Unit 1 The Living World: Ecosystems

Vocabulary flashcards covering key ecosystem concepts, biotic/abiotic components, cycles, biomes, trophic levels, and marine/aquatic zones from Unit 1.

Ecosystem

A community of living organisms in conjunction with the non-living components of their environment, interacting as a system (biotically and abiotically).

Biotic

Living components of an ecosystem (plants, animals, microbes, etc.).

Abiotic

Non-living physical/chemical factors in an environment (temperature, sunlight, water, soil, etc.).

Producer

Organisms that synthesize their own food via photosynthesis (plants, photosynthetic algae, phytoplankton); autotrophs."

Predator-prey relationship

A biotic interaction where predators hunt and kill prey; prey availability influences predator numbers.

Symbiosis

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

Mutualism

A symbiotic relationship in which both species benefit and increase their survival/reproduction.

Commensalism

A relationship in which one species benefits while the other is unaffected.

Parasitism

A relationship where one organism (the parasite) benefits at the expense of the host, which is harmed.

Competition

When individuals or species fight for the same limiting resource, affecting population growth.

Limiting resource

Any resource that constrains a population's size or growth.

Resource partitioning

Using limiting resources in different ways, places, or times to reduce competition.

Intraspecific competition

Competition within the same species for the same resources.

Trophic levels

The hierarchical feeding levels in an ecosystem: producers, primary consumers, secondary consumers, tertiary consumers (and detritivores/decomposers in broader views).

Primary producer

Another term for producers; autotrophs that convert energy to biomass.

Primary consumer

Herbivores that eat producers.

Secondary consumer

Organisms that eat primary consumers (carnivores/omnivores).

Tertiary consumer

Top predators that eat secondary consumers.

Detritivore

Organisms that feed on detritus or dead organic matter.

Decomposer

Organisms that break down dead material, returning nutrients to the system.

10% rule

Ecological efficiency; only about 5–20% (averaging ~10%) of energy is transferred to the next trophic level.

Gross Primary Productivity (GPP)

Total amount of energy captured by producers via photosynthesis.

Net Primary Productivity (NPP)

GPP minus the energy used by producers for respiration; energy available to higher trophic levels.

Carbon cycle

Movement of carbon among sources and sinks (biogeochemical cycle); includes photosynthesis, respiration, decomposition, burial; carbon reservoirs include atmosphere, oceans, soils, rocks, fossils.

Nitrogen cycle

Movement of nitrogen among reservoirs through fixation, ammonification, nitrification, assimilation, and denitrification; atmosphere is a major reservoir (~78%).

Phosphorus cycle

Movement of phosphorus through ecosystems; no atmospheric phase; slow cycle driven by weathering of rocks; phosphorus is a limiting nutrient.

Hydrologic (water) cycle

Movement of water through atmosphere, surface, and groundwater via evaporation, condensation, precipitation, infiltration, runoff; oceans are the primary reservoir.

Climatographs

Climate diagrams (mean temperature and precipitation by month) used to describe and compare biomes.

Biome

A large geographic area with a characteristic climate and dominant life forms (e.g., rainforest, desert, tundra, etc.).

Tropical rainforest

Biome with year-round warmth and very high precipitation; high primary productivity and biodiversity.

Desert

Biom with very low precipitation; arid conditions; organisms adapted to dryness.

Tundra

Cold, harsh biome with permafrost and limited vegetation; low productivity.

Taiga (Boreal forest)

Cold biome with long winters and coniferous trees; moderate to high latitude precipitation.

Temperate deciduous forest

Biome with four seasons and broadleaf trees; moderate climate and precipitation.

Grassland / Savanna

Biome dominated by grasses; Savanna includes scattered trees and seasonal rainfall.

Photic zone

Sunlit layer of an aquatic environment where photosynthesis occurs.

Aphotic zone

Dark layer of an aquatic environment with insufficient light for photosynthesis.

Littoral zone

Nearshore shallow zone in freshwater or near-shore in marine systems where light reaches the bottom.

Benthic zone

Bottom region of an aquatic system, where organisms live on or in the substrate.

Biomagnification

Increase in concentration of a substance up the food chain.

Bioaccumulation

Accumulation of substances within an organism over time.