Ap Environmental Science Unit 1

Vocabulary flashcards covering key terms from the video notes on energy flow, productivity, biogeochemical cycles, biomes, aquatic zones, and ecological interactions.

Gross Primary Productivity (GPP)

The rate at which producers convert solar energy into stored chemical energy via photosynthesis; typically measured in kcal/m2/year.

Net Primary Productivity (NPP)

GPP minus the energy used by producers for aerobic respiration; the amount of energy stored as biomass that supports consumers.

Photosynthesis

The process by which producers convert light energy into chemical energy stored as sugars.

Respiration (aerobic respiration)

The process by which cells break down stored energy to fuel metabolism, releasing energy for growth and maintenance.

Primary producers

Organisms that produce their own organic matter from inorganic sources (autotrophs).

Autotrophs

Organisms that sustain themselves without consuming organic material from others; they produce their own food.

Primary consumers

Herbivores that eat primary producers.

Secondary consumers

Carnivores that eat herbivores.

Tertiary consumers

Carnivores that eat other carnivores.

Omnivores

Organisms that eat both plants and animals.

Detritivores

Organisms that feed on dead organic material, especially detritus.

Decomposers

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

Phycobiliproteins

Colored pigments in cyanobacteria that help photosynthesis by absorbing light colors chlorophyll does not absorb.

Fluorescence

Property of some compounds to absorb one color of light and emit another color.

Carbon cycle

The movement of carbon between sources and sinks (air, water, organisms, soil); includes photosynthesis, respiration, decomposition and fossil fuel burning.

Reservoir

A source or storage pool where a substance accumulates for varying lengths of time in biogeochemical cycles.

Fossil fuels

Carbon-rich energy sources (coal, oil, natural gas) formed over millions of years and released as CO2 when burned.

Decomposition

The breakdown of dead organic matter by decomposers, returning nutrients to the environment.

Nitrogen cycle

The movement of nitrogen through sources and sinks in ecosystems; largest reservoir is the atmosphere.

Nitrogen fixation

Process by which atmospheric N2 is converted into ammonia or related compounds usable by plants.

Nitrification

Oxidation of ammonia to nitrite and nitrate by specialized bacteria.

Assimilation

Uptake of nitrates or ammonium into plant tissues and incorporation into organic compounds.

Ammonification

Conversion of organic nitrogen from decaying matter into ammonia.

Denitrification

Conversion of nitrates back into nitrogen gas, returning N2 to the atmosphere.

Phosphorus cycle

Movement of phosphorus through ecosystems; largest reservoir is ocean sediments; no atmospheric component; often a limiting nutrient.

Ocean sediments

Major phosphorus reservoir in the phosphorus cycle.

No atmospheric component

Phosphorus cycle lacks a gaseous phase in its return flow, unlike carbon or nitrogen cycles.

Hydrologic cycle

Movement of water through Earth’s systems (solid, liquid, gaseous); largest reservoir is the ocean.

Lotic

Rapidly moving freshwater systems (streams, rivers).

Lentic

Still or slow-moving freshwater systems (lakes, ponds).

Photic zone

Sunlit layer of a body of water where photosynthesis can occur.

Littoral zone

Nearshore zone of a lake or sea where light reaches the bottom; rich in biodiversity.

Benthic zone

Bottom zone of a body of water where organisms live on or in the substrate.

Limnetic zone

Open-water zone in a lake away from the shore; away from the littoral zone.

Profundal zone

Deep, aphotic zone below the limnetic zone in a lake.

Epipelagic zone

The uppermost pelagic zone in the ocean where sunlight is abundant.

Mesopelagic zone

Twilight zone of the open ocean, below the epipelagic, with limited light.

Competitive Exclusion Principle

Two species competing for the same limiting resource cannot coexist indefinitely.

Resource partitioning

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

Mutualism

A symbiotic relationship in which both species benefit.

Commensalism

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

Parasitism

A symbiotic relationship in which one organism benefits at the expense of the other.

Gross Primary Productivity (GPP)

Total energy captured by producers through photosynthesis.

Net Primary Productivity (NPP)

Energy available to consumers after respiration; it determines the carrying capacity of ecosystems for consumers. (\text{NPP} = \text{GPP} - \text{R})

NPP's Geographic Distribution

Highest near the equator (tropics) and lowest near the poles and in deserts.

Trophic level

The position an organism occupies in a food chain (e.g., producer, herbivore, carnivore).

Energy Pyramid

A model illustrating how energy flows through trophic levels, where sunlight provides energy to producers, and only about 10\% of energy passes to the next trophic level.

10% Rule

Only approximately 10\% of energy passes to the next trophic level; the rest is lost to respiration, heat, and maintenance.

Carbon Cycle's Largest Reservoir

The ocean (dissolved CO_2 and carbonates).

Photosynthesis (Carbon Cycle)

Plants, algae, and phytoplankton absorb CO_2 and turn it into glucose.

Respiration (Carbon Cycle)

Organisms break down glucose and release CO_2 back into the atmosphere.

Decomposition (Carbon Cycle)

Decomposers break down dead matter, releasing CO2 or methane (CH4).

Sedimentation & Fossilization (Carbon Cycle)

Carbon gets stored in sediments or fossil fuels for millions of years.

Combustion (Carbon Cycle)

Burning fossil fuels releases stored carbon quickly as CO_2.

Modern Carbon

Currently cycling through organisms, air, and oceans.

Fossil Carbon

Stored for millions of years in coal, oil, and natural gas.

Nitrogen Cycle's Largest Reservoir

The atmosphere (78\% nitrogen gas, N_2).

Nitrogen Fixation

Specialized bacteria or lightning convert N2 gas into ammonia (NH3) or ammonium (NH4^+), which plants can use. (\text{N}2 \rightarrow \text{NH}3/\text{NH}4^+).

Nitrification

Bacteria convert ammonia (NH3) into nitrite (NO2^-), then nitrate (NO3^-). Nitrate is the main form plants absorb. (\text{NH}3 \rightarrow \text{NO}2^- \rightarrow \text{NO}3^-) .

Assimilation (Nitrogen Cycle)

Plants absorb nitrate (NO3^-) and incorporate it into proteins and nucleic acids. Animals get nitrogen by eating plants. (\text{NO}3^- \rightarrow \text{plant proteins}).

Ammonification

Decomposers break down organic matter (dead plants/animals, waste) into ammonia/ammonium. (\text{organic N} \rightarrow \text{NH}3/\text{NH}4^+).

Denitrification

Bacteria convert nitrate (NO3^-) back into N2 gas, returning it to the atmosphere. (\text{NO}3^- \rightarrow \text{N}2 \text{ gas}).

Phosphorus Cycle's Largest Reservoir

Rocks and ocean sediments.

Phosphorus Cycle's Atmospheric Phase

None; phosphorus is naturally scarce.

Weathering (Phosphorus Cycle)

Rocks release phosphate (PO_4^{3-}) into soil/water.

Assimilation (Phosphorus Cycle)

Plants absorb phosphate; animals get it by eating plants.

Limiting Nutrient (Phosphorus)

Phosphorus is a limiting nutrient because ecosystems often can't grow unless it's available.

Hydrologic Cycle's Largest Reservoir

Oceans (97\% of Earth’s water).

Power Source of the Hydrologic Cycle

The sun.

Evaporation

Water from oceans/lakes turns into vapor.

Transpiration

Plants release water vapor from leaves.

Condensation

Water vapor forms clouds.

Precipitation

Water falls as rain, snow, or sleet.

Runoff

Water flows across land into rivers/lakes.

Infiltration

Water soaks into soil, replenishing groundwater.

Biome

A large ecological area defined by climate, flora, and fauna.

High NPP Biomes

Tropical rainforests, estuaries, wetlands.

Low NPP Biomes

Deserts, tundra, open ocean (except upwellings).

Photic Zone

The sunlit layer of water where photosynthesis can occur.

Aphotic Zone

The dark layer of water without photosynthesis; organisms here rely on detritus or chemosynthesis.

Lentic Systems

Aquatic systems with still or slow-moving water (e.g., ponds, lakes, wetlands).

Lotic Systems

Aquatic systems with flowing water (e.g., rivers, streams).

Littoral Zone (Lakes)

The near-shore, shallow part of a lake where plants are rooted.

Limnetic Zone (Lakes)

The open water part of a lake where light penetrates, supporting phytoplankton.

Profundal Zone (Lakes)

The deep, dark part of a lake with little oxygen.

Benthic Zone (Lakes)

The bottom sediments of a lake, inhabited by decomposers.

Epipelagic Zone (Sunlight Zone)

The surface to approximately 200 \text{ m} of the ocean, with enough light for photosynthesis; most marine life lives here.

Mesopelagic Zone (Twilight Zone)

The oceanic zone from 200 \text{–}1,000 \text{ m} with faint light and no photosynthesis.

Bathypelagic Zone (Midnight Zone)

The oceanic zone from 1,000 \text{–}4,000 \text{ m} with complete darkness, where organisms use bioluminescence.

Abyssopelagic Zone

The oceanic zone from 4,000 \text{–}6,000 \text{ m} with near-freezing temperatures and high pressure.

Hadal Zone

Deep ocean trenches below 6,000 \text{ m} with extreme conditions.

Estuaries

Transition areas where rivers meet the sea (freshwater + saltwater mix), highly productive and critical nurseries.

Wetlands

Areas saturated with water seasonally or permanently (swamps, marshes, bogs), known for high NPP, biodiversity, and ecosystem services.

Terrestrial Biomes

Distinct ecological areas defined by similar climate, soil, and vegetation types.

Primary Determinants of Biome Type

Temperature and precipitation.

Tropical Rainforest Biome

Hot, wet year-round climate; nutrient-poor soil; broadleaf evergreen trees; very high NPP.

Savanna (Tropical Grassland) Biome

Warm year-round climate with distinct wet and dry seasons; fertile soil; scattered trees and grasses; moderate to high NPP.

Desert Biome

Hot or cold, very dry climate (less than 25 \text{ cm} rainfall per year); mineral-rich soil, low organic matter; succulents; very low NPP.

Temperate Grassland (Prairie/Steppe) Biome

Moderate rainfall, cold winters, hot summers; very fertile, thick topsoil; grasses; moderate NPP.

Temperate Deciduous Forest Biome

Four distinct seasons, moderate rainfall; nutrient-rich soil due to seasonal leaf fall; deciduous trees; moderate to high NPP.