IB Environmental Systems and Societies (IB ESS) Exam Review

Practice vocabulary flashcards for IB ESS Quarter 1 review covering systems, thermodynamics, ecological interactions, aquatic biomes, and environmental value systems.

Global Water Cycle Storages

The major storage reservoirs of water on Earth expressed as percentages of total water: Oceans ($97\%$), Ice ($2\%$), Ground Water ($1\%$), Surface Water ($0.001\%$), Atmospheric Water Vapour ($0.001\%$), and Clouds ($0.001\%$).

Sustainable Yield (SY)

The amount of a natural resource (such as fish) that can be extracted without depleting the base stock, calculated as: $\text{SY} = (\text{annual growth \& recruitment}) - (\text{annual death \& emigration})$ or $\text{SY} = (\text{inputs/fish added}) - (\text{outputs/fish caught})$.

Recruitment

The addition of new individuals to a population through natural reproduction.

Simpson's Diversity Index

A mathematical measure of species richness and relative abundance calculated with the formula: $D = \frac{N(N-1)}{\sum n(n-1)}$, where $D$ is the diversity index, $N$ is the total number of organisms of all species found, and $n$ is the number of individuals of each particular species.

Top Carnivores

Keystone species, such as polar bears and wolves, that exist at the ultimate end of the flow of energy in a food chain or food web.

Species

A group of organisms that can interbreed and produce fertile offspring.

Population

A group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding.

Herbivores

Primary consumers that eat only plants.

Carnivores

Animals that consume meat.

Community

A group of populations living and interacting with each other in a common habitat.

Ecosystem

A community of interdependent organisms and the physical environment they inhabit, such as a salt marsh.

Competition

A common demand by two or more organisms upon a limited supply of a resource (such as food, water, light, space, mates, or nesting sites), which may be intraspecific or interspecific.

Predation

The feeding strategy typical of secondary and tertiary consumers in which one animal captures and consumes another.

Herbivory

The feeding strategy typical of primary consumers that feed on autotrophic producers.

Producers

Autotrophs that synthesize organic food molecules from inorganic molecules using an external energy source such as the sun.

Consumers

Heterotrophs that obtain energy and nutrients by feeding on other organisms; they can be classified as primary, secondary, tertiary, or quaternary.

Decomposers

Fungi and bacteria that break down complex organic material into simpler molecules, recycling matter within an ecosystem but not energy.

Abiotic Factor

A non-living, physical factor that may influence an organism or ecosystem; examples include temperature, sunlight, pH, salinity, precipitation, and dissolved oxygen.

Biotic Factor

A living biological factor that may influence an organism or ecosystem; examples include predation, parasitism, disease, competition, and Biochemical Oxygen Demand (B.O.D.).

Trophic Level

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.

Food Chain

A linked feeding series in which a sequence of organisms transfer materials and energy.

Food Web

A complex interlocking series of individual food chains.

Biomass

The mass of organic material in organisms or ecosystems, usually measured per unit area (often expressed as dry weight after the removal of water).

Pyramid of Numbers

A graphical model of the number of individual organisms present at each trophic level of an ecosystem, representing a storage within the system.

Pyramid of Biomass

A graphical model that represents the standing stock/storage of each trophic level, measured in units of mass per unit area such as $\text{g}\,\text{m}^{-2}$ or units of energy such as $\text{J}\,\text{m}^{-2}$.

Pyramid of Productivity

A graphical model that represents the flow of energy through each trophic level over time, usually measured in units of flow such as $\text{g}\,\text{m}^{-2}\,\text{yr}^{-1}$ or $\text{J}\,\text{m}^{-2}\,\text{yr}^{-1}$.

Ecological Pyramid

A graphical model displaying quantitative differences between trophic levels that follows the second law of thermodynamics, narrowing as one ascends because energy and biomass decrease along food chains.

Mangrove-Coral Reef Interdependence

An ecological relationship where mangrove roots and sea grass trap sediments and chemicals to maintain clear water for coral reefs and serve as nurseries for young organisms, while adult shrimps, lobsters, and fish migrate outward to inhabit the main coral reef.

10% Rule

An ecological principle stating that approximately $10\%$ of energy is transferred to each successive trophic level, whereas approximately $90\%$ is lost as metabolic heat or unconsumed material.

Transfer

A system process that involves a change in location or movement of matter or energy without a change in chemical state, form, or molecular properties (e.g., surface run-off or groundwater flow).

Transformation

A system process that involves a change in state of matter, chemical composition, or energy type (e.g., evaporation of liquid water into atmospheric water vapour or condensation into clouds).

Flows vs. Storages

In systems terminology, storages (stocks) represent quantities of energy or matter accumulated within a system, whereas flows represent inputs and outputs moving into, through, or out of the system.

System

A set of connected things, parts, or devices that operate together, characterized by inputs, outputs, feedbacks, and internal components.

Open System

A system that exchanges both matter and energy with its surroundings (e.g., natural ecosystems).

Closed System

A system that exchanges energy with its surroundings but does not exchange matter (e.g., planet Earth as a whole).

Isolated System

A theoretical system that exchanges neither matter nor energy with its surroundings.

Steady-State Equilibrium

An equilibrium characteristic of open systems where continuous inputs and outputs of energy and matter occur, causing small fluctuations around a mean while the system as a whole maintains a constant state.

Static Equilibrium

A state where there are no inputs or outputs of matter or energy and no change in the components over time (characteristic of non-living, mechanical systems).

Negative Feedback

A self-regulating mechanism in which the system's output counteracts deviations from an equilibrium set-point, driving the system back toward stability.

Positive Feedback

A destabilizing mechanism in which a change in a system leads to further amplification of that change, driving the system away from its original equilibrium.

Lag Time

The interval or time delay that occurs between an initial stimulus or input into a system and the system's corresponding feedback response.

Ecocentric

An environmental value system (EVS) that prioritizes the bio-rights of all living things, emphasizes the intrinsic value of nature, and encourages individual restraint and holistic ecological balance.

Anthropocentric

A human-centered environmental value system (EVS) that views nature as a resource for human benefit, managing ecosystems through human governance, regulations, and economic instruments.

Technocentric

An environmental value system (EVS) that emphasizes technology, science, and human ingenuity as the primary solutions to environmental degradation and resource depletion.