The Physical Environment and Biomes test

Biotic and abiotic factors

Biotic (living) and abiotic (non-living) factors influence the distribution of organisms.

Biotic factors examples

Interactions with other species, predation, and competition.

Abiotic factors examples

Temperature, water, sunlight, wind, rocks, and soil.

Importance of temperature

Affects metabolism and survival; cells freeze below 0°C and denature above 45°C.

Effect of water availability

Organisms require water; desert species have adaptations for water conservation.

Role of salinity

Influences water balance through osmosis; few terrestrial organisms tolerate high salinity.

Sunlight in ecosystems

Drives photosynthesis and influences temperature.

Definition of climate

Long-term prevailing weather patterns in an area.

Macroclimate vs. Microclimate

Macroclimate: large-scale regional patterns; Microclimate: small localized conditions (e.g., under a log).

Cause of global climate patterns

Solar energy distribution and Earth’s tilt/orbit determine temperature and seasons.

Definition of niche differentiation

Species evolve to use different resources to reduce competition.

Biotic factors

Living influences like competition and predation.

Abiotic factors

Non-living environmental components that shape ecosystems.

Climate

Long-term average weather conditions in a region.

Macroclimate

Broad-scale climate trends across large areas.

Microclimate

Localized, small-scale environmental conditions.

Salinity

Salt concentration in water that affects osmotic regulation.

Solar radiation

Primary energy source driving Earth’s climate systems.

Definition of terrestrial biome

Major life zone defined by vegetation, climate, and adapted organisms.

Main control of biome distribution

Climate is the primary factor determining biome locations.

Definition of disturbance

Events like fires, storms, or human activity that change ecosystems.

Definition of climograph

Graph showing mean annual temperature and precipitation for a biome.

Definition of ecotone

Transition zone between two biomes that supports mixed species.

Definition of vertical layering

Multiple forest layers (canopy, understory, ground, roots) that provide diverse habitats.

Tropical forest

Constant warm temperatures, high rainfall; dense canopy and high biodiversity.

Desert

Savanna

Warm year-round; seasonal rainfall; grasses dominate, fires maintain ecosystem.

Chaparral

Cool wet winters, hot dry summers; shrubs and fire-adapted plants.

Temperate grassland

Cold dry winters, warm wet summers; fertile soils, often converted to farmland.

Coniferous forest (Taiga)

Long cold winters, short warm summers; conifers dominate; largest terrestrial biome.

Temperate broadleaf forest

Four seasons; deciduous trees; animals hibernate; year-round precipitation.

Tundra

Cold, low precipitation; permafrost soil; mosses, lichens, migratory animals.

Role of disturbance

Maintains biodiversity and prevents dominance by one species.

Definition of permafrost

Permanently frozen soil that limits plant roots and water infiltration.

Definition of aquatic biomes

Water-based ecosystems (freshwater or marine) covering ~75% of Earth’s surface.

Factors determining aquatic biomes

Light, temperature, salinity, depth, and nutrients.

Definition of zonation

Layering of aquatic systems by light, depth, and temperature.

Definition of thermocline

Temperature boundary separating warm surface water from cold deep water.

Definition of turnover

Seasonal lake mixing that redistributes nutrients and oxygen.

Photic zone

Receives enough light for photosynthesis.

Aphotic zone

Too dark for photosynthesis.

Pelagic zone

Open water above the ocean floor.

Benthic zone

Bottom layer; home to benthos (bottom-dwelling organisms).

Abyssal zone

Deep ocean (2,000–6,000 m); cold, dark, high pressure.

Lakes

Oligotrophic: clear, oxygen-rich; Eutrophic: nutrient-rich, oxygen-poor.

Wetlands

Water-saturated, highly productive; filter pollutants and support biodiversity.

Streams and rivers

Flowing water; oxygen-rich headwaters to nutrient-rich downstream areas.

Estuaries

Transition zones between rivers and oceans; nutrient-rich, nursery areas.

Intertidal zones

Areas between high and low tide; organisms tolerate waves and exposure.

Oceanic pelagic zone

Vast open ocean; phytoplankton and zooplankton dominate; covers 70% of Earth.

Coral reefs

Built by coral skeletons; mutualism with algae; require warm, clear, shallow water.

Marine benthic zone

Seafloor biome; includes deep hydrothermal vents with chemoautotrophic prokaryotes.

Benthos

Organisms living on or near the seabed.

Detritus

Dead organic matter sinking from the surface; food source for deep organisms.

Thermocline

Temperature layer dividing warm and cold water.

Turnover

Seasonal mixing of lake waters that redistributes oxygen and nutrients.