Environmental Systems: Matter, Energy, and Ecosystems

Comprehensive vocabulary flashcards covering key terms and concepts from Chapter 2 on environmental systems, matter, energy, ecological productivity, and biogeochemical cycles.

System

A network of relationships among components that interact with and influence one another through the exchange of energy, matter, or information.

Lithosphere

The rock and sediment layer of Earth's physical systems.

Atmosphere

The air surrounding planet Earth.

Hydrosphere

All liquid, solid, and gaseous water present on Earth.

Biosphere

The sum of all Earth's living organisms along with the abiotic (nonliving) factors with which they interact.

Feedback loop

A circular process in which a system's output serves as an input to that same system.

Negative feedback loop

A circular process that stabilizes a system by causing output from movement in one direction to act as an input that moves the system in the opposite direction.

Dynamic equilibrium

A state of balance achieved when a system is stabilized by negative feedback loops.

Positive feedback loop

A process that drives a system further toward an extreme rather than stabilizing it.

Eutrophication

The process of nutrient overenrichment in an aquatic system, leading to algal blooms, increased organic matter production, and ecosystem degradation.

Hypoxic zone

An oxygen-depleted area (dead zone) in an aquatic system where insufficient oxygen causes aquatic organisms to suffocate or flee.

Matter

All material in the universe that has mass and occupies space, existing as a solid, liquid, or gas.

Law of conservation of matter

The physical law stating that matter can be transformed from one substance into others, but it cannot be created or destroyed.

Element

A fundamental chemical substance with a specific set of physical and chemical properties.

Nutrients

Elements that organisms require in large amounts to survive and grow, such as carbon, nitrogen, and calcium.

Atom

The smallest chemical unit that maintains the properties of an element.

Protons

Positively charged subatomic particles located within the nucleus of an atom.

Neutrons

Subatomic particles located in an atom's nucleus that lack an electrical charge.

Electrons

Negatively charged subatomic particles that orbit surrounding the nucleus of an atom.

Atomic number

The total number of protons contained in an atom's nucleus.

Mass number

The total number of protons plus neutrons contained within an atom's nucleus.

Isotopes

Atoms of the same element that contain different numbers of neutrons and therefore possess different mass numbers.

Ions

Electrically charged atoms that have gained or lost one or more electrons.

Radioisotopes

Unstable isotopes that shed subatomic particles and emit high-energy radiation until decaying into stable isotopes.

Half-life

The amount of time required for one-half of the atoms in a radioisotope sample to decay.

Molecules

Combinations consisting of two or more atoms bonded together.

Compound

A molecule composed of atoms of two or more different elements.

Ionic bonds

Chemical bonds formed by the electrical attraction between oppositely charged ions, such as in table salt ($NaCl$).

Covalent bond

A chemical bond formed when uncharged atoms share electrons, such as in hydrogen gas ($H_2$).

Solutions

Mixtures in which elements, molecules, or compounds are mixed together without chemical bonding.

pH scale

A logarithmic scale quantifying solution acidity or basicity, where acidic solutions have a $\text{pH} < 7$, basic solutions have a $\text{pH} > 7$, and neutral solutions equal $7$.

Organic compounds

Carbon-based molecules consisting of carbon atoms bonded together, often joined with elements like hydrogen, oxygen, nitrogen, sulfur, or phosphorus.

Inorganic compounds

Chemical compounds that lack carbon-carbon bonds.

Hydrocarbons

Organic compounds containing exclusively carbon and hydrogen atoms, with methane ($CH_4$) being the simplest form.

Polymers

Long chains composed of repeated organic monomer units, including essential biological types such as proteins, nucleic acids, and carbohydrates.

Macromolecules

Large, complex molecules essential to life, encompassing proteins, nucleic acids, carbohydrates, and lipids.

Proteins

Polymers formed from long chains of amino acids that produce tissue structure, store energy, transport materials, act as chemical messengers, or serve as enzymes.

Enzymes

Molecules, typically proteins, that catalyze and accelerate specific chemical reactions in living organisms.

Nucleic acids

Polymers consisting of nucleotide chains (sugar, phosphate, and nitrogen base) such as $DNA$ and $RNA$ that encode hereditary information.

Genes

Specific regions of $DNA$ that code for proteins responsible for performing cellular functions.

Carbohydrates

Biological molecules including simple sugars and sugar polymers used for cellular energy storage (such as starch) and structural support (such as chitin and cellulose).

Lipids

Water-insoluble compounds including fats, oils, phospholipids, waxes, and steroids used for energy storage and cell structures.

Eukaryotes

Organisms whose cells contain a membrane-enclosed nucleus and specialized membrane-enclosed organelles.

Prokaryotes

Single-celled organisms, such as bacteria and archaea, that lack a membrane-enclosed nucleus and organelles.

Energy

An intangible phenomenon capable of altering the position, physical composition, or temperature of matter.

Potential energy

The stored energy of position.

Kinetic energy

The energy of motion.

Chemical energy

Potential energy held within the chemical bonds uniting atoms.

First law of thermodynamics

The physical law stating that energy can change form but cannot be created or destroyed.

Second law of thermodynamics

The physical law stating that energy changes from a more-ordered state to a less-ordered state, increasing entropy.

Entropy

The degree of randomness or disorder in a system.

Autotrophs

Primary producers (such as plants, algae, and cyanobacteria) that absorb solar energy to synthesize organic food molecules.

Photosynthesis

The metabolic process converting solar energy, carbon dioxide, and water into chemical energy stored in sugars according to $6CO_2 + 6H_2O + \text{sunlight} \rightarrow C_6H_{12}O_6 + 6O_2$.

Heterotrophs

Consumers (such as animals, fungi, and microbes) that obtain energy by consuming other organisms.

Cellular respiration

The process by which organisms break glucose bonds using oxygen to release chemical energy according to $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}$.

Ecosystem

All living organisms and nonliving entities occurring and interacting within a specified area.

Primary production

The conversion of solar energy into chemical energy stored in sugars by autotrophs during photosynthesis.

Gross primary production

The total amount of chemical energy synthesized by autotrophs.

Net primary production

The energy remaining after autotrophs perform cellular respiration, calculated as gross primary production minus cellular respiration, which generates plant biomass.

Productivity

The rate at which autotrophic organisms convert solar energy into organic biomass.

Ecotones

Transitional zones where adjacent ecosystems meet and their distinct elements mix.

Landscape ecology

The study of how spatial landscape structures influence the abundance, distribution, and interactions of organisms.

Geographic information systems (GIS)

Computer software applications that overlay diverse spatial data to analyze and visualize ecosystems on large geographic scales.

Patches

Spatial habitat units or ecosystem fragments arranged in mosaic patterns across a landscape.

Ecological modeling

The practice of constructing and testing simplified representations of complex ecological processes to explain and forecast natural dynamics.

Ecosystem services

Essential ecological functions provided by healthy, natural ecosystems that sustain human society and the environment.

Biogeochemical cycle

The continuous movement of nutrients through living organisms and nonliving environmental reservoirs.

Source

A nutrient reservoir that releases more material than it receives.

Sink

A nutrient reservoir that absorbs more material than it releases.

Flux

The rate at which nutrients or materials move between environmental reservoirs over time.

Hydrologic cycle

The continuous movement of liquid, solid, and gaseous water throughout Earth's environment.

Transpiration

The process by which plants release water vapor through their leaves into the atmosphere.

Infiltration

The downward movement of water soaking into soil and rock layers to replenish underground aquifers.

Aquifers

Underground porous rock and soil formations that store groundwater.

Water table

The upper boundary layer of groundwater contained within an aquifer.

Carbon cycle

The biogeochemical pathway regulating the movement of carbon through atmosphere, living organisms, ocean waters, sediments, and fossil fuels.

Nitrogen cycle

The biogeochemical route converting atmospheric nitrogen gas into biologically usable nutrient compounds and back into gaseous form.

Nitrogen fixation

The conversion of inert atmospheric nitrogen gas ($N_2$) into ammonium ($NH_4^+$) by specialized soil bacteria or lightning.

Nitrification

The biological oxidation of ammonium ions ($NH_4^+$) into nitrite ions ($NO_2^-$) and subsequently into plant-usable nitrate ions ($NO_3^-$) by specialized bacteria.

Denitrification

The bacterial conversion of soil or aquatic nitrates ($NO_3^-$) back into gaseous atmospheric nitrogen ($N_2$).

Industrial fixation

The synthetic manufacturing process fixing atmospheric nitrogen into chemical fertilizers on a massive human scale.

Phosphorus cycle

The biogeochemical pathway moving phosphorus through rocks, soil, water, and organisms without a significant atmospheric component.