Energy Flow Through Ecosystems

Vocabulary flashcards covering key concepts from the lecture notes on ecosystems, energy flow, production, trophic levels, and biogeochemical cycles.

Ecosystem

The sum of all organisms in a given area and the abiotic factors they interact with.

Biotic factors

Living, or once living, components of an environment.

Abiotic factors

Nonliving (physical and chemical) properties of the environment.

First law of thermodynamics

Energy cannot be created or destroyed, only transferred or transformed.

Conservation of mass

Chemical elements are continually recycled in the environment.

Second law of thermodynamics

Exchanges of energy increase the entropy (disorder) of the universe.

Net energy balance

Net gain of energy yields storage or growth; net loss yields loss of mass and possible death.

Metabolic rate

Total amount of energy an animal uses in a unit of time (measured in calories, heat loss, or O2/CO2 exchange).

Metabolic rate and body mass

Metabolic rate is related to body mass: smaller organisms have higher metabolic rates; larger organisms have lower rates.

Endotherms

Animals that regulate body temperature metabolically to maintain a constant internal temperature.

Ectotherms

Animals that regulate body temperature using external sources such as sun or shade.

Trophic levels

Groups of organisms classified by their main source of nutrition and energy.

Energy flow vs. matter recycling

Energy flows through ecosystems and cannot be recycled; matter cycles via biogeochemical cycles.

Primary producers (autotrophs)

Organisms that use light energy to synthesize organic compounds (plants, algae, photosynthetic plankton; some chemosynthetic bacteria/archaea).

Photosynthesis

Process by which primary producers convert light energy to chemical energy.

Chemosynthesis

Production of organic compounds using chemical energy rather than light; performed by some bacteria and archaea.

Heterotrophs

Organisms that rely on autotrophs for food and cannot make their own.

Primary consumers

Herbivores that eat autotrophs.

Secondary consumers

Carnivores that eat herbivores.

Tertiary consumers

Carnivores that eat other carnivores.

Decomposers

Organisms that get energy from detritus (nonliving organic material) and recycle nutrients; includes fungi and many prokaryotes.

Food chain

The transfer of food energy up the trophic levels in a single linear sequence.

Food web

Linked food chains showing the feeding relationships in a community.

Trophic structure

The arrangement of feeding relationships that determine who eats whom in a community.

Impact of energy changes on trophic levels

Changes in energy availability can alter the number and size of trophic levels; more energy allows more levels, less energy reduces them.

Primary production

The amount of light energy that is converted to chemical energy by primary producers.

Gross primary production (GPP)

Total primary production in an ecosystem.

Net primary production (NPP

GPP minus the energy used by primary producers for respiration (Ra).

Secondary production

The amount of chemical energy in a consumer’s food that is converted to new biomass.

10% transfer efficiency

Approximately 10% of energy is transferred from one trophic level to the next.

Matter cycling

Matter cycles through ecosystems and is recycled; unlike energy, it is not lost from the biosphere.

Biogeochemical cycles

Nutrient cycles that involve both biotic and abiotic factors, including the water, carbon, nitrogen, and phosphorus cycles.

Water cycle

The circulation of water through ecosystems, essential for life and influencing process rates.

Carbon cycle

The cycle of carbon through the atmosphere, biosphere, oceans, and geosphere; carbon is essential for organic molecules.

Nitrogen cycle

The cycle of nitrogen through fixation, mineralization, assimilation, and decomposition; important for amino acids and nucleic acids.

Phosphorus cycle

The cycle of phosphorus essential for nucleic acids, phospholipids, and ATP.