AP Environmental Science Study Guide Units 1-9 Vocabulary (Key Terms)

Vocabulary flashcards covering key terms from Units 1-9 of AP Environmental Science notes.

Abiotic

Nonliving components of Earth (air, water, minerals, etc.).

Biotic

Living components of Earth (animals, plants, fungi, protists, bacteria) forming the biosphere.

Population (ecology)

A group of organisms of the same species.

Community

Populations of different species that occupy the same geographic area.

Habitat

The area or environment where an organism lives or where an ecological community occurs.

Ecological Niche

The role and position a species has in its environment, including resource use, habitat, and diet.

Competition

Occurs when two individuals compete for resources in the environment.

Resource Partitioning

Coexistence where species share resources without conflict.

Predation

One species feeds on another; drives changes in population size.

Symbiotic Relationships

Close, prolonged associations between two or more different organisms of different species.

Mutualism

Both organisms receive benefits from the relationship.

Commensalism

One organism benefits; the other is neither harmed nor helped.

Parasitism

One organism benefits by harming the other.

Ecotone

A transitional area where two biomes meet.

Edge Effects

In ecotones, high species diversity and density; some species live only on habitat edges.

Ecozones/Ecoregions

Small regions within ecosystems with similar physical features.

Energy Flow

The passage of energy through an ecosystem, starting with solar input and ending in heat.

Bioenergetics

The study of how energy flows through living organisms.

Photosynthesis

Process by which plants and algae convert solar energy into chemical energy, releasing O2.

Light-Dependent Reactions

Photosynthesis stage that converts light energy to chemical energy; reactants: sunlight and H2O; products: O2, ATP, NADPH.

Light-Independent Reactions (Calvin Cycle)

Photosynthesis stage that uses ATP and NADPH to build organic molecules from CO2; product: glucose (C6H12O6).

Cellular Respiration

Metabolic process that releases energy by oxidizing glucose to CO2 and producing ATP.

Autotrophs

Organisms that produce complex organic compounds from inorganic substances; primary producers.

Photoautotrophs

Autotrophs that use light as their energy source.

Heterotrophs

Organisms that consume other organisms for energy and carbon.

Primary Consumers

Herbivores that eat producers.

Secondary Consumers

Organisms that eat primary consumers (carnivores/omnivores).

Tertiary Consumers

Top-level predators that eat secondary consumers.

Producers

Autotrophs that form the base of the food chain.

Saprotrophs

Decomposers that feed on dead or decaying organic matter.

Decomposers

Organisms that break down dead matter, returning nutrients to the ecosystem.

Detritivores

Organisms that ingest detritus (dead organic matter) for energy.

Food Chain

A linear sequence showing energy flow from producers to consumers.

Energy Pyramid

Diagram showing how energy decreases at each successive trophic level.

Food Webs

A network of feeding relationships showing multiple energy pathways.

Biodiversity

The number and variety of organisms in a world, habitat, or ecosystem.

Evolution

Change in the population’s genetic composition over time.

Natural Selection

Differential survival and reproduction of individuals due to advantageous traits.

Charles Darwin

Scientist credited with developing the theory of natural selection (Father of Evolution).

Genetic Drift

Random changes in allele frequencies in a population.

Phylogenetic Tree

A diagram showing evolutionary relationships among species.

Species

A group of organisms capable of breeding with each other but not with other species.

Speciation

Formation of new species from preexisting species.

Extinction

The disappearance of a species. Biological extinction is total; ecological extinction is when a species can no longer perform its ecological role; commercial/economic extinction is when harvesting makes it unviable.

Keystone Species

A species whose presence maintains biotic balance; its loss causes large changes.

Indicator Species

Species used as a health indicator for an ecosystem; sensitive to changes.

Ecological Succession

Pattern of change in community composition over time; primary vs secondary.

Primary Succession

Succession beginning in a virtually lifeless area (e.g., below retreating glacier).

Secondary Succession

Succession following disturbance in which soil remains.

Pioneer Species

First organisms to colonize in succession; tolerant of harsh conditions.

Climax Community

Final, stable stage of succession with a balance of biotic/abiotic factors.

Habitat Fragmentation

Breaking up of a habitat into smaller, isolated patches.

Biotic Potential

The maximum growth rate of a population under ideal conditions.

Carrying Capacity

Maximum population size that the environment can sustain indefinitely.

J-Curve

Exponential growth pattern (unlimited resources).

S-Curve (Logistic Growth)

Growth that starts rapidly then levels off as resources become limiting.

Rule of 70

Estimate of doubling time: 70 divided by the growth rate (as a percent).

R-selected Organisms

Reproduce early with many offspring and little parental care.

K-selected Organisms

Reproduce later with fewer offspring and substantial parental care.

Survivorship Type I

Most offspring survive to old age (e.g., humans).

Survivorship Type II

Uniform death rate across all ages.

Survivorship Type III

Most offspring die young; few survive to old age.

Emigration

Movement of individuals out of a population.

Immigration

Movement of individuals into a population.

Total Fertility Rate (TFR)

Average number of children a woman will bear during her lifetime.

Replacement Birth Rate

Number of births needed to replace a population (often ~2 in many regions).

IPAT Model

I = P × A × T; environmental impact equals population × affluence × technology.

Ecological Footprint

Measure of human demand on Earth's ecosystems.

HIPPCO

Causes of extinction: Habitat destruction/fragmentation, Invasives, Population growth, Pollution, Climate change, Overharvesting/Overexploitation.

Lithosphere

Outer rigid shell of the Earth, including tectonic plates.

Plate Boundaries

Edges where tectonic plates meet: convergent, divergent, transform.

Convergent Boundary

Plates move toward each other; can cause subduction or mountain-building.

Divergent Boundary

Plates move apart; new crust forms.

Transform Fault Boundary

Plates slide past one another in opposite directions.

Subduction

Older, denser plate sinks beneath younger, lighter plate.

Ocean-Continent Convergence

Oceanic plate sinks under continental plate, creating trenches and volcanic activity.

Cascade Range

Example of ocean-continent convergence.

Earthquakes

Vibrations caused by energy release in Earth’s crust.

Epicenter

Initial surface location of an earthquake.

Seismograph

Instrument that measures earthquake magnitude.

Richter Scale

Scale that measures amplitude of the largest seismic waves.

Volcanoes

Geological events due to plate movement.

Active Volcano

Erupted within the last 10,000 years.

Dormant Volcano

Has not erupted recently but is expected to erupt again.

Extinct Volcano

Not expected to erupt again.

Recharging (Volcanoes)

Build-up of pressure between eruptions.

Volcano Types

Shield, Composite, Cinder Cone, Lava Dome.

Shield Volcano

Tall, broad base with gentle slopes.

Composite Volcano

Tall, broad base with steep slopes.

Cinder Cone

Small, short, steep-sloped with a bowl-like crater.

Lava Dome

Small, short, steep-sloped volcanic dome.

Ring of Fire

Major belt of volcanic activity around the Pacific Ocean.

Rift Valley

Divergent boundary where new ocean floor forms.

Hotspots

Plumes of hot mantle causing volcanic chains away from plate boundaries.

Exosphere

Outermost layer of the atmosphere with very thin gases.

Thermosphere

Layer with very thin air; auroras occur here.

Ionosphere

Layer that absorbs X-rays and UV radiation.

Mesosphere

Layer where meteors burn up; very low air pressure.

Stratosphere

Contains the ozone layer; temps rise with altitude.

Troposphere

Lowest layer; weather occurs here; most atmospheric mass.