Ap Environmental Chapter 3

Biosphere

The region of our planet where life resides, the combination of all ecosystems on Earth.

Producer

An organism that uses the energy of the Sun to produce usable forms of energy. (Also known as "autotroph.")

Autotroph

See "producer."

Photosynthesis

The process by which producers use solar energy to convert carbon dioxide and water into glucose.

Cellular respiration

The process by which cells unlock the energy of chemical compounds.

Aerobic respiration

The process by which cells convert glucose and oxygen into energy, carbon dioxide, and water.

Anaerobic respiration

The process by which cells convert glucose into energy in the absence of oxygen.

Consumer

An organism that is incapable of photosynthesis and must obtain its energy by consuming other organisms. (Also known as "heterotroph.")

Heterotroph

See "consumer."

Herbivore

A consumer that eats producers. (Also known as "primary consumer.")

Primary consumer

See "herbivore."

Carnivore

A consumer that eats other consumers.

Secondary consumer

A carnivore that eats primary consumers.

Tertiary consumer

A carnivore that eats secondary consumers.

Trophic levels

The successive levels of organisms consuming one another.

Food chain

The sequence of consumption from producers through tertiary consumers.

Food web

A complex model of how energy and matter move between trophic levels.

Scavenger

An organism that consumes dead animals.

Detritivore

An organism that specializes in breaking down dead tissues and waste products into smaller particles.

Decomposers

Fungi and bacteria that convert organic matter into small elements and molecules that can be recycled back into the ecosystem.

Gross primary productivity (GPP)

The total amount of solar energy that producers in an ecosystem capture via photosynthesis over a given amount of time.

Net primary productivity (NPP)

The energy captured by producers in an ecosystem minus the energy producers respire.

Biomass

The total mass of all living matter in a specific area.

Standing crop

The amount of biomass present in an ecosystem at a particular time.

Ecological efficiency

The proportion of consumed energy that can be passed from one trophic level to another.

Trophic pyramid

A representation of the distribution of biomass, numbers, or energy among trophic levels.

Biogeochemical cycle

The movements of matter within and between ecosystems.

Hydrologic cycle

The movement of water through the biosphere.

Transpiration

The release of water from leaves during photosynthesis.

Evapotranspiration

The combined amount of evaporation and transpiration.

Runoff

Water that moves across the land surface and into streams and rivers.

Carbon cycle

The movement of carbon around the biosphere.

Macronutrient

One of six key elements that organisms need in relatively large amounts: nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur.

Limiting nutrient

A nutrient required for the growth of an organism but available in a lower quantity than other nutrients.

Nitrogen cycle

The movement of nitrogen around the biosphere.

Nitrogen fixation

The process that converts nitrogen gas in the atmosphere (N2) into forms of nitrogen that producers can use.

Nitrification

The conversion of ammonia (NH4+) into nitrite (NO2-) and then into nitrate (NO3-).

Assimilation

The process by which producers incorporate elements into their tissues.

Mineralization

The process by which fungal and bacterial decomposers break down the organic matter found in dead bodies and waste products and convert it into inorganic compounds.

Ammonification

The process by which fungal and bacterial decomposers break down the organic nitrogen found in dead bodies and waste products and convert it into inorganic ammonium (NH4+)

Denitrification

The conversion of nitrate (NO3-) in a series of steps into the gases nitrous oxide (N2O) and, eventually, nitrogen gas (N2), which is emitted into the atmosphere.

Leaching

The transportation of dissolved molecules through the soil via groundwater.

Phosphorus cycle

The movement of phosphorus around the biosphere.

Algal bloom

A rapid increase in the algal population of a waterway.

Hypoxic

Low in oxygen.

Dead zone

When oxygen concentration become so low that it kills fish and other aquatic animals.

Sulfur cycle

The movement of sulfur around the biosphere.

Disturbance

An event, caused by physical, chemical, or biological agents, resulting in changes in population size or community composition.

Resistance

A measure of how much a disturbance can affect flows of energy and matter in an ecosystem.

Resilience

The rate at which an ecosystem returns to its original state after a disturbance.

Restoration ecology

The study and implementation of restoring damaged ecosystems.

Watershed

All land in a given landscape that drains into a particular stream, river, lake, or wetland.

Intermediate disturbance hypothesis

The hypothesis that ecosystems experiencing intermediate levels of disturbance are more diverse than those with high or low disturbance levels.