Academic Decathlon 24-25 Science

Acid Rain

acid deposition that results when rain combines with the air pollutants sulfur dioxide and nitrogen oxides to produce rain with a pH value of 4.0, instead of the pH of 5.0 to 5.5 of normal rain

Aerobic

refers to an environment in which oxygen (O2) is readily available; compare with anaerobic

Age-structure Diagram

a diagram that shows the proportions of individuals in various age classes of a population

Agroforestry

the cultivation of trees in plantations, typically using relatively intensive management practices

Algal Bloom

an event of high phytoplankton biomass

Ammonification

the oxidation of the organically bound nitrogen of dead biomass into ammonium (NH4+)

Anaerobic

refers to an environment in which there is no free oxygen (O2); compare with aerobic

Anthropogenic

occurring as a result of a human influence

Aquifer

groundwater resources in some defined area

Artificial Selection

the deliberate breeding of species to enhance traits that are viewed as desirable by humans

Atmosphere

the gaseous envelope surrounding the Earth, held in place by gravity

Atmospheric Inversion (Temperature Inversion)

a relatively stable atmospheric condition in which cool air is trapped beneath a layer of warmer air

Atmospheric Water

water occurring in the atmosphere in vapor, liquid, or solid forms

Bioaccumulation

the occurrence of chemicals in much higher concentrations in organisms than in the ambient environment; compare with biomagnification

Biodiversity (Biological Diversity)

the richness of biological variation, including genetic variability as well as species and community richness

Biodiversity Crisis

the present era of high rates of species extinction and reduction in multiple levels of biodiversity, from genetic diversity to ecosystems

Biochemical Oxygen Demand (BOD)

the capacity of organic matter and other substances in water to consume oxygen during decomposition

Biomagnification

the tendency for top predators in a food web to have the highest residues of chemicals that persist and move through the food chain; compare with bioaccumulation

Biomass Energy

the chemical potential energy of plant biomass, which can be combusted to provide thermal energy

Biome

a geographically extensive ecosystem, occurring throughout the world wherever environmental conditions are suitable

Biosphere

all life on Earth, plus their ecosystems and environments

Bog

a freshwater wetland of soft, spongy ground consisting mainly of partially decayed plant matter, called peat, that usually develops in cool but wet climates

Boreal Coniferous Forest

a northern forest dominated by coniferous trees, usually species of fir, larch, pine, or spruce

By-catch

inadvertent harvesting of a non-target species

Calorie

a standard unit of energy, defined as the amount of energy needed to raise the temperature of one gram of pure water from 15°C to 16°C; compare with joule

Carnivore (secondary consumer)

an animal that hunts and eats other animals

Carrying Capacity

the number of organisms that can be sustained indefinitely without the habitat becoming degraded

Chaparral

a shrub-dominated ecosystem that occurs in south-temperate environments with winter rains and summer drought

Chromosome

subcellular unit composed of DNA and containing the genetic information of eukaryotic organisms

Clear-Cutting

the harvesting of all economically useful trees from an area at the same time

Climate

the prevailing, long-term, meteorological conditions of a place or region, including temperature, precipitation, wind speed, and other factors; compare with weather

Climate Change

long-term changes in air, soil, or water temperature; precipitation regimes; wind speed; or other climate-related factors

Coal

a carbon-rich, solid fossil fuel mined from sedimentary geological formations

Community

In ecology, this refers to populations of various species that are co-occurring at the same time and place

Compaction

a decrease in the pore space of soil or sediment (or increased bulk density) caused by the passage of heavy machinery

Competition

a biological interaction occurring when the demand for an ecological resource exceeds its limited supply, causing organisms to interfere with each other

Competitor

a species that is dominant in a habitat in which disturbance is rare and environmental stresses are unimportant, so competition is the major influence on evolution and community organization

Compost

partially decomposed, well-humified organic material

Composting

the process of encouraging decomposition of discarded organic matter under warm, moist, oxygen-rich conditions; the product, known as compost, is a useful fertilizer and soil conditioner

Conservation

wise use of natural resources; conservation of renewable resources includes recycling and ensuring that harvesting does not exceed the rate of regeneration of the stock

Contamination

the presence of potentially damaging chemicals in the environment

Control (control treatment)

an experimental treatment that was not manipulated and is intended for comparison with manipulated treatments

Core

Earth's massive interior, made up of hot molten metals

Coriolis Effect

an influence of Earth's west-to-east rotation, which makes winds in the Northern Hemisphere deflect to the right and those in the Southern Hemisphere deflect to the left

Crust

the outermost layer of Earth's sphere, overlying the lithosphere and composed mostly of crystalline rocks

Decay

the decomposition or oxidation of dead biomass, mostly through the actions of microorganisms

Decomposer

a heterotroph that feeds on dead organic matter

Deforestation

a permanent conversion of forest into some other kind of ecosystem, such as agriculture or urbanized land use

Denitrification

the microbial reduction of nitrate
(NO3-) into gaseous N2O or N2

Desert

a temperate or tropical biome characterized by low yearly precipitation, usually receiving less than 25 cm of precipitation per year

Desertification

the increasing aridity of drylands; an environmental change that can make agriculture difficult or impossible

Developed Countries

countries with a relatively well-organized economic infrastructure and a high average per-capita income

Development (economic development)

an economic term that implies improving efficiency in the use of materials and energy in an economy and progress toward a sustainable ecosystem

Discipline

a specific area of study, such as mathematics or music

Disturbance

an episode of destruction of some part of a community or ecosystem

DNA

the biochemical deoxyribonucleic acid, the main constituent of the chromosomes of eukaryotic organisms

Domesticate

to genetically, anatomically, and physiologically modify crops and other species from their wild progenitor species through the selective breeding of preferred individuals

Doubling Time

the time it takes for something to increase by a factor of two (as in population growth)

Dumping

the inappropriate disposal of disused material, for example, by placing solid waste into a sanitary landfill or by discarding liquid waste into a waterbody

Earthquake

a trembling or movement of the earth, caused by a sudden release of geological stresses at some place within the crust

Ecological Footprint

the area of ecoscape (i.e., landscape and seascape) required to supply a human population with the necessary food, materials, energy, waste disposal, and other crucial goods and services

Ecological Pyramid

a model of the trophic structure of an ecosystem, organized with plant productivity on the bottom, that of herbivores above, and carnivores above the herbivores; see also trophic level

Ecology

the study of the relationships between organisms and their environment

Ecosystem

a general term used to describe one or more communities that are interacting with their environment as a defined unit; ecosystems range from small units occurring in microhabitats to larger units such as landscapes and seascapes, and even the biosphere

Ecosystem Approach

a holistic interpretation of the natural world that considers the web-like interconnections among the many components of ecosystems

Ecosystem Service

an ecological function that is useful to humans and to ecosystem stability and integrity, such as nutrient cycling, productivity, and control of erosion

Endangered

In the U.S., this specifically refers to a species listed as endangered under the Endangered Species Act because of its high risk of extinction

Energy

the capacity of a body or system to accomplish work; divided among electromagnetic, kinetic, and potential energies

Environment (the)

(1) refers to influences on organisms and ecosystems, including both non- living (abiotic) and biological factors; (2) an indeterminate word for issues associated with the causes and consequences of environmental damage or with the larger environmental crisis

Environmental Degradation

commonly refers to pollution, disturbance, resource depletion, lost biodiversity, and other kinds of human-caused environmental damage but can also be caused by natural environmental stressors

Environmental Indicators

relatively simple measurements that are sensitive to changes in
the intensity of stressors and are useful for the monitoring of human and nonhuman impacts on the environment

Environmental Justice

the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation and enforcement of environmental laws, regulations, and policies

Environmental Quality

a notion related to the amounts of toxic chemicals and other stressors in the environment, to the frequency and intensity of
disturbances, and to their effects on humans, other species, ecosystems, and economies

Environmental Risk

a hazard or probability of suffering damage or misfortune because of exposure to some environmental circumstance

Environmental Risk Assessment

a quantitative evaluation of the risks associated with an environmental hazard

Environmental Science

an interdisciplinary branch of science that studies the impacts of human activities on environmental systems

Erosion

the physical removal of rocks and soil through the combined actions of flowing water, wind, ice, and gravity

Estuary

a coastal ecosystem that is open to the sea and has habitats transitional between purely marine and freshwater ecosystems

Ethics

norms of conduct that distinguish between acceptable and unacceptable behavior

Eutrophication

increased primary productivity of an aquatic ecosystem resulting from nutrient inputs

Evaporation

the change of water from a liquid to a gas

Evapotranspiration

water losses from a landscape due to evaporation and transpiration

Evolution

genetically based changes in populations of organisms occurring over successive generations

Experiment

a controlled test or investigation designed to provide evidence for, or preferably against, a hypothesis about the natural or physical world

Exposure

the interaction of organisms with an environmental stressor at a particular place and time; often used in environmental health as a measure of the amount of contact of an individual with a specific health risk

Extinct (extinction)

a condition in which a species or other taxon no longer occurs anywhere on Earth

Fauna

a Latin word pertaining to the animal life within a particular environment

First Law of Thermodynamics

a physical principle stating that energy can undergo transformations among its various states, but it is never created or destroyed; thus, the energy content of the universe remains constant; see also Second Law of Thermodynamics

Fission Reaction

nuclear reaction involving the
splitting of heavier, radioactive atoms into lighter
ones, with the release of large quantities of energy

Fitness

the proportional contribution of an individual to the progeny of its population

Flora

a Latin word pertaining to the plant life in a particular environment

Flux

a movement of mass or energy between compartments of a material or energy cycle

Food Chain

a hierarchical model of feeding relationships among species in an ecosystem

Food Web

a complex model of feeding relationships, describing the connections among all food chains within an ecosystem

Forestry

the harvesting of trees and management of post-harvest succession to foster the regeneration of another forest

Fossil Fuels

geological materials, such as coal, petroleum, and natural gas, made from decomposing plants and animals that contain carbon and hydrogen that can be burned for energy

Gene

a region of a chromosome containing a length of DNA that behaves as a specific unit in inheritance and determines the development of a specific trait

Genotype

the genetic complement of an individual organism; see also phenotype

Geothermal Energy

heat in Earth's crust, which can sometimes be used to provide energy for heating or generation of electricity

Glacier

a persistent sheet of ice, occurring in the Arctic and Antarctic and at high altitude on mountains