Ecology: Earth's Spheres, Energy Flow, Population Dynamics, and Biogeochemical Cycles

Comprehensive vocabulary flashcards covering Earth's four spheres, biological organization, ecological interactions, energy budgets and trophic transfers, and the water, carbon, and nitrogen cycles.

Atmosphere

The blanket of gases surrounding Earth, made up of Nitrogen ($78\%$), Oxygen ($21\%$), and other gases ($1\%$), which regulates weather, shields the planet from solar radiation, and traps heat to prevent extreme day and night temperatures.

Lithosphere

The solid, rocky outer layer of the Earth, including the crust, soil, mountains, ocean floors, and the tectonic plates that shape the land.

Hydrosphere

All water on, above, and below the Earth's surface, including liquid water in oceans, rivers, and lakes, solid ice glaciers, and water vapour in the air, with approximately $97\%$ being salty ocean water.

Cryosphere

The frozen water on Earth, such as glaciers and icebergs.

Biosphere

The region on Earth where life exists, encompassing the lower atmosphere, water, and soil, and consisting of many distinct ecosystems.

Gaia Hypothesis

A hypothesis proposed by scientist James Lovelock in the 1960s asserting that the biosphere, lithosphere, atmosphere, and hydrosphere function together similarly to living organisms to maintain stable internal conditions over time.

Abiotic Factors

The non-living components of an ecosystem, such as light, water availability, air, space, temperature, nutrients, soil, water acidity, and salinity.

Biotic Factors

The living components and influences within an ecosystem, including animals, plants, insects, birds, and fish, as well as interactions such as predation and competition.

Organism

A single, independent living individual of a species, such as a single deer, oak tree, or robin.

Population

A group of individuals of the same species living and interacting in a specific geographic area at the same time.

Community

Populations of different species living in the same area and interacting with one another.

Ecosystem

A complex system formed by groups of living organisms interacting together with their non-living physical environment.

Carrying Capacity

The maximum number of living individuals of a species or population that an ecosystem can sustain indefinitely without degradation.

Sustainability

The ability of an ecosystem to maintain ecological balance and supply the needs of living organisms indefinitely without compromising future generations.

Limiting Factors

Any abiotic or biotic environmental factor that restricts, reduces, or limits the carrying capacity of an ecosystem.

Radiant Energy

Energy that travels through space as visible light and invisible radiation from the Sun, serving as the primary energy source for most ecosystems.

Thermal Energy

Energy transferred through heating and cooling, formed when radiant energy ($\approx 70\%$) is absorbed by the hydrosphere and lithosphere.

Photosynthesis

The process by which organisms use leaves to absorb light energy, combining carbon dioxide ($CO_2$) and water ($H_2O$) to store chemical energy as glucose (sugar) while releasing oxygen ($O_2$).

Cellular Respiration

The complementary reaction in which glucose (sugar) and oxygen are broken down into carbon dioxide and water to release energy for cellular use.

Producer

An autotrophic organism, such as a plant or alga, that makes its own food through photosynthesis and forms the foundation of most food chains.

Consumer

An organism that obtains its energy and nutrients by eating other organisms.

Decomposer

An organism, such as fungi or bacteria, that breaks down dead organisms and waste materials into simpler substances (water, $CO_2$, and mineral nutrients), recycling nutrients for producers.

Herbivore

A consumer that feeds exclusively or primarily on plants or other producers.

Omnivore

A consumer that feeds on both plants and other animals.

Carnivore

A consumer that feeds exclusively or primarily on other animals.

Scavenger

An animal, such as a vulture, raccoon, or fox, that feeds on the dead remains of other organisms.

Trophic Level

The specific feeding position that an organism occupies within a food chain or energy pyramid.

10% Rule

The ecological principle stating that only approximately $10\%$ of the energy stored at one trophic level is transferred to the next trophic level as biomass.

Food Chain

A linear sequence showing one specific pathway of energy transfer between organisms through feeding.

Food Web

A complex network interconnecting multiple food chains that reflects that most organisms have multiple food sources and predators.

Energy Pyramid

A graphical model representing the energy available at each trophic level, demonstrating that available energy decreases markedly from producers to top predators.

Predator

An organism that hunts, kills, and eats another organism for energy.

Prey

An organism that is hunted, captured, and eaten by a predator.

Intraspecific Competition

Competition for limited resources (such as food, water, territory, or mates) occurring between individuals of the same species.

Interspecific Competition

Competition for shared limited resources (such as food, water, or space) occurring between individuals of different species.

Tolerance Range

The entire range of abiotic conditions (such as temperature or salinity) within which a species can survive.

Optimal Range

The central range of abiotic conditions within a species' tolerance limits where individuals are best adapted, healthiest, and exhibit optimal growth and reproduction.

Biogeochemical Cycle

The continuous pathway and movement of matter and elements through both the biotic and abiotic parts of the environment.

Evaporation

The phase change during the water cycle where liquid water transforms into water vapour.

Condensation

The stage in the water cycle where gaseous water vapour cools and forms liquid droplets, creating clouds.

Precipitation

The return of water from the atmosphere to Earth's surface in the form of rain, snow, sleet, or hail.

Runoff

Water from precipitation that flows across land surfaces into streams, rivers, and lakes.

Infiltration

The process by which water from precipitation seeps and enters downwards into the soil.

Transpiration

The evaporation of water vapour into the atmosphere through the leaves of plants.

Fossil Fuel Formation

The geological process over millions of years where buried remains of dead organisms undergo pressure and heat to form underground carbon reservoirs.

Combustion

The burning of fossil fuels or biomass that rapidly releases stored carbon into the atmosphere in the form of carbon dioxide ($CO_2$).

Sedimentation (Carbon Cycle)

The long-term cycle step in which carbon settles to the ocean floor and becomes incorporated into marine sediments and carbonate rocks.

Weathering (Carbon Cycle)

The chemical and physical breakdown of rocks that releases trapped carbon and transports it into soil, rivers, and oceans.

Nitrogen Fixation

The process in which specialized bacteria convert unreactive atmospheric nitrogen gas ($N_2$) into biologically usable nitrogen compounds.

Nitrification

The microbial conversion of ammonium into nitrites and subsequently into nitrates that can be absorbed by plants.

Assimilation (Nitrogen Cycle)

The uptake of soil nitrogen compounds by plant roots to build plant proteins and DNA, which then move through the food chain.

Ammonification

The process where decomposers convert organic nitrogen found in dead organisms and biological waste back into ammonium.

Denitrification

The microbial conversion of soil nitrates back into atmospheric nitrogen gas ($N_2$), completing the nitrogen cycle.

Algal Bloom

A rapid overgrowth of algae in waterways caused by excess nitrogen and phosphorus runoff from agricultural fertilizers.