AP Environmental Science: Ecosystem Ecology, Biogeochemical Cycles, and Biomes

Vocabulary practice flashcards covering AP Environmental Science concepts including the nitrogen, hydrologic, carbon, and phosphorus cycles, terrestrial and aquatic biomes, and trophic energy dynamics.

Nitrogen Fixation

The process illustrated in the nitrogen cycle where atmospheric nitrogen gas ($N_2$) is converted into usable chemical forms (such as ammonia, $NH_3$) available to producers, often facilitated by specialized bacteria.

Nitrification

The biological process performed by soil bacteria involving the conversion of ammonium ions ($NH_4^+$) into nitrite ions ($NO_2^-$), and subsequently into nitrate ions ($NO_3^-$).

Denitrification

The reduction of soil nitrates ($NO_3^-$) back into nitrogen gas ($N_2$) by specialized bacteria, releasing nitrogen back into the atmosphere.

Atmosphere (in the Nitrogen Cycle)

The largest reservoir of nitrogen on Earth, composed of approximately $80\%$ free nitrogen gas ($N_2$) and containing roughly $3,870,000,000\text{ tetragrams}$ of nitrogen.

Food Web Arrows

Visual vectors in an ecological diagram that indicate the directional flow of energy between trophic levels as one organism feeds on another.

10% Rule of Energy Transfer

An ecological principle based on thermodynamics stating that approximately $90\%$ of available energy is lost between trophic levels, and only about $10\%$ is transferred and stored in the next trophic level.

Generalist Species

Organisms that feed on a broad variety of food resources and can thrive under diverse environmental conditions, such as both the native white-tailed deer and nonnative sika deer.

Mutualism

A symbiotic ecological relationship in which both interacting species benefit, such as reef corals providing shelter while resident microalgae supply vital nutrients.

Resource Partitioning

The division of environmental resources by coexisting species to minimize niche overlap and competition, exemplified by two distinct bird species feeding from different parts of the same oak tree (one eating acorns, the other eating bark insects).

Tropical Rain Forest

A terrestrial biome with the highest primary productivity and net primary productivity per unit area, supported by a yearlong growing season, warm temperatures, and over $60\text{ inches}$ of rainfall annually.

The Sun (in the Hydrologic Cycle)

The foundational external energy source that powers the global movement of water, driving evaporation and atmospheric circulation.

Freshwater Wetlands

An aquatic biome rich in nutrients from falling leaves and trapped organic debris from large trees, which provides the critical ecosystem service of filtering pollutants from water.

Coral Reefs

A marine biome found in warm, shallow coastal waters that represents Earth's most biologically diverse marine ecosystem.

Rivers

A freshwater biome characterized by fast-flowing, turbulent water originating from springs or surface runoff, which carries sediments, organic matter, and forms rapids.

Carbon Source

Any ecological or industrial process, such as the combustion of fossil fuels, that releases more carbon dioxide and carbon compounds into the atmosphere than it absorbs.

Carbon Sink

A natural reservoir that absorbs and stores carbon compounds; includes long-term geological reservoirs like sedimentary limestone ($CaCO_3$) and short-term biological reservoirs like vegetation.

Phosphorus Cycle

A sedimentary biogeochemical cycle driven by rock weathering and geological uplift that notably lacks a significant gaseous or atmospheric component.

Sedimentary Rock (in the Phosphorus Cycle)

The largest reservoir of phosphorus on Earth, where phosphate ions remain stored until released by physical weathering and erosion.

No-Till Agriculture

A soil conservation practice that reduces erosion from farmland, keeping phosphorus within agricultural soil, reducing fertilizer needs, and preventing excessive algal blooms in nearby coastal waters.

Gross Primary Productivity (GPP)

The total rate of solar energy converted into chemical energy via photosynthesis by autotrophs in a given area over a given period of time.

Net Primary Productivity (NPP)

The rate at which energy is stored as biomass by producers after subtracting the energy consumed by the producers for cellular respiration ($\text{NPP} = \text{GPP} - R$), representing the energy available to consumers.

Cellular Respiration

The metabolic breakdown of organic compounds (sugars) to yield cellular energy ($\text{ATP}$), a reaction measurable in the dark by calculating the volume of oxygen gas ($O_2$) consumed over time.

Phytoplankton

Microscopic, photosynthesizing aquatic autotrophs that serve as the primary producers at the base of marine pelagic food chains.

Primary Producer

An autotrophic organism that uses solar energy to synthesize organic molecules (sugars) from water and carbon dioxide, serving as the first trophic level in a food chain.