Environmental Science: A Global Concern

Blind Experiment

An experiment in which the subjects do not know whether they are members of the experimental group or the control group.

Closed System

a system in which matter and energy exchanges do not occur across boundaries

Confidence

self-assurance; calm unworried feeling based on a strong belief in one's abilities; strong belief in the ability of a person or plan; trust or faith in a person or thing; something confided; secret; Ex. confidence in your ability; Ex. I'm telling you this in confidence; Ex. exchange confidences about their boyfriends; ADJ. confident

controlled study

Clinical trial in which the subjects are distributed into groups which are either subjected to the experimental procedure (as use of a drug) or which serve as controls

deductive reasoning

reasoning in which a conclusion is reached by stating a general principle and then applying that principle to a specific case (The sun rises every morning; therefore, the sun will rise on Tuesday morning.)

Dependent Variable

The outcome factor; the variable that may change in response to manipulations of the independent variable.

Disturbances

In ecology, a force that changes a biological community and usually removes organisms from it.

Double Blind Experiment

an experiment in which neither the experimenter nor the participants know which participants received which treatment

Emergent Properties

New properties that arise with each step upward in the hierarchy of life, owing to the arrangement and interactions of parts as complexity increases.

Homeostasis

A tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry, such as blood glucose, around a particular level

Hypothesis

a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.

Independent Variable

The experimental factor that is manipulated; the variable whose effect is being studied.

Inductive Reasoning

A type of logic in which generalizations are based on a large number of specific observations.

Manipulative Experiment

an experiment in which the researcher actively chooses and manipulates the independent variable

Mean

the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores

models

Provide an approximation (physical/conceptual representation) of a scientific phenomenon that cannot be observed directly

Natural Experiment

An experiment in which nature, rather than an experimenter, manipulates an independent variable.

Negative Feedback

A primary mechanism of homeostasis, whereby a change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation.

Paradigm Shift

a fundamental change in approach or underlying assumptions.

Positive Feedback

A type of regulation that responds to a change in conditions by initiating responses that will amplify the change. Takes organism away from a steady state.

Reproducibility

making an observation or obtaining a particular result more than once

Resilience

the rate at which an ecosystem returns to its original state after a disturbance

Scientific Consensus

(general agreement among informed scholars) stems from a community of scientists who collaborate in a cumulative, self-correcting process.

Science Literacy

the knowledge and understanding of scientific concepts and processes required for personal decision making, participation in civic and cultural affairs, and economic productivity

Scientific Theory

A well-tested explanation for a wide range of observations or experimental results.

State Shift

a severe disturbance in which the system does not return to normal but instead results in significant changes in some of its state variables

Acids

substances that release hydrogen ions when dissolved in water

Atomic Number

the number of protons in the nucleus of an atom

Atoms

Building blocks of matter

Bases

Compounds that reduce the concentration of hydrogen ions in a solution.

Biological Community

All of the populations of organisms living and interacting in a particular area

Biomass

total amount of living tissue within a given trophic level

Carbon Cycle

The organic circulation of carbon from the atmosphere into organisms and back again

Carbon Sink

A natural environment that absorbs and stores more carbon dioxide from the atmosphere than it releases, which offsets greenhouse gas emissions.

Carnivore

A consumer that eats only animals.

Cell

The basic unit of structure and function in living things

Cellular Respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen

Chemical Energy

A form of potential energy that is stored in chemical bonds between atoms.

Chemosynthesis

process in which chemical energy is used to produce carbohydrates- absence of sunlight

Compound

A substance made up of atoms of two or more different elements joined by chemical bonds

Conservation of Matter

the principle stating that matter is not created or destroyed during a chemical reaction

Consumer

An organism that obtains energy by feeding on other organisms

Decomposer

An organism that breaks down wastes and dead organisms

DNA

A complex molecule containing the genetic information that makes up the chromosomes.

Detritivore

an animal that feeds on dead organic material, especially plant detritus.

Ecology

the branch of biology that deals with the relations of organisms to one another and to their physical surroundings.

Ecosystem

A biological community of interacting organisms and their physical environment.

Elements

A molecule composed of one kind of atom; cannot be broken into simpler units by chemical reactions.

Energy

The ability to do work or cause change

Entropy

a measure of the disorder of a system

Enzymes

Catalysts for chemical reactions in living things

First Law of Thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed.

Food Chain

series of steps in an ecosystem in which organisms transfer energy by eating and being eaten

Food Web

network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem

Heat

Energy in transit due to a temperature difference between the source from which the energy is coming and a sink toward which the energy is going.

Herbivore

organism that obtains energy by eating only plants

Hydrologic Cycle

The cycle through which water in the hydrosphere moves; includes such processes as evaporation, precipitation, and surface and groundwater runoff

Ions

positively and negatively charged atoms

Isotopes

Atoms of the same element that have different numbers of neutrons

Kinetic Energy

the energy an object has due to its motion

Matter

anything that takes up space and has mass

Metabolism

the combination of chemical reactions through which an organism builds up or breaks down materials

Microbiome

all of the microorganisms that live in a particular environment, such as a human body

Molecule

two or more atoms held together by covalent bonds

Nitrogen Cycle

the series of processes by which nitrogen and its compounds are interconverted in the environment and in living organisms, including nitrogen fixation and decomposition.

Omnivore

A consumer that eats both plants and animals

organic compounds

carbon-based molecules

Phosphorus Cycle

The movement of phosphorus atoms from rocks through the biosphere and hydrosphere and back to rocks.

Photosynthesis

process by which plants and some other organisms use light energy to convert water and carbon dioxide into oxygen and high-energy carbohydrates such as sugars and starches

Population

A group of individuals that belong to the same species and live in the same area

Potential Energy

Energy that is stored and held in readiness

Producers

Organisms that produce their own food

Second Law of Thermodynamics

when energy is changed from one form to another, some useful energy is always degraded into lower quality energy (usually heat)

Productivity

The value of a particular product compared to the amount of labor needed to make it.

Scavenger

(n.) a person who collects or removes usable items from waste materials; an animal that feeds on refuse or dead bodies

Species

a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.

Barrier Islands

Coastal islands created from sand deposited by ocean waves and currents in shallow water

Benthic

bottom of an aquatic ecosystem; consists of sand and sediment and supports its own community of organisms

Biome

A group of ecosystems that share similar climates and typical organisms

Bog

marsh, swamp

Boreal Forest

Dense forest of evergreens located in the upper regions of the Northern Hemisphere.

Chaparral

A scrubland biome of dense, spiny evergreen shrubs found at midlatitudes along coasts where cold ocean currents circulate offshore; characterized by mild, rainy winters and long, hot, dry summers.

Cloud Forests

High mountain forests where temperatures are uniformly cool and fog or mist keeps vegetation wet all the time.

Coniferous

referring to vegetation having cones and needle-shaped leaves, including many evergreens, that keep their foliage throughout the winter

Coral Bleaching

Occurs when a coral becomes stressed and expels most of its colorful algae, leaving an underlying ghostly white skeleton of calcium carbonate

Coral Reefs

The most diverse marine biome on Earth, found in warm, shallow waters beyond the shoreline.

Deciduous

(of plants and shrubs) shedding foliage at the end of the growing season

Desert

An extremely dry area with little water and few plants

Estuary

the area where a freshwater stream or river merges with the ocean

Fen

a low and marshy or frequently flooded area of land

Grasslands

a large open area of country covered with grass, especially one used for grazing.

Mangroves

tropical trees that grow along coasts and help maintain the health of coastal environments

Marsh

an area of low-lying land that is flooded in wet seasons or at high tide, and typically remains waterlogged at all times.

Pelagic

Describing organisms that live in the water column away from the ocean bottom.

Phytoplankton

Microscopic, free-floating, autotrophic organisms that function as producers in aquatic ecosystems

Salt Marsh

temperate-zone estuary dominated by salt-tolerant grasses above the low-tide line and by seagrasses under water

Savannas

a region of grassland with scattered trees lying between the equatorial forest and the hot deserts in either hemisphere.

Swamp

A wetland ecosystem in which shrubs and trees grow

Taiga

biome with long cold winters and a few months of warm weather; dominated by coniferous evergreens; also called boreal forest

Thermocline

a layer in a large body of water, such as a lake, that sharply separates regions differing in temperature, so that the temperature gradient across the layer is abrupt.