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Ecosystem

A community of living things and their physical environment interacting together.

Open system

A system that exchanges both energy and matter with its surroundings.

Closed system

A system that exchanges energy but not matter with its surroundings.

Producer

An organism (like a plant) that makes its own food, usually by photosynthesis.

Consumer

An organism that eats other organisms for energy.

Apex predator

A predator at the top of the food chain with no natural enemies.

Food chain

A sequence showing who eats whom in an ecosystem.

Food web

A network of connected food chains showing how energy flows in an ecosystem.

Decomposer

An organism (like fungi or bacteria) that breaks down dead organisms.

Detritivore

An organism that feeds on dead organic matter (like earthworms).

Saprotroph

An organism that digests dead material outside its body and absorbs nutrients (e.g. fungi).

Autotroph

An organism that makes its own food using energy from light or chemicals.

Photoautotroph

An autotroph that uses sunlight to make food (like plants).

Chemoautotroph

An autotroph that uses chemical energy (not sunlight) to make food.

Carbon fixation

The process of turning carbon dioxide into organic compounds (like glucose).

Heterotroph

An organism that gets its food by eating other organisms.

Digestion

Breaking down food into smaller molecules the body can use.

Assimilation

The process of absorbing nutrients into cells after digestion.

Synthesis

The creation of complex molecules from simpler ones.

Cellular respiration

A process where cells release energy by breaking down glucose.

Oxidation

A chemical reaction where a substance loses electrons, often releasing energy.

Trophic level

A position in a food chain or web (like producer, primary consumer, etc.).

Pyramid of energy

A diagram showing how much energy is available at each trophic level.

Biomass

The total mass of living material in a given area.

Gross primary production (GPP)

The total amount of energy made by producers.

Net primary production (NPP)

The energy left for consumers after producers use some for themselves.

Secondary production

The creation of new biomass by consumers.

Sink

A place where something (like carbon) is stored.

Pool

A store or reservoir of matter (e.g. carbon in the atmosphere or biomass).

Flux

The movement of matter (like carbon) between pools.

Carbon sink

A natural store that absorbs more carbon than it releases (e.g. forests).

Carbon source

A process or area that releases carbon into the atmosphere.

Sequestration

The process of storing carbon in a stable form (e.g. in trees or soil).

Combustion

Burning something, usually releasing carbon dioxide.

Keeling Curve

A graph showing rising carbon dioxide levels in the atmosphere over time.

Diffusion

The movement of molecules from high to low concentration.

Photosynthesis

The process where plants use sunlight to make food (glucose) from CO₂ and water.

Respiration

The process of breaking down food to release energy.

Nutrient cycling

The movement and reuse of nutrients through an ecosystem.

Natural selection

The process where organisms better suited to their environment survive and reproduce more successfully.

Evolution

The gradual change in a species over time through changes in inherited traits.

Inductive reasoning

Making general conclusions based on specific observations or patterns.

Correspondence theory of truth

The idea that something is true if it matches reality.

Coherence theory of truth

The idea that something is true if it fits logically with other known truths.

Pragmatic theory of truth

The idea that something is true if it works or has practical results.

Mutation

A change in DNA that can lead to new traits in organisms.

Genetic variation

Differences in DNA among individuals in a population.

Meiosis

A type of cell division that makes gametes (sex cells) with half the usual number of chromosomes.

Sexual reproduction

Reproduction involving two parents, combining their genetic material to create offspring.

Overproduction

When organisms produce more offspring than the environment can support.

Carrying capacity

The maximum number of individuals an environment can support.

Direct competition

When organisms fight over the same resource.

Indirect competition

When organisms use the same resource without direct conflict.

Selective pressure

Environmental factors that affect an organism's ability to survive and reproduce.

Density-independent factor

A factor that affects a population regardless of its size (e.g. weather, natural disasters).

Adaptation

A trait that helps an organism survive and reproduce in its environment.

Fitness

How well an organism survives and reproduces in its environment.

Heritable characteristic

A trait that can be passed from parents to offspring through genes.

Acquired characteristic

A trait gained during an organism's life (not inherited genetically).

Sexual selection

A type of natural selection based on traits that attract mates.

Courtship behavior

Behaviors animals use to attract mates (e.g. dances, sounds, displays).

Model (scientific)

A simplified representation of a system or process to help understand or predict how it works.

Stability (ecosystem)

When an ecosystem stays balanced over time, despite small changes.

Tipping point

A critical point where a small change causes a big, often irreversible, shift in the ecosystem.

Mesocosm

A controlled, small-scale ecosystem used for experiments.

Keystone species

A species that has a big impact on its ecosystem; removing it can cause major changes.

Sustainability

Using resources in a way that meets current needs without harming future generations.

Resource harvesting

Taking natural resources (like fish, trees, or crops) from the environment for human use.

Maximum sustainable yield

The largest amount of a resource that can be used without depleting it.

Eutrophication

Too many nutrients (like from fertilizers) in water, leading to algae growth and oxygen loss.

Biomagnification

The build-up of harmful substances in animals higher up the food chain.

Mercury

A toxic heavy metal that can build up in organisms and cause health problems.

DDT

A harmful pesticide that accumulates in animals and caused problems like thin bird eggshells.

Biodegradable

Able to break down naturally by bacteria or other living things.

Microplastic

Tiny plastic pieces (less than 5 mm) that pollute the environment.

Macroplastic

Larger plastic items like bottles or bags that can harm wildlife and ecosystems.

Rewilding

Restoring nature by letting ecosystems return to a natural, wild state (often by reintroducing species).

Greenhouse effect

When greenhouse gases trap heat in Earth's atmosphere, keeping the planet warm.

Enhanced greenhouse effect

Extra warming caused by more greenhouse gases from human activities.

Anthropogenic

Caused by humans (e.g. pollution or climate change).

Methane

A strong greenhouse gas released by cows, landfills, and melting permafrost.

Carbon dioxide (CO₂)

A greenhouse gas released by burning fossil fuels and respiration.

Positive feedback

A change that causes even more change in the same direction (e.g., warming melts ice, which causes more warming).

Boreal forest

Cold, northern forests made mostly of pine and spruce trees.

Landfast ice

Sea ice that is attached to the land and doesn't float away.

Sea ice

Frozen ocean water that floats on the sea surface.

Upwelling

When deep, cold, nutrient-rich water rises to the surface.

Ocean stratification

Layers of ocean water that don't mix well due to differences in temperature or salinity.

Ocean current

Large-scale movement of ocean water, like the Gulf Stream.

Primary production

The amount of energy made by plants and algae using sunlight.

Poleward shift

When species move closer to the poles because of warming temperatures.

Upslope shift

When species move to higher elevations to stay in their preferred temperature.

Coral reef

Underwater ecosystems made by coral that support lots of marine life.

Ocean acidification

When CO₂ dissolves in the ocean, making it more acidic and harming marine life.

Carbon sequestration

Capturing and storing CO₂ from the atmosphere.

Afforestation

Planting trees in areas that didn't have forests before.

Reforestation

Replanting trees in areas where forests were cut down.

Peatland restoration

Repairing peatlands (wetlands with lots of stored carbon) to reduce CO₂ emissions.