Energy in Ecosystems and Nutrient Cycles

This set of vocabulary flashcards covers the fundamental concepts of energy flow in ecosystems, including autotrophs, heterotrophs, food webs, ecological pyramids, and the essential nutrient cycles (Water, Carbon, Nitrogen, and Phosphorus).

Autotrophs

Organisms that use sunlight or chemical energy to produce food, also known as primary producers; the term comes from the Greek "auto-" meaning self and "-troph" meaning feeding.

Photoautotrophs

Primary producers, such as plants, algae, and cyanobacteria, that use energy from the sun to undergo photosynthesis and make energy-rich carbohydrates like glucose.

Photosynthesis Equation

$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$: The process where carbon dioxide and water react in the presence of sunlight to create glucose and oxygen gas.

Chemoautotrophs

Organisms, including chemical fixing bacteria and most archaea, that harness energy from inorganic chemicals to synthesize organic carbohydrate molecules through chemosynthesis.

Heterotrophs

Organisms that eat other organisms to obtain energy; also called consumers, from the Greek "hetero" meaning other and "-troph" meaning feeding.

Herbivores

Consumers that eat plants or other producers.

Carnivores

Consumers that eat other animals.

Omnivores

Consumers that eat both plants and animals.

Detritivores

Organisms that feed on dead organic matter, such as earthworms, millipedes, and vultures.

Decomposers

Heterotrophs, like fungi and bacteria, that break down organic material and waste, recycling nutrients back into the ecosystem.

Food Chain

A linear sequence showing how energy and nutrients flow from one organism to another, beginning with a producer and ending with decomposers.

Food Web

A complex network of interconnected food chains that illustrates multiple feeding relationships and how organisms depend on each other for survival.

Trophic Levels

Hierarchical stages in a food chain or food web; the first level consists of producers, the second of primary consumers, the third of secondary consumers, and the fourth of tertiary consumers.

Pyramid of Energy

A representation of energy flow through trophic levels, measured in kilocalories ($kcal$) or joules ($J$), illustrating how energy decreases as it moves up the pyramid.

Ten Percent Rule

A principle stating that only about $10\%$ of the energy from one trophic level is transferred to the next level, while the rest is lost as heat.

Pyramid of Numbers

A representation showing the number of individual organisms at each trophic level; it can be upright or inverted, such as when one large tree supports many herbivores.

Transpiration

A process in the water cycle where water evaporates from the leaves of plants.

Nitrogen Fixation

The process in the nitrogen cycle where bacteria convert atmospheric nitrogen ($N_2$) into ammonia ($NH_3$).

Denitrification

The process in the nitrogen cycle where bacteria convert nitrates back into $N_2$ gas.

Weathering

A key process in the phosphorus cycle where rocks release phosphate into the soil and water.