AP Environmental Science Unit 1 - Ecosystems

Vocabulary practice flashcards covering Unit 1: Ecosystems, Biomes, Biogeochemical Cycles, and Trophic Dynamics.

Population

A group of individuals belonging to the same species living in a given area.

Community

All of the living organisms interacting within a given area.

Ecosystem

A community of organisms together with all the biotic and abiotic factors in their environment.

Biome

A large ecological region characterized by a similar climate, which determines the specific plant and animal organisms that can thrive there.

Ecological Levels of Organization

The hierarchical arrangement of ecological study ranging from an individual organism to population, community, ecosystem, biome, and biosphere.

Symbiosis

A close, long-term interaction between two organisms of different species in an ecosystem.

Mutualism

A symbiotic interaction in which both species benefit from the relationship (e.g., coral providing habitat to zooxanthellae in exchange for photosynthetic sugars).

Commensalism

A symbiotic relationship in which one organism benefits while the other is unaffected (e.g., remora fish attached to a stingray).

Parasitism

A symbiotic interaction where one organism benefits at the expense of another host organism.

Parasitoid

An organism that lays eggs inside a host; the hatched larvae then prey on the host's tissue for energy, ultimately killing it.

Ecological Niche

The specific area occupied by an organism within its habitat, along with its functional role and interactions within its ecological community.

Limiting Factor

Any abiotic or biotic factor that restricts or prevents the growth, abundance, or distribution of a population in an ecosystem.

Predator-Prey Cycle

A recurring dynamic in which rapid growth of a prey population causes predator numbers to increase, leading to increased predation that reduces the prey population, subsequently causing predator numbers to decline.

Interspecific Competition

Competition for limited resources occurring between individuals of different species.

Intraspecific Competition

Competition for limited resources occurring between individuals of the same species.

Resource Partitioning

The strategy where competing species divide or utilize resources in different ways, places, or times to reduce competition and co-exist.

Temporal Partitioning

A form of resource partitioning where competing species utilize the same resource at different times of the day or night.

Spatial Partitioning

A form of resource partitioning where competing species use different physical areas or locations within a shared habitat.

Morphological Partitioning

A form of resource partitioning where competing species evolve different physical body structures to utilize different resources.

Biome Distribution

The global pattern of terrestrial biomes, determined primarily by average annual temperature and precipitation, which vary according to latitude and distance from the equator.

Taiga (Boreal Forest)

A high-latitude ($50\text{--}60^\text{o}\text{N}$) forest biome dominated by evergreen coniferous trees, characterized by an average temperature around $32^\text{o}\text{F}$ ($0^\text{o}\text{C}$), slow needle decomposition, and nutrient-poor soil.

Tundra

A high-latitude ($60\text{--}75^\text{o}\text{N/S}$) cold biome with temperatures ranging from $-30\text{--}20^\text{o}\text{F}$, low precipitation ($150\text{--}250\text{ mm}$), sparse vegetation, and a permanent subsoil layer called permafrost.

Temperate Rainforest

A coastal mid-latitude ($40\text{--}60^\text{o}\text{N/S}$) biome featuring large coniferous trees, ferns, mosses, moderate temperatures ($68\text{--}77^\text{o}\text{F}$), and nutrient-poor soil due to slow decomposition.

Temperate Seasonal Forest

A mid-latitude ($25\text{--}50^\text{o}\text{N/S}$) biome dominated by broadleaf deciduous trees, characterized by an average temperature of $50^\text{o}\text{F}$, rapid decomposition, and fertile soil.

Shrubland

A biome found at $30\text{--}40^\text{o}\text{N/S}$ latitude with temperatures ranging $-1\text{--}38^\text{o}\text{C}$, characterized by drought- and fire-adapted vegetation and nutrient-poor soil from leaching.

Temperate Grassland

A mid-latitude ($23.5^\text{o}\text{N/S}$) biome with high plant productivity, fertile soil from rapid decomposition, frequent natural fires, and vegetation dependent on seasonal rainfall.

Tropical Rainforest

A warm, wet equatorial biome ($20^\text{o}\text{N/S}$) with high productivity, distinctive canopy layers, low soil nutrients due to rapid plant uptake, and high biodiversity harboring 2/3 of terrestrial species.

Savanna

A tropical seasonal forest biome characterized by warm temperatures, distinct wet and dry seasons, open grasslands with scattered trees, and natural grazing and fires that inhibit woody plant growth.

Subtropical Desert

A biome located near $30^\text{o}\text{N/S}$ latitude characterized by hot temperatures, extremely low rainfall, and drought-adapted succulent plants like cacti with thick exteriors and spines.

Oligotrophic Lake

A deep, cold, nutrient-poor young lake characterized by clear water, low phytoplankton productivity, and minimal organic matter in its benthos.

Mesotrophic Lake

A middle-aged lake characterized by moderate nutrient content, moderate levels of phytoplankton, and medium biological productivity.

Eutrophic Lake

A shallow, warm, nutrient-rich old lake with high phytoplankton productivity, murky water, and elevated decomposition rates in its benthos that can deplete oxygen levels.

Littoral Zone

The shallow, near-shore area of a freshwater lake where light reaches the bottom and allows rooted emergent plants to grow.

Limnetic Zone

The open, well-lit surface region of a lake away from shore where photosynthesis occurs, dominated by floating phytoplankton rather than rooted plants.

Profundal Zone

The deep, dark zone of a freshwater lake located beneath the limnetic zone where sunlight cannot penetrate, preventing photosynthesis.

Benthic Zone

The muddy bottom sediment layer of an aquatic ecosystem inhabited by decomposers and invertebrate organisms.

Wetland

An ecosystem with soil that is submerged or saturated with water for at least part of the year, shallow enough to support emergent vegetation like cattails and reeds.

Photic Zone

The upper layer of ocean water that receives sufficient sunlight for photosynthesis to take place.

Aphotic Zone

The deeper layer of the ocean (abyssal region) that receives no sunlight, preventing photosynthetic growth.

Coral Bleaching

The death or expulsion of symbiotic photosynthetic algae within corals due to stressors like ocean acidification or rising temperatures, causing the coral to turn white and die.

Estuary

A highly productive coastal wetland area where freshwater rivers mix with saltwater from the ocean.

Salt Marsh

A temperate coastal estuary habitat dominated by non-woody emergent plants that serves as a crucial breeding ground for marine fish and shellfish.

Mangrove Swamp

A tropical coastal wetland biome dominated by mangrove trees with dense stilt roots that prevent shoreline erosion and buffer against storm surges.

Intertidal Zone

The narrow strip of coastline between the high tide and low tide marks, exposing organisms to crashing waves and desiccation during low tide.

Carbon Sink

A natural or artificial reservoir that absorbs and stores more carbon than it releases into the atmosphere (e.g., ocean sediments, living forests, soil).

Carbon Source

A process or reservoir that releases more carbon into the atmosphere than it absorbs (e.g., fossil fuel combustion, deforestation, animal agriculture).

Carbon Cycle

The biogeochemical cycle tracking the movement of carbon molecules between atmospheric, terrestrial, oceanic, and geological reservoirs via processes like photosynthesis, respiration, burial, and combustion.

Sedimentation

The process in the carbon cycle where organic matter and mineral particles sink to the ocean floor and accumulate into carbon-containing sedimentary layers.

Burial

The long-term geological process where accumulated organic sediments are subjected to pressure and heat, converting them into fossil fuels or sedimentary rocks like limestone.

Nitrogen Fixation

The process converting inert atmospheric nitrogen gas ($\text{N}_2$) into biologically available forms such as ammonia ($\text{NH}_3$) or ammonium ($\text{NH}_4^+$), primarily carried out by specialized soil and root bacteria.

Assimilation

The process by which plants absorb inorganic nitrogen compounds ($\text{NO}_3^-$ or $\text{NH}_3$) from soil and incorporate them into biological tissues like amino acids and nucleic acids.

Ammonification

The breakdown of nitrogenous organic waste and dead tissue by decomposers, converting it back into ammonium ($\text{NH}_4^+$) in the soil.

Nitrification

A two-step biological process where soil bacteria convert ammonium ($\text{NH}_4^+$) first into nitrite ($\text{NO}_2^-$) and then into nitrate ($\text{NO}_3^-$).

Denitrification

The bacterial process of reducing nitrates ($\text{NO}_3^-$) in anaerobic soil conditions back into gaseous nitrous oxide ($\text{N}_2\text{O}$) and atmospheric nitrogen gas ($\text{N}_2$).

Eutrophication

An ecological process where excess nutrient runoff (nitrogen or phosphorus) causes a rapid bloom of algae, blocking sunlight and subsequently causing hypoxic conditions as decomposers consume dissolved oxygen during algal decay.

Phosphorus Cycle

A slow sedimentary cycle moving phosphorus through rocks, soil, water, and living organisms without any significant atmospheric gas phase.

Geological Uplift

Tectonic plate movements that lift ocean sediment rock layers up onto land, exposing phosphorus-bearing rocks to wind and rain weathering.

Transpiration

The movement of groundwater up through plant roots and stems to leaves, where it evaporates into the atmosphere through microscopic leaf pores called stomata.

Evapotranspiration

The combined total water vapor entering the atmosphere from soil and open water evaporation plus plant transpiration.

Infiltration

The process by which liquid water on the ground surface soaks and trickles down into soil layers and groundwater aquifers.

Runoff

Precipitation that travels across the land surface into lakes, rivers, and streams instead of soaking into soil or evaporating.

Hydrologic Cycle

The solar-powered movement of water in solid, liquid, and gaseous states between ocean, atmospheric, terrestrial, and groundwater reservoirs.

Water Distribution

The breakdown of Earth's water supply, consisting of approximately 97\text{\null}\% saline ocean water and 3\text{\null}\% freshwater (the majority of which is locked in glaciers and ice caps).

Primary Productivity

The rate at which solar energy is converted into organic compounds by producers through photosynthesis over a specific unit of time.

Gross Primary Productivity (GPP)

The total rate of energy capture via photosynthesis in a given area over a specific time period.

Net Primary Productivity (NPP)

The rate of energy storage by producers after accounting for energy lost through cellular respiration: $\text{NPP} = \text{GPP} - R$.

10% Rule

The ecological principle stating that only about 10\text{\null}\% of usable chemical energy is successfully passed from one trophic level up to the next higher level in a food chain.

Food Web

A complex network model of interconnected food chains depicting the multidirectional flow of energy and nutrients among organisms across various trophic levels.