of child- bearing age. Alternatively it may be measured as total fertility, which is simply the average number of children a women has in her lifetime.
Hypothesis developed by James Lovelock. It compares the Earth to a living organism in which feedback mechanisms maintain equilibrium.
An increase in average temperature of the Earth's atmosphere.
Gross National Production (GNP)
The current value if all goods and services produced in a country per year.
Those atmospheric gases which absorb infrared radiation, causing world temperatures to be warmer than they would otherwise be.
The environment in which a species normally lives.
Halogenated Organic Gases
Usually known as halocarbons and first indentified as depleting the ozone layer in the stratosphere. Now known to be greenhouse gases. The most well known are chlorofluorocarbons.
The process by which 2 populations become separated by. If gene flow between the 2 subpopulations is prevented, new species may evolve.
Species that concentrate their reproductive investment in a small number of offspring, thus increasing the survival rate and adapting them for living in long- term climax communities.
The angular distance from the equator (that is, north or south of it) as measured from the centre of the Earth (in degrees).
Less Economically Developed Country(LEDC)
A country with low to moderate industrialization and low to moderate GNP per capita.
More Economically Developed Country(MEDC)
A highly industrialized country with high average GNP per capita.
A simplified description designed to show the structure or workings of an object, system or concept.
A relationship between individuals of 2 or more species in which all benefit and none suffer. symbiosis relationship, ex: lichen and river she-oak tree.
A term sometimes used for natural resources that, if appropriately managed, can produce a "natural income" of goods and services.
Non- Renewable Natural Capital
Natural resources that cannot be replenished within a timescale of that same order as that at which they are taken from the environment and used; ex: fossil fuels.
Replenishable Natural Capital
Non-living natural resources that depend on the energy of the Sun for their replenishment; ex: groundwater.
A species share of a habitat and the resources in it. Depends on where the species lives and what it does.
A relationship between 2 species in which one species lives in or on another, gaining all or much of its food from it, symbiotic relationship. ex: a tick feeding on a dog
The movement of the 8 major and several minor internally rigid plates of the Earth's lithosphere in relation to each other and to the partially mobile asthenosphere below.
The addition to an environment of a substance or an agent by human activity, at a rate greater than that at which it can be rendered harmless by the environment, and which has an effect on the organism within it.
Non- Point Source Pollution
The release of pollutants from numerous, widely dispersed origins; ex: gases from exhaust systems in vehicles.
Point Source Pollution
The release of pollutants from a single, clearly identifiable site; ex: a factory chimney
A group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding.
Gross Productivity (GP)
The total gain in energy or biomass per unit area per unit time, which could be through photosynthesis in primary producers or absorption in consumers. GP= NP+R
Gross Primary Productivity (GPP)
The total gain in energy or biomass per unit area per unit time fixed by photosynthesis in green plants.GPP=NPP+R
Gross Secondary Productivity (GSP)
The total gain by consumers in energy or biomass per unit area per unit time through absorption. GSP= Food eaten- Faecal matter
Net Productivity (NP)
The gain in energy or biomass per unit area per unit time remaining after allowing for respiratory losses (R). NP= GP+R
Net Primary Productivity
The gain by producers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses (R). NPP= GPP - R
Net Secondary Productivity
The gain by consumers in energy or biomass per unit time remaining after allowing for respiratory losses (R). NSP= GSP-R
The gain by producers in energy or biomass per unit area per unit time.
The biomass gained by heterotrophic organisms, through feeding and absorption, measured in units of mass or energy per unit area per unit time.
Species that tend to spread their reproductive investment among a large number of offspring so that they are well adapted to colonize new habitats rapidly and make opportunistic use of short- lived resources.
The set of communities that succeed one another over the course of succession at a given location.
Haziness in the atmosphere caused by air pollutants.
An arbitrary group of individuals who share some common characteristics such as geographical location, cultural background, historical time frame, religious perspective, value system
A mixture of mineral particles and organic material that covers the land,
A vertical section through a soil , from the surface down to the parent material, revealing the soil layers of horizons.
The process through which new species form
A group of organisms that interbreed and produce fertile offspring.
The condition of a system in which there is a tendency for it to return to a previous equilibrium condition following disturbance.
Steady- State Equilibrium
The condition of an open system in which there are no changes over the longer term, but in which there may be oscillations in the very short term. There are continuing inputs and outputs of matter and energy, but the system as a whole remains in a more or less constant state.
The orderly process of change over time in a community. Changes in the community of organisms frequently cause changes in the physical environment that allow another community to become established and replace the former through competition.
Use of global resources at a rate that allows natural regeneration and minimizes damage to the environment.
An assemblage of parts and the relationship between them, which together constitute an entity or whole.
A system in which energy, but not matter, is exchanged with its surroundings.
A system that exchanges neither matter nor energy with its surroundings.
A system in which both matter and energy are exchanged with its surroundings.
The position that an organism occupies in a food chain, or a group of organisms in a community that occupy the same position in food chains.
The arrangement or patterning of plant communities or ecosystems into parallel or sub- parallel bands in response to change, over a distance, in some environmental factor.
(energy used for growth(new biomas)/ energy supplied x 100
the build-up of persistent/ non-biodegradable pollutants within an organism or trophic level because it cannot be broken down
the increase in concentration of persistent/ non-biodegradable pollutants along a food chain
pyramid of numbers
records the number of individuals at each trophic level coexisting in an ecosystem. Quantitative data for each trophic level are drawn to scale as horizontal bars arranged symmetrically around central axis
pyramid of biomass
represents the biological mass of the standing stock at each trophic level at a particular point in time measured in units such as grams of biomass per square meter
pyramid of productivity
shows the flow of energy through each trophic level of a food chain over a period of time. it is meausre in units of flow, joules
Carbon dioxide + water + sunlight -------> glucose + oxygen
Sunlight as energy source, carbon dioxide and water
glucose, used as energy source for the plant and as the starting material for other organic molecules, oxygen released into atmosphere through stomata
energy change is from light into stored chemical energy, and thus the chemical energy is stored in organic material(carbohydrates). Chlorophyll is necessary to capture certain visible wavelengths of sunlight and allows this energy to be transformed into chemical energy
glucose + oxygen ------> carbon dioxide + water
organic matter(glucose) and oxygen
release of energy for work and heat
oxidation process inside cells
energy transformation is from stored chemical energy into kinetic energy and heat. it is released in a for available for use by living organisms
also known as autotrophs, they convert abiotic components into living matter, they support the ecosystem by constant input of energy and new biological matter. ex: plants, bacteria, some algae
organisms that cannot maker their own food, eat other organisms to obtain energy and matter, also known as heterotophs which feed on producers(Autotrophs), carnivores feed on other heterotrophs and onmiovers feed on both
obtain their food and nutrients from the breakdown of dead organic matter. when they break down tissue, they release nutrients ready for re absorption by producers. and form the base of decomposer food chains. and contribute to build-up of hummus(organic material in soil made by decomposition of plant and animal matter.
s-population growth curve
when a graph of population growth for such species is plotted against time. It shows the intial rapid growth and then slows down as the carrying capacity is reached
first stage of an s-shaped population growth curve. population numbers are low leading to low birth rates. Because number are low, birth rates are also low
exponential growth phases
second stage of s-shaped population growth curve. population grows an rapidly.
third stage of s-shaped population growth curve. population growth slows down considerably although continuing to grow. limiting factors, competition for resources, predators, disease, mortality
fourth and final stage of s-shaped population growth curve. population size stabilizes and pop. fluctuates around level that represents carrying capacity. limiting factors, predation, disease and abiotic factors
lower the birth rate or raise the death rate as a population grows
those which affect a pop. irrespecitve of population density.
competition within a species
competition between species.
law of tolerance
states that "For each abiotic factor, an organism has a range of tolerances within which it can survive."
full range of conditions and resources in which a species could survive and reproduce
actual conditions and resources in which a species exists due to biotic factors
electronic thermometer with probes allows this to be accurately measured in air, water,
measure using a pH meter or data logging probe values range with 7 being alkaline 0 acidic
measure using the beaufort scale. precise measures can be done with digital anemometer, can be mounted or hand held.
surface run-off is determined by this.
can be measured using electrical conductivity. or by the density of the water. often expressed as Parts Per Thousands(PPT)
cloudy water is said to have high turbidity. it affects the penetration of sunlight into water and therefore rates of photosynthesis.
first law of thermodynamics
energy can neither be created nor destroyed; it can only change form
second law of thermodynamics
energy goes from a concentrated form(sun) into dispersed forms(heat)
when a small change can have potentially drastic effects.
positive feedback loop
an increase in temperature from increased greenhouse emissions and fossil fuels (climate change- global warming)
Negative feedback loop
Often it causes the output of a system to be lessened; so, the feedback tends to stabilize the system
EIA(Environmental Impact assesment
the process of evaluation and identifying potentially environmental impacts following a project,
Point source pollution
Refers to discrete sources of contamination that can be represented by single points on a map eg Chernobyl and Fukushima
Non point source pollution
Refers to more dispersed sources from which pollutants originate and enter the natural environment e g cars or industries
Active or emissions such as gas released from burning coal
Arising from primary pollutant undergoing physical change or chemical change such as car exhausts
Acute effects of pollution
Occurring after short period of time like asthma attacks
Chronic effects of pollution
Occurring after low level long term exposure e g air pollution
Those that cannot be broken down by living organisms and so passed along a good change DDT
Persistent organic pollutants
Organic compounds that are resistant to environmental breakdown
Those that are not stored in biological matter passed along food chains
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IB Environmental Systems and Societies Definitions