Energy Flow 3.2

Autotroph

• Organism that can capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer.

Producer • Organism that can

capture energy from sunlight or chemicals and use it to produce food from inorganic compounds; also called an autotrophs.

Photosynthesis

• Process by which plants and some other organisms use light energy to convert water and carbon dioxide into oxygen and high energy carbohydrates such as sugars and starches.

Chemosynthesis

• Process by which some organisms, such as certain bacteria, use chemical energy to produce carbonhydrates.

Heterotrophs • Organism that obtains energy from the

foods it consumes; also called a consumer.

Consumers• Organism that relies on other organisms

for its energy and food supply.

Herbivores

• Organism that obtains energy by eating only plants.

Carnivores• Organism that obtains energy by eating

animals.

Omnivores • Organism that obtains energy by eating

both plants and animals.

Detritivores • Organism that feeds on plant and animal

remains and other dead matter.

Decomposers• Organism that breaks down and obtains

energy from dead organic matter.

Food Chain• Series of steps in an ecosystem in which

organisms transfer energy by eating and being eaten.

Food Web• Network of complex interactions formed

by the feeding relationships among the various organisms in an ecosystem.

Trophic Level• Step in a food chain or food web.

Ecological Pyramid• Diagram that shows the relative amounts

of energy or matter within each trophic level in a food chain or food web.

Biomass • Total amount of living tissue within a given

trophic level.

Key Concept

• Where does the energy for life processes come from?–Sunlight is the main energy source for

life on Earth.

Key Concept

• How does energy flow through living systems? –Some types of organisms rely on the

energy stored in inorganic chemical compounds.

Key Concept

• How efficient is the transfer of energy among organisms in an ecosystem?–Energy flows through an ecosystem in

one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers).