Energy & Matter Exchange in the Biosphere

Vocabulary flashcards covering ecological systems, thermodynamics, energy flow, biogeochemical cycles, and ecosystem productivity from Unit A notes.

Open System

A system that allows both matter and energy to enter and exit.

Closed System

A system that allows energy to enter and exit, but does not allow matter to enter or exit.

Biosphere

The area of Earth where life exists, composed of the lithosphere (land), hydrosphere (water), and atmosphere (air).

Albedo

The amount or percentage of light reflected back into space from clouds, particles in the atmosphere, land, or water surfaces.

Photosynthesis

The process by which autotrophs convert solar energy into stored chemical energy in carbohydrates, expressed as $\text{CO}_{2(g)} + \text{H}_2\text{O}_{(l)} + \text{energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_{6(s)} + \text{O}_{2(g)}$.

Autotrophs

Organisms, meaning self-feeders, that use solar energy or chemical energy to produce their own food.

Chemosynthesis

The process by which non-photosynthetic primary producers near deep-sea hydrothermal vents make sugars using energy stored in the chemical bonds of hydrogen sulfide.

Heterotrophs

Organisms, meaning other-feeders, that obtain energy and carbohydrates by consuming other organisms.

Cellular Respiration

The process by which producers and consumers release energy stored in the chemical bonds of carbohydrates and convert it into usable energy ($\text{ATP}$), expressed as $\text{C}_6\text{H}_{12}\text{O}_{6(s)} + \text{O}_{2(g)} \rightarrow \text{CO}_{2(g)} + \text{H}_2\text{O}_{(l)} + \text{ATP}$.

Primary Consumer

An organism that eats primary producers; these organisms are herbivores, such as insects, grazers, or zooplankton.

Secondary Consumer

An organism that eats primary consumers; these organisms can be omnivores or carnivores.

Tertiary Consumer

An organism, typically a carnivore, that eats secondary consumers.

Decomposers

Organisms, such as bacteria and fungi, that feed on detritus (dead organic matter or waste) and return nutrients back to the soil.

First Law of Thermodynamics

A physical principle stating that energy cannot be created or destroyed, but can only be transformed from one form to another.

Second Law of Thermodynamics

A physical principle stating that no process of energy conversion is $100\%$ efficient, and waste energy is always released (usually as heat).

Food Chain

A model showing a single, linear pathway through which energy is transferred from organism to organism.

Food Web

A model of energy transfer that shows the interconnected connections among multiple food chains in an ecosystem.

Rule of 10

The principle stating that approximately only $10\%$ of the energy at one trophic level is transferred to the next higher trophic level, while the remaining $90\%$ is lost as heat or used during cellular respiration.

Pyramid of Energy

An ecological pyramid showing the total amount of energy available at each trophic level, measured in Joules ($\text{J}$) or kilojoules ($\text{kJ}$), which can never be inverted.

Pyramid of Numbers

An ecological pyramid based on the total number of individual organisms in the population at each trophic level, which can be inverted if the producer is very large.

Pyramid of Biomass

An ecological pyramid showing the dry mass of organisms per unit area ($\text{g/m}^2$) at each trophic level.

Bioaccumulation

The accumulation of higher concentrations of non-metabolized toxins inside an individual organism's body over the course of its lifetime.

Biomagnification

The increasing concentration of accumulated chemical toxins at successively higher trophic levels within a food web.

Biogeochemical Cycle

The route that water and other chemical nutrients take as they cycle continuously through biotic and abiotic components of the biosphere.

Transpiration

The evaporation of water from plant surfaces into the atmosphere.

Percolation

The downward movement of water soaking into the soil to become part of the water table.

Leaching

The process where surface water moving through soil dissolves and carries away soluble minerals and nutrients.

Polarity of Water

The molecular property where one end of a water molecule has a slight negative charge and the other end has a slight positive charge, allowing hydrogen bonding.

Rapid Cycling of Carbon

The relatively quick movement of carbon through reservoirs, such as through organisms via photosynthesis, cellular respiration, combustion, and decomposition.

Slow Cycling of Carbon

The long-term storage of carbon locked in reservoirs such as sedimentary rock or fossil fuel deposits like peat, coal, oil, and gas.

Nitrogen Fixation

The process where atmospheric nitrogen gas ($\text{N}_2$) is converted into ammonium ($\text{NH}_4^+$) by nitrogen-fixing bacteria or lightning.

Ammonification

The process by which decomposers break down organic waste and dead organisms into ammonia or ammonium.

Nitrification

The biological process in which nitrifying bacteria convert ammonia into nitrite ions ($\text{NO}_2^-$) and then nitrate ions ($\text{NO}_3^-$).

Denitrification

The process in which denitrifying bacteria convert soil ammonium, nitrites, or nitrates back into atmospheric nitrogen gas ($\text{N}_2$).

Eutrophication

The accumulation of excess nutrients (like nitrogen and phosphorus) in aquatic systems, leading to algal blooms, oxygen depletion by decomposers, and fish mortality.

Productivity

The rate at which an ecosystem's producers capture and store energy over time, measured as the mass of new biomass added per unit area per year.

Gaia Hypothesis

The hypothesis proposed by ecologist James Lovelock suggesting that Earth behaves like a self-regulating living organism to maintain internal balance.

Stromatolites

Layered sedimentary rock formations created by ancient photosynthetic cyanobacteria that provide historical evidence of oxygen levels and iron bonding in oceans.