Biology

Autotroph

An organism that captures energy from sunlight or chemicals and produces its own food from inorganic compounds; also called a producer.

Primary producer

The first producer of energy-rich compounds that are later used by other organisms.

Autotroph

An organism that captures energy from sunlight or chemicals and produces its own food from inorganic compounds; also called a producer.

Primary producer

The first producer of energy-rich compounds that are later used by other organisms.

Photosynthesis

The process used by plants and other autotrophs to capture light energy and convert carbon dioxide and water into oxygen and energy-rich carbohydrates such as sugars and starches.

Chemosynthesis

The process in which chemical energy is used to produce carbohydrates.

Heterotroph

An organism that obtains food by consuming other living things; also called a consumer.

Consumer

An organism that relies on other organisms for its energy and food supply; also called a heterotroph.

Detritus

Material made up of decaying bits of plant and animal material.

Food chain

A series of steps in an ecosystem in which organisms transfer energy by eating and being eaten.

Phytoplankton

Photosynthetic algae found near the surface of the ocean.

Food web

A network of complex interactions formed by the feeding relationships among various organisms in an ecosystem.

Trophic level

Each step in a food chain or web.

Ecological pyramid

An illustration of the relative amounts of energy or matter contained within each trophic level in a given food chain or web.

Biomass

The total amount of living tissue within a given trophic level.

Biogeochemical cycle

The process in which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another.

Nutrient

A chemical substance that an organism needs to sustain life.

Nitrogen fixation

The process of converting nitrogen gas into nitrogen compounds that plants can absorb and use.

Denitrification

The process by which bacteria convert nitrates into nitrogen gas.

Limiting nutrient

A single essential nutrient that limits productivity in an ecosystem.