C4.2 Nutrient Cycling (SL)

A comprehensive set of vocabulary flashcards covering key terms related to nutrient cycling, biomass production, and the carbon cycle.

Nutrient Cycling

The continual reuse of chemical elements within an ecosystem as they move among organisms, soil, water, and air.

Autotroph

An organism that obtains inorganic nutrients from the environment and synthesizes its own carbon compounds (e.g., plants, algae).

Heterotroph

An organism that acquires organic carbon by feeding on other organisms (consumers).

Saprotroph

A decomposer that externally digests dead organic material and releases nutrients back into the environment.

Decomposer

General term for organisms (bacteria, fungi) that break down dead organic matter into simpler inorganic substances.

Biomass

The total mass of living organisms (all carbon compounds) in a given area or ecosystem.

Productivity

The rate at which biomass is generated in an ecosystem, expressed as mass per area per time.

Primary Production

The accumulation of biomass by autotrophs using energy from sunlight or inorganic chemicals.

Gross Primary Production (GPP)

The total amount of biomass produced by autotrophs in a given time period.

Net Primary Production (NPP)

Gross primary production minus the biomass consumed by autotroph respiration; represents stored biomass in plant tissues.

Secondary Production

The generation of biomass by heterotrophs and saprotrophs through feeding on existing organic material.

Net Secondary Production (NSP)

The biomass in consumers after losses from respiration and excretion are subtracted.

Carbon Cycle

The global movement of carbon among the biosphere, hydrosphere, lithosphere, and atmosphere.

Carbon Sink

A reservoir that absorbs more carbon than it releases (e.g., forests, oceans, fossil fuel deposits).

Carbon Source

A process or reservoir that releases more carbon to the atmosphere than it absorbs (e.g., combustion).

Carbon Flux

The transfer of carbon between a source and a sink, often measured in gigatonnes per year.

Biosphere (carbon context)

The sphere where carbon is stored within organic compounds of living organisms.

Hydrosphere (carbon context)

The Earth's water bodies where carbon is stored mainly as dissolved CO₂ and bicarbonate ions.

Lithosphere (carbon context)

The Earth's crust where carbon exists in detritus, sedimentary rocks, and fossil fuels like coal and oil.

Atmosphere (carbon context)

The layer of gases surrounding Earth where carbon accumulates chiefly as CO₂ and CH₄.

Photosynthesis

The process by which photoautotrophs convert CO₂ and H₂O into organic molecules and O₂ using sunlight.

Cellular Respiration

The metabolic process that converts organic molecules into CO₂, H₂O, and ATP, releasing stored energy.

Compensation Point

The light intensity at which the rate of photosynthesis equals the rate of respiration in plants.

Fossil Fuel Formation

The slow conversion of partially decomposed organic matter into peat, coal, oil, or natural gas under anaerobic conditions, heat, and pressure.

Peat

Partially decomposed plant material accumulated in waterlogged wetlands; precursor to coal.

Coal

A solid fossil fuel formed from compressed peat over millions of years under high pressure and heat.

Oil (Petroleum)

A liquid fossil fuel produced from ancient marine organic matter that settled on the seabed.

Natural Gas

A gaseous fossil fuel (mainly methane) formed alongside oil or coal deposits.

Combustion

The exothermic reaction of a fuel with oxygen producing CO₂, H₂O, and energy.

Keeling Curve

The continuous record of global atmospheric CO₂ concentrations showing rising levels and annual fluctuations.