Ultimate Guide: AP Environmental Science

Ecosystem

A community of living (biotic) organisms interacting with the non-living (abiotic) components of their environment as a system through various nutrients and energy cycles.

Organism

A living thing that can function on its own.

Species

Organisms that resemble each other; are similar in genetic makeup, chemistry, and behavior; and are able to interbreed and produce fertile offspring.

Interspecific

occurring between different species.

Population

Organisms of the same species that interact with each other and occupy a specific area.

Community

Population of different species.

Ecological Niche

A particular area within a habitat occupied by an organism, as well as the function of that organism within its ecological community.

Physical Environment

non-living aspects of our surroundings that affect living organisms and ecosystems

Niche

Unique adaptations, position and role of an organism within an ecosystem

Symbiosis

any type of close and long-term biological interaction between two different biological organisms of the same or different species

Amensalism

The interaction between two species whereby one species suffers and the other species is not affected.

Commensalism

The interaction between two species whereby one organism benefits and the other species is not affected.

Competition

Interaction between organisms when they share limited resources in an ecosystem

Intraspecific

Competition between members of the same species.

Interspecific

Competition between members of different species.

Predator–Prey Relationships

Interaction between two species where one hunts and consumes the other for food and where most competition takes place

Mutualism

The interaction between two species whereby both species benefit.

Parasitism

The interaction between two species whereby one species is benefited, and the other species is harmed.

Opportunistic Predators

Organisms that adapt their diet based on the availability and ease of capture of their prey

Specialist predators

organisms that are highly adept at hunting and consuming a specific prey species, or even just a specific life stage of that species.

Saprottrophism

Organisms that obtain their nutrients from dead or decaying plants or animals through the absorption of soluble organic compounds.

Law of Tolerance

the existence, abundance, and distribution of species depend on the tolerance level of each species to both physical and chemical factors.

Limiting Factor

Any abiotic factor that limits or prevents the growth of a population.

Predator-prey cycles

Based on a feeding relationship between two species

Morphological Partitioning

When two species share the same resource but have evolved slightly different structures to utilize the same resource

Spatial Partitioning

When competing species use the same resource by occupying different areas or habitats within the range of occurrence of the resource

Temporal Partitioning

When two species eliminate direct competition by utilizing the same resource at different times

Biomes

Major regional or global biotic communities characterized by dominant forms of plant life and the prevailing climates

Deserts

A region characterized by extremely low precipitation

Arctic tundra

characterized by extremely cold temperatures, short growing seasons, permafrost, and treeless plains

Succulents

Plants that have fleshy leaves or stems that store water.

Cactus

Plants that secrete toxins into the soil to prevent interspecific competition and have sharp spines that create shade, reduce drying airflow, discourage herbivores, and reflect sunlight.

Wildflowers

Plants that depend on water for germination, have short life spans, and perform their entire life cycle from seed to flower to seed within a single growing season

Desert Animals

Species that are generally small (small surface area), often nocturnal, and spend most of their time in undergrown burrows when cold

Aestivation

summer hibernation

Forests

Covers about one-third of Earth's land surface and accounts for 75% of gross primary productivity and plant biomass.

Closed canopy

When tree crowns cover more than 20% of the ground’s surface, forming a thick layer that blocks sunlight from reaching the ground

Open canopy

When tree crowns cover less than 20% of the ground surface, allowing more sunlight to reach the ground

Tropical Rainforests

Lush, evergreen forests found in warm, humid regions near the equator, characterized by tall trees, abundant rainfall, and incredible biodiversity.

Overstory

The uppermost trees in a forest.

Understory

Layer made up of young trees, short species of trees, shrubs, and soft-stemmed plants.

Temperate Deciduous Forests

Vibrant ecosystems found in mid-latitude regions around the world, and characterized by distinct seasonal changes, with green foliage in spring and summer and display of colors and leaf loss in autumn.

Temperate Coniferous Forest

vast, evergreen ecosystems found in the cooler regions of the Northern Hemisphere, and characterized by tall, cone-bearing trees that remain green throughout the year, even during harsh winters. also known as southern taiga/boreal forests

Taiga

Largest terrestrial biome; found in northern Eurasia, North America, Scandinavia, and two-thirds of Siberia.

Southern Taiga (Boreal Forest)

Consists primarily of cold-tolerant evergreen conifers with needle-like leaves, such as pines, spruces, and larches.

Northern Taiga

Environment that gets more barren as it approaches the tree line and the tundra biome.

Grasslands

Lands dominated by grasses rather than by large shrubs or trees.

Savannas

Grasslands with scattered individual trees and cover almost half the surface of Africa and large areas of Australia, South America, and India.

Temperate Grasslands

Environment where grasses are the dominant vegetation, while trees and large shrubs are absent.

Tundra

Environment that has extremely low temperatures, low biotic diversity, and simple vegetation structure.

Arctic tundra

A treeless biome found in the far northern regions of the Earth, primarily encircling the Arctic Ocean characterized by extremely cold temperatures, short growing seasons, permafrost (permanently frozen ground), and sparse vegetation.

Permafrost

Layer of permanently frozen subsoil.

Alpine tundra

A treeless biome found at high elevations above the treeline, typically on mountain ranges around the world

Antarctica

Continent with the coldest climate on Earth.

Ice Sheet

Formed from compressed snow that rarely melts.

Krill

Key food source in arctic ecosystems and serves as food for many predators.

Convection

The circular motion that occurs when warmer air or liquid rises, while the cooler air or liquid sinks.

Thermohaline currents

Drive a conveyor belt of ocean water that moves constantly, unlike most surface currents, which are driven by winds.

Littoral Zone ( intertidal zone)

Part of the ocean that is closest to the shore.

Neretic Zone

Also known as the sublittoral zone , this zone extends to the edge of the continental shelf.

Photic Zone

The uppermost layer of water in a lake or ocean that is exposed to sunlight down to the depth where 1% of surface sunlight is available.

Photic Zone

The layer just above the depth where the rate of carbon dioxide uptake by plants is equal to the rate of carbon dioxide production by animals.

Corals

Marine invertebrates that typically live in compact colonies of many identical individual polyps.

Polyps

Small, sac-like animals with a set of tentacles surrounding a central mouth opening and an exoskeleton made of calcium carbonate at the base.

Zooxanthellae

Single-celled dinoflagellates that live in a symbiotic relationship with most reef-building corals

Fringing reefs

Most common reef type that grows near the coastline around islands and continents and are separated from the shore by narrow, shallow lagoons.

Barrier reefs

Reefs that grow parallel to the coastline and are separated by deeper, wider lagoons. At their shallowest point, they can reach the water’s surface, forming a “barrier” to navigation.

Atolls

Rings of coral that create protected lagoons and are usually located in the middle of the sea.

Lakes

Large natural bodies of standing freshwater are formed when precipitation, runoff, or groundwater seepage fills depressions in the Earth’s surface.

Artificial lakes

Strctures constructed for hydroelectric power generation, recreational purposes, industrial and agricultural use, and/or domestic water supply.

Benthic Zone

The bottom of a lake where organisms can tolerate cool temperatures and low oxygen levels.

Limnetic Zone

A well-lit, open surface water, farther from shore, extends to a depth penetrated by light, occupied by phytoplankton, zooplankton, and higher animals; produces food and oxygen that supports most of a lake’s consumers

Littoral Zone

Ecological zone found in coastal environments where land and water meet

Profundal Zone

Deepest layer of freshwater ecosystems that lies below the photic zone (where sunlight penetrates) and is characterized by cold temperatures, darkness, and low oxygen levels.

Oligotrophic (Young Lake)

Aquatic or terrestrial ecosystems with low levels of available nutrients characterized by limited plant growth, low organic matter, and high oxygen content due to the lack of excess organic decomposition.

Mesotrophic (Middle-Aged Lake)

Aquatic ecosystems characterized by moderate levels of nutrients. These environments strike a balance between nutrient-poor and nutrient-rich conditions, supporting a diverse range of organisms

Eutrophic (Old Lake)

Aquatic ecosystems with an excessive abundance of nutrients leading to increased plant growth, often resulting in harmful algal blooms and various environmental challenges.

Stratification

Formation of distinct layers within a body of water with varying densities due to differences in temperature and salinity

Hypolimnion

deepest layer of thermally stratified lakes

Seasonal Turnover

exchange of surface and bottom water in a lake or pond twice a year.

Fall Turnover

The natural phenomenon in stratified lakes of mixing of warmer surface water with colder bottom water within the lake which leads to a more uniform temperature and distribution of nutrients.

Spring Turnover

The natural phenomenon in stratified lakes of mixing cooler surface water with warm bottom water within the lake which leads to a more uniform temperature and distribution of nutrients.

Wetlands

Areas that are covered with water at some point in the year and that support aquatic plants.

Source Zone

Zone that contains headwaters or headwater streams and often begins as springs or snowmelt of cold, clear water with little sediment and relatively few nutrients.

Transition Zone

Zone that contains slower, warmer, wider, and lower-elevation moving streams, which eventually join to form tributaries.

Floodplain Zone

Flat area of land adjacent to a river, stream, or other body of water that is susceptible to flooding during periods of high water levels.

Riparian Areas

Lands adjacent to creeks, lakes, rivers, and streams that support vegetation dependent upon free water in the soil.

Carbon

fundamental element exchanged among the biosphere, geosphere, hydrosphere, and atmosphere and is the basic building block of life and found in carbohydrates, fats, proteins, and nucleic acids.

Ocean Acidification

The ongoing decrease in the pH of the Earth's oceans, disrupting the creation of coral reefs and the viability of externally fertilized egg cells; Occurs when atmospheric carbon dioxide reacts with seawater to form carbonic acid,

Nitrogen

Element that takes up 78% of the atmosphere. Needed for photosynthesis

Nitrogen Cycle

A biogeochemical process through which nitrogen is converted into many forms, consecutively passing from the atmosphere to the soil to organism and back into the atmosphere

Nitrogen Fixation

When atmospheric nitrogen is converted into ammonia (NH3) or nitrate ions (NO3–), which are biologically usable forms of nitrogen.

Natural Cycling of Nitrogen

Atmospheric nitrogen is converted to nitrogen oxides by lightning and deposited in the soil by rain, where it is assimilated by plants and either eaten by animals or decomposed back to elemental nitrogen by bacteria

Rhizobium

A nitrogen-fixing bacteria

Nitrification

When ammonia (NH3) is converted to nitrite (NO2–) and nitrate (NO3–), which are the most useful forms of nitrogen to plants.

Assimilation

When plants absorb ammonia (NH3), ammonium ions (NH4+), and nitrate ions (NO3–) through their roots.

Ammonification

When decomposing bacteria convert dead organisms and wastes, which include nitrates, uric acid, proteins, and nucleic acids, to ammonia (NH3) and ammonium ions (NH4+)—biologically useful forms.

Denitrification

When anaerobic bacteria convert ammonia into nitrites (NO2–), nitrates (NO3–), nitrogen gas (N2), and nitrous oxide (N2O) to continue the cycle.

Nitrous oxide (N2O)

A greenhouse gas breaks down and destroys atmospheric ozone in the stratosphere.

Phosphorus

Element essential for the production of nucleotides, ATP, fats in cell membranes, bones, teeth, and shells.