A posterior segment of an animal that usually houses the organs of
digestion and excretion.


Nonliving or not containing any living organisms.

Abiotic factors

Environmental influences produced other than by living organisms; for example, temperature, wind patterns, humidity, pH, substrate rock type, and other physical and chemical influences.

AbomasumThe final compartment of the ruminant stomach, also known as the fourth or true stomach of the cow, comparable in function to the simple-stomached animals.


Aboral surface

The surface opposite the mouth on an echinoderm.

Abscisic acid

A hormone in plants that helps regulate the growth of buds and
the germination of seeds.

Abscission zone

The area at the base of a leaf petiole where the leaf breaks off
from the stem.


In digestion, the movement of nutrients to the circulatory system.

Accessory pigment

A pigment that absorbs light energy and transfers energy to
chlorophyll a in photosynthesis.


The latin name for a genus of raptors, the short winged hawks of classic falconry, such as goshawks or cooper's.


The process of an organism’s adjustment to an abiotic factor.



adjustment to altered environmental conditions.

Acid fallout

Molecules of acid formed from reactions high in the atmosphere involving nitrogen, sulfur oxides, and water vapor that settle out of the atmosphere without any additional water.

Acid rain

The precipitation of sulfuric acid and other acids as rain. The acids form when sulfur dioxide and nitrogen oxides released during the combustion of fossil fuels combine with water and oxygen in the atmosphere.


An inflammatory disorder of the sebaceous glands characterized by skin
lesions in the form of pimples, blackheads, and sometimes cysts.


An animal with no coelom, or body cavity.


The volume of water that would cover one acre of land to a depth of one foot. An acre foot is the basic measure of agricultural water use.


One of the two protein filaments in a muscle cell that function in


A member of a class of bacteria characterized as rod-shaped monerans that form branched filaments.

Activation Energy

Amount of energy required for a chemical reaction to start
and to continue on its own.

Active Transport

The movement of a substance across a cell membrane against a
concentration gradient; requires the cell to expend energy.


An antiviral drug.


An inherited trait that increases an organism’s chance of survival in a particular environment.

Adaptive Radiation

An evolutionary pattern in which many species evolve from
a single ancestral species.


A nitrogen-containing base that is a component of a nucleotide.

Adenosine Diphosphate (ADP)

A substance involved in energy metabolism formed by the breakdown of adenosine triphosphate.

Adenosine Triphosphate (ATP)

A molecule present in all living cells and acting as an energy source for metabolic processes.


The attractive force between unlike substances.



Adrenal Gland

An endocrine gland located on the top of a kidney.

Adrenaline Epinephrine

A hormone secreted by the adrenal medulla that raises
the level of glucose in the blood, increases the heartbeat, and raises blood

Adrenocorticotropic Hormone

A hormone that stimulates the adrenal cortex.


An organism that utilizes atmospheric oxygen in its metabolic pathways.

Aerobic Respiration

The process in which cells make ATP by breaking down
organic compounds, with oxygen as the final electron acceptor.

Afferent Neuron

A neuron that conducts impulses toward the central nervous system.

AflatoxinToxin produced by the fungi Aspergillus flavus and Aspergillus parasiticus.



A crop damaging carcinogen that is produced by mold in stored crops. It is prominent in crops that are stored while still moist.


The remains of the placenta and the amnion, expelled from the mother’s body following birth.


A gel-like base for culturing microbes; extracted from the cell walls of red algae.

Age Structure

The distribution of individuals among different ages in a population.

Agenda 21

The international policy agreed on at the Rio Conference in 1992. Under Agenda 21, countries agreed to work towards sustainable social, economic and environmental development.


The combination of the producing operations of a farm, the manufacture and distribution of farm equipment and supplies and the processing, storage, and distribution of farm commodities.

Agricultural Diversification

Agricultural diversification refers to a shift from one particular cropping system to a varied and multi-cropping system to stabilized farm income (particularlyon small farm holdings) and protects our natural resources.

Agricultural Pollution

Wastes, emissions, and discharges arising from farming activities. Causes include runoff and leaching of pesticides and fertilizers; pesticide drift and volatilization; erosion and dust from cultivation; and improper disposal of animal manure and carcasses.


The art and science of producing crops, raising livestock and their preparation and marketing for use by the human beings.

Agriculture Economy

An economic system based primarily on crop production.

Agriculture Land

Agricultural land is land including arable land, land under permanent crops and land under permanent meadows and pastures.

Agriculture Prices

It is the exchange value of agricultural commodity, determined by buyers and sellers in the market and is expressed in terms of money.


Production of tree crops in a manner similar to agriculture. Also production of trees along with regular crops.

AgronomicAn adjective used to describe plants and plant products. Pertains to agronomy or agricultural plants and things affecting plants.



The science of crop production and soil management.

AI = artificial inseminationThe technique that involves breeding of females without the males being physically present.

Alcoholic Fermentation

The process by which pyruvic acid is converted to ethyl alcohol; the anaerobic action of yeast on sugars.


The disease of addiction to ethanol.


A hormone that helps maintain water and salt balance.


Autotrophic protists.

Alien species

A species occurring in an area outside of its historically known natural range as a result of intentional or accidental dispersal by human activities (also known as an exotic or introduced species).


In amniotic eggs, the membranous sac that contains many blood vessels; in humans, a membrane surrounding the embryo that becomes the umbilical cord.


An alternative form of a gene.

Allele Frequency

The percentage of an allele in a gene pool.


A usually harmless antigen in the environment that is capable of
inducing an allergic reaction.


Immune reaction to an allergen.

All-in all-out systemsA livestock management system in which all animals are introduced into an isolated confinement unit, taken through the appropriate stage of the production cycle and all moved out at the same time. The unit is then cleaned thoroughly and disinfected before a new group comes in.

Alternative Agriculture

Agriculture based on reduced use of chemical fertilizers and pesticides, increased use of crop rotation, enhance sustainability, improve efficiency and profitability and reduce tillage of soil.

Alternative Crops

Non-traditional crops that can be in an area to diversity rotations, and increase income.


Referring to birds that, at hatching, are immature and in need of parental

Altruistic Behavior

Sacrifice by one individual that results in a benefit for
another individual.


One of the tiny air sacs found in the lungs.

ambient air


The air immediately around us.

Amebic Dysentery

A sometimes fatal disease caused by an amoeba that enters the body in contaminated food or water.


In sponges, an amoebalike cell that moves through the body cells, supplying nutrients, removing wastes, and transporting sperm during sexual reproduction.

Amino Acid

A carboxylic acid with an amino group; one of 20 monomers that form proteins.

Amino Acid–Based Hormones

Agroup of hormones that includes proteins, peptides, amino acids, and other forms derived from amino acids.


In the nitrogen cycle, the formation of ammonia compounds.


A procedure used in fetal diagnosis in which fetal cells are removed from the amniotic fluid.


A bulblike sac at the base of the tube foot of an echinoderm that functions in movement.

AnaerobeAn organism capable of living in the absence of free oxygen.

Anal Pore

In protozoa, an opening from which wastes are eliminated.

Analogous Structure

In evolution, structures in more than one organism that have similar appearance and function, but different embryological origin.


A phase of mitosis and meiosis in which the chromosomes separate.

Anatomy Anatomy is the study of the structure of organisms.



A hormone secreted by the testes that controls secondary sex characteristics.


A flowering plant.


A bilaterally symmetrical, segmented worm, such as an earthworm or a leech.


Any plant which completes its entire life cycles and dies within one year or less.

Annual Ring

A yearly growth ring in a woody plant.


The front end of a bilaterally symmetrical organism.


The microsporangium of an angiosperm in which pollen grains are produced.


In plants, algae, and fungi a reproductive structure that produces gametes by mitosis.



The belief that humans hold a special place in nature, being centered primarily on humans and human affairs.


Anthropoid Primate

One of a subgroup of primates that includes monkeys and apes.


A chemical that can inhibit the growth of some bacteria.


A protein produced by B cells that binds to antigens.


A region of tRNA consisting of three bases complementary to the codon of mRNA.

Antidiuretic Hormone

A hormone that helps regulate solute concentration in the blood.


A substance that stimulates an immune response.


The largest artery in the human body; carries blood from the left ventricle to systemic circulation.

Aortic Valve

The semilunar valve on the left side of the heart.

Aphotic Zone

The ocean layer that receives no light.

Apical Dominance

A plant growth pattern in which branches near the shoot tip are shorter than branches farther from the shoot tip.

Apical Meristem

The growing region at the tips of stems and roots in plants.


Any complex part or organ extending from the body.

Appendicular Skeleton

In vertebrates, the bones that form the limbs.


An underground geological formation, or group of formations, containing usable amounts of groundwater that can supply wells or springs for domestic, industrial, and irrigation uses.

Aquifer Depletion

Depletion of water of an aquifer resulting from withdrawal that is greater than natural or artificial recharge.

Arable land

Land that can be cultivated


An arthropod with four pairs of walking legs; a spider, scorpion, mite, or tick.

Arachnoid Membrane

The middle layer of the three sacs that surround the brain and spinal cord.


A prokaryotic organism distinguished from other prokaryotes by the composition of the cell membranes and walls.


In seedless plants, a reproductive structure that produces a single egg by mitosis.

Arid Climate

A dry climate with an annual precipitation usually less than 10 inches and the level of evaporation is greater than the level of precipitation. It is not suitable for crop production without irrigation.


A branch of an artery that gives rise to capillaries.


A vessel that carries blood away from the heart to the body’s organs.

Arthropod Segmented

Animal with jointed appendages and an exoskeleton.

Artificial Fertilizer

A chemical added to soil to enhance crop production.

Artificial Selection

Breeding of organisms by humans for specific phenotypic characteristics.


The fruiting body of an ascomycete.


A gamete-producing structure in ascomycetes.


One of eight haploid cells in an ascus.


A spore sac that forms on the surface of an ascocarp.

Asexual Reproduction

The production of offspring that does not involve the union of gametes.

Asexual reproduction

A method of reproduction in which genetically identical offspring are produced from a single parent; occurs by many mechanisms, including fission, budding, and fragmentation.




An integrated group of species inhabiting a given area; the organisms within a community influence one another's distribution, abundance, and evolution. (A Human Community is a social group of any size whose members reside in a specific locality.)

Asteroid-Impact Hypothesis

The hypothesis that the extinction of the dinosaurs was caused by the impact of a huge asteroid.


A chronic respiratory condition characterized by recurring attacks of wheezing, coughing, and labored breathing.


A disease characterized by the buildup of fatty materials on the interior walls of the arteries.


The mass of air surrounding the Earth.


The simplest particle of an element that retains all the properties of that element.

Atomic Number

The number of protons in an atom.

ATP Synthase

An enzyme that catalyzes the synthesis of ATP from ADP and phosphate.

Atrioventricular Node

A group of nerves in the heart that functions in the heartbeat.

Atrioventricular Valve

A one-way valve separating each atrium from the ventricle beneath it.


An anterior chamber of the heart.

Attenuated Strain

Refers to a preparation of a virus for a vaccine in which the virus is incapable of causing disease under normal circumstances.

Auditory Canal

The tube through which air enters the ear.


Early hominid from the genus australopithecus.

Autoimmune Disease

A disorder in which the immune system attacks the organism’s own cells.

Autonomic Nervous System

A division of the peripheral nervous system that controls the involuntary actions that regulate the body’s internal environment.


A chromosome that is not a sex chromosome.


The ability of an organism to deliberately drop a body part, most often to escape a predator.


An organism that uses energy to synthesize organic molecules from inorganic substances.


Literally, "self eater." Organisms capable of producing their own food.


A plant hormone that regulates cell elongation.


The class of animals that exclusively includes birds

Axial Skeleton

The backbone, skull, and associated bones of vertebrates.


In a neuron, an elongated extension that carries impulses away from the cell body.

Azidothymidine (AZT)

An antiviral drug that inhibits the reverse transcriptase of retroviruses, such as HIV.

B Cell

A lymphocyte that produces antibodies in response to antigens.


A rod-shaped bacterium.

Background extinction rate

Normal rate of extinction -- as a natural part of the evolutionary process -- of various species as a result of changes in local environmental conditions and the actions of natural evolutionary forces. Extinctions not caused or contributed to by the actions of humans.


Microorganisms that break down organic materials in the first stages of composting. It is bacteria that generate the heat associated with hot composting. The three types of bacteria are psychrophilic, mesophyllic, and thermophilic.


A virus that infects bacteria.


One of the keratinous plates that function to filter food from water in some whales.


A branch of a vane in the feather of a bird.


A branch of a barb in the feather of a bird.


Any substance that increases the concentration of hydroxide (OH – ) ions when added to a water solution.

Base Unit

One of seven fundamental units of SI measurement that describe length, mass, time, and other quantities.

Base-Pairing Rule

The rule stating that in DNA, cytosine pairs with guanine and adenine pairs with thymine and in RNA, adenine pairs with uracil.


The fruiting body of a basidiomycete.


A specialized club-shaped reproductive structure that forms on the gills of mushrooms.


To flutter off the fist or perch; an abortive attempt to fly when the bird is restrained by the leash.

Benign Tumor

An abnormal but nonthreatening cell mass.

Benthic Zone

The ocean bottom.


A plant having a two-year life cycle.

Bilateral Symmetry

In animals, a body plan in which the left and right sides mirror each other.


A yellowish fluid secreted by the liver that functions as a fat emulsifier in digestion.

Binary Fission

An asexual cell division of prokaryotes that produces identical offspring.


To grab and hold onto quarry (or volunteers) with the feet.

Binomial Nomenclature

A system of naming organisms that uses the genus name and a species identifier.

Binomial nomenclatureThe two-name system, developed by Carolus Linnaeus (the founder of modern taxonomy), used to assign scientific names to all living things. Homo sapiens, for example, is the scientific name for humans. The first name is the genus name and is always capitalized. This is sort of like your last name... it belongs to several of your close relatives, too, and it shows that you are all closely related. The second name is the species name is always lower case. This is like your first name, which no one else in your circle of relatives posseses and so it uniquely identifies you. Memory tool: you probably know the meanings of the terms generic (i.e. general, broad) and specific (i.e. precise, exact). These terms come from the same origins as genus and species, so recalling their meaning will help you recall the relationship between the two portions of a scientific name.


The absorption of toxic chemicals in plants and animals; some time referred to as bioconcentration.

Biochemical Pathway

A series of chemical reactions in which the product of one reaction is consumed in the next reaction.

Biochemical Pathway

A series of chemical reactions in which the product of one reaction is consumed in the next reaction.


An agent that kills many organisms in the environment.


Able to be broken into simpler chemical compounds by microorganisms. Organic materials are biodegradable.

Biodegradable material

Materials that can be broken down by micro organisms into simple stable compounds such as carbon dioxide and water. Most organic material such as food scraps and paper are biodegradable


 Biodegradation or biotic degradation or biotic decomposition is the chemical dissolution of materials by bacteria or other biological means. The term is often used in relation to ecology, waste management, biomedicine, and the natural environment and is now commonly associated with environmentally friendly products that are capable of decomposing back into natural elements.


Biodiesel is registered with the Environmental Protection Agency as a pure fuel or as a fuel additive and is a legal fuel in commerce. It is typically produced through the reaction of a vegetable oil or animal fat with methanol in the presence of a catalyst to yield glycerin and biodiesel (chemically called methyl esters). It is an alternative fuel that can be used by itself or blended with petroleum diesel for use in diesel engines. Its use can result in substantial reduction of unburned hydrocarbons, carbon monoxide, and particulate matter.


It refers to the variety and the variability among living organisms. These include diversity within species, between species, ecosystems etc.


The theory that living organisms come only from other living

Biogeochemical CycleThe process by which materials necessary for organisms are circulated through the environment.


Study of the geographical distribution of fossils and living organisms.

BiogeographyA branch of geography that deals with the geographical distribution of animals and plants.


Biological control

Controlling plants’ diseases, and animal pests using natural enemies; or inhibiting the reproduction of pests by methods that result in the laying of infertile eggs, etc. Bio-control method may be an alternative or compliment to chemical pest control methods.

Biological resources

Includes genetic resources, organisms or parts thereof, populations, or any other biotic component of ecosystems with actual or potential use or value for humanity.

Biological Species Concept

The principle that defines a species as those organisms that can produce offspring together.

Biologically unique species

A species that is the only representative of an entire genus or family.


The production of light by means of a chemical reaction in an organism.

BiomagnificationThe accumulation/magnification of a substance as it moves through the food.

BiomassThe dry weight of organic material in an ecosystem.


A geographic area characterized by specific kinds of plants and animals.


A major portion of the living environment of a particular region (such as a fir forest or grassland), characterized by its distinctive vegetation and maintained largely by local climatic conditions.


A pesticide that is biological in origin (i.e., viruses, bacteria, pheromones, natural plant compounds) in contrast to synthetic chemicals. Transgenic Bt cotton and corn are biopesticides because Bacillus thuringiensis (Bt) is a naturally occurring soil bacterium that has been genetically engineered into the plants.

Bioregion (bioregional planning)

A territory defined by a combination of biological, social, and geographic criteria, rather than geopolitical considerations; generally, a system of related, interconnected ecosystems.


The portion of the earth and its atmosphere in which living organisms exist or that is capable of supporting life.


The area on and around Earth where life exists.


The area on and around Earth where life exists.

Biosphere reservesBiosphere reserves are a series of protected areas linked through a global network, intended to demonstrate the relationship between conservation and development, established under UNESCO's Man and the Biosphere (MAB) Program.


The living organisms of a region.


Pertaining to any aspect of life, especially to characteristics of entire populations or ecosystems.

Biotic Factor

A living component of an ecosystem.


The ability to walk upright on two legs.


The larva of echinoderms.

Birth Rate

The number of births occurring in a period of time.


An aquatic mollusk with a shell divided into two halves connected by a hinge, such as a clam, oyster, or scallop.


The broad, flat portion of a typical leaf.


The central cavity of a blastula.


A depression formed when cells of the blastula move inward.


A hollow ball of cells formed when a zygote undergoes repeated cycles of cell division.


A disease of plants characterized by quickly developing decay and discoloring of leaves, stems, and flowers.

Blood Alcohol Concentration (BAC)

A measurement of the amount of alcohol in a person’s blood.

Blood Pressure

The force that blood exerts against the walls of a blood vessel.

Blood Type

A specific characteristic of the blood of an individual; A, B, AB, or O, depending on the type of antigen present on the surface of the red blood cell.


The rapid lengthening of internodes caused by gibberellic acid.

Bone Marrow

The soft tissue in the center and ends of long bones where blood cells are produced.

Book Lung

In the abdomen of an arachnid, an organ for gas exchange with parallel folds that resembles the pages of a book.

Botanical pesticides

Pesticides whose active ingredients are plant-produced chemicals such as nicotine, rotenone, or strychnine. Also called plant-derived pesticides.Being "natural" pesticides, as distinct from synthetic ones, they are typically acceptable to organic farmers.


The scientific study of plants.

Bowman’s Capsule

Cup-shaped structure of the nephron of a kidney which encloses the glomerulus and in which filtration takes place.

Brain Stem

The region of the brain that lies posterior to the cerebrum and that connects the cerebrum to the spinal cord.



A group of animals descended from common ancestors and possessing similar characteristics.

BreedA group of animals or plants related by descent from common ancestors and visibly similar in most characteristics. Taxonomically, a species can have numerous breeds.



A male or female kept for reproduction.

Breeding line

Genetic lines of particular significance to plant or animal breeders that provide the basis for modern varieties.


A small tube that branches from the bronchi within the lungs.


One of the two branches of the trachea that enter the lungs.


A plant that has no vascular tissue and does not form true roots, stems, and leaves.


A structure that develops on the stem at the point of attachment of each leaf.

Bud Scale

A modified leaf that forms a protective covering for a bud until it opens.


In fungi, a form of asexual reproduction in which a part of a cell pinches off to produce an offspring cell.


Chemical that neutralizes small amounts of acids or bases added to a solution.

Buffer zone

The region near the border of a protected area; a transition zone between areas managed for different objectives.

Buffer zones

Areas on the edge of protected areas that have land use controls and allow only activities compatible with protection of the core area, such as research, environmental education, recreation, and tourism.

C3 Plant

A plant that fixes carbon exclusively through the Calvin cycle, named for the three-carbon compound that is initially formed.

C4 Plant

A plant that incorporates CO2 into four-carbon compounds.


A hormone that stimulates removal of calcium from the blood.

Calvin Cycle

A biochemical pathway of photosynthesis in which CO2 is converted into carbohydrate.


Crassulacean acid metabolism; a biochemical pathway in certain plants in which CO2 is incorporated into organic acids at night and released for fixation in the Calvin cycle during the day.


Layers of treetops that shade the forest floor.

Capacity Building

The improvement of an organization’s or community’s ability to perform its tasks effectively and confidently. It may include skills training, organizational development and financial resources.


The reaction of a liquid surface with a solid; capillarity allows water to creep up the interior of a narrow vessel.


The protein covering a virus.


In mosses, a sporangium that produces spores; in bacteria, a protective layer of polysaccharides around the cell wall.

Captive breeding

The propagation or preservation of animals outside their natural habitat, involving control by humans of the animals chosen to constitute a population and of mating choices within that population.


A substance found in the cell walls of red algae that is used commercially as a smoothing agent.


A tough covering over the cephalothorax of some crustaceans; the dorsal part of a turtle’s shell.


An organic compound present in the cells of all living things and a major organic nutrient for humans.

Carbon Cycle

Process in which carbon is cycled through the biosphere.

Carbon Fixation

The incorporation of carbon dioxide into organic compounds.


A cancer-causing substance.


Any substance that produces or promotes cancer. This is a key consideration in evaluating the safety of pesticides and other chemicals

Cardiac Muscle

The involuntary muscle of the heart.

Cardiac Sphincter

A circular muscle located between the esophagus and the stomach.

Cardiac Stomach

In an echinoderm, the stomach closer to the mouth.

CardioVascular System

The blood, the heart, and the blood vessels.


A consumer that eats other consumers.


Macro organisms that feed on other animals.


A light-absorbing compound that functions as an accessory pigment in photosynthesis.

Carrier Protein

A protein that transports specific substances across a biological membrane.

Carrying Capacity

The number of individuals of a species that an ecosystem is capable of supporting.

Carrying capacity

The maximum number of individuals of a particular species, that a given part of the environment can maintain indefinitely. Also called biological carrying capacity.


A strong, flexible connective tissue.

Cash crop

Crop grown for cash rather than retained for household that brings money immediately, like cotton, potato and tobacco  etc.



A type of fossil formed when sediments fill in the cavity left by a decomposing organism.


A chemical that reduces the amount of activation energy needed for a reaction but is not a reactant.

Caudal Fin

In fishes, a fin extending from the tail that moves from side to side and amplifies the swimming motions.

Cause and Effect

A relationship between two variables in which a change in one variable leads to a change in the other.


A sac usually found at the beginning of the large intestine.


A membrane-bound structure that is the basic unit of life.

Cell Cycle

The events of cell division; includes interphase, mitosis, and cytokinesis.

Cell Differentiation

The change in morphology, physiology, or function of a cell in relation to its neighboring cells.

Cell Junction

Connection between cells that holds them together as a unit.

Cell Membrane

The lipid bilayer that forms the outer boundary of a cell.

Cell Plate

A membrane that divides newly forming plant cells following mitosis.

Cell Theory

The theory that all living things are made up of cells, that cells are the basic units of organisms, and that cells come only from existing cells.

Cell Wall

A rigid structure that surrounds the cells of plants, fungi, many protists, and most bacteria.

Cell-Mediated Response

Part of an immune response involving a T-cell attack on an antigen.

Cellular Slime Mold

Individual haploid cells that move about like amoebas; member of the phylum Acrasiomycota.

Centers of diversity

The regions where most of the major crop species were originally domesticated and developed. These regions may coincide with centers of origin.

Central Nervous System

The brain and the spinal cord.


A structure that appears during mitosis in animal cells.


A region of the chromosome where the two sister chromatids are held together and which is the site of attachment of the chromosome to the spindle fibers during mitosis.


A dark body containing a centriole in animal cells but not in plant cells; spindle fibers radiate from the centrosome in preparation for mitosis.


Concentration of nerve tissue and sensory organs at the anterior end of an organism.


A free-swimming, predatory mollusk with a circle of tentacles extending from the head; an octopus, squid, cuttlefish, or chambered nautilus.


In arachnids and some crustaceans, a body part formed by the fusion of the head with the thorax.


A posterior portion of the brain that controls movement and muscle coordination.

Cerebral Cortex

The folded outer layer of the cerebrum that controls motor and sensory activities.

Cerebral Ganglion

One of a pair of nerve-cell clusters that serve as a brain at the anterior end of some invertebrates.

Cerebrospinal Fluid

A watery substance that provides a cushion that protects the brain and spinal cord.


The anterior portion of the brain where higher brain functions occur.

Character Displacement

Evolution of anatomical differences that reduce competition between similar species.


A pincerlike mouthpart of some arthropods.


In arthropods, a claw used to capture food and for defense.


An element or compound naturally occurring or created by humans.

Chemical Bond

A chemical attachment between atoms.

Chemical Reaction

The process of breaking chemical bonds, forming new bonds, or both.


The application of a pesticide and/or fertilizer through any irrigation system


A process in chloroplasts and mitochondria in which the movement of protons down their concentration gradient across a membrane is coupled to the synthesis of ATP.


An organism that synthesizes organic compounds using chemicals instead of light.


The production of carbohydrates through the use of energy from inorganic molecules instead of light.


Plant growth in response to a chemical.


A farm implement used to break through and shatter compacted or otherwise impermeable layers of soil.


A carbohydrate that forms part of the arthropod exoskeleton.

Chlorofluorocarbons (CFCs)

 A class of industrial chemicals found to be destroying the ozone layer in the upper atmosphere


A class of light-absorbing pigments used in photosynthesis.


A plastid containing chlorophyll; the site of photosynthesis.


The outer membrane surrounding an embryo.

Chorionic Villi

Fingerlike projections of the chorion that extend into the uterine lining.


One of two identical parts of a chromosome.


The DNA and proteins in the nucleus of a non dividing cell.


DNA and protein in a coiled, rod-shaped form that occurs during cell division.

Chromosome Map

A diagram of allele positions on a chromosome.

Chronic Bronchitis

An inflammation of the bronchi and bronchioles.


The outer covering of a butterfly pupa.


The mixture formed in the stomach from digested food particles and gastric fluid.


An aquatic protist characterized by gametes and zoospores with a single, posterior flagellum.


A short, hairlike organelle that extends from a cell and functions in locomotion or in the movement of substances across the cell surface.

Circulatory System

The system that distributes oxygen and nutrients to cells in all parts of the body.


A condition in which normal liver tissues are replaced by scar tissue.


In fishes, a structure that transfers sperm into the female’s body.


The divisions of the zygote immediately following fertilization.

Cleavage Furrow

The area of the cell membrane that pinches in and eventually separates the dividing cell.


The long term average of weather conditions in an area.


Climate Change

A change which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere. The build-up of manmade gases in the atmosphere traps the suns heat, causing changes in weather patterns on a global scale. The effects include changes in rainfall patterns, sea level rise, potential droughts, habitat loss and heat stress.

Climatic (thermal) stimulusChanges in temperature or other weather related factors that cause a response.

Climax community

The end of a successional sequence; a community that has reached stability under a particular set of environmental conditions.

Closed Circulatory System

A system in which blood is contained within vessels as in the human circulatory system.


A phylum of animals with radially symmetrical bodies, a saclike internal cavity, tentacles, and nematocysts, such as jellyfish, hydras, sea anemones, and corals.


A cell-like droplet formed from dissimilar substances.


The attraction of like molecules to each other.

Cohesion-Tension Theory

States that water is able to move up the stem xylem due to the strong attraction of water molecules to each other.

Collar Cell

A cell lining the inside of sponges that circulates water; also called a choanocyte.


Plant tissue made up of elongated cells with unevenly thickened, flexible walls.


The management of a specific resource (such as a forest or pasture) by a well-defined group of resource users with the authority to regulate its use by members and outsiders.


A self-propelled or tractor-drawn machine which cuts, threshes, and cleans the standing crop which moving across the field. It is adapted to harvesting all the small grains, soybeans, grain sorghums, peanuts, beans, etc. In some areas, the crop is cut and placed in windrows by a swather (windrower), and a combine with a pickup attachment gathers the grain and threshes it at a later date.


Common property resource management

The management of a specific resource (such as a forest or pasture) by a well-defined group of resource users with the authority to regulate its use by members and outsiders.


A group of ecologically related populations of various species of organisms occurring in a particular place and time.


All the populations in one area.


The concept of achieving conservation efficiently by ensuring that a set of areas is assembled with due regard to the additional species that each brings into the network. This is the basis of a critical faunal analysis.


Organic residues, or a mixture of organic residues and soil, which have been piled, moistened, and allowed to undergo biological decomposition for use as a fertilizer.

Concentration Concentration

A measurement of the amount of solute dissolved in a fixed amount of solvent.

Concentration Gradient

The difference in concentration of a substance across space.

Condensation Reaction

A chemical reaction, also called dehydration synthesis, in which one molecule of water is produced.


A photoreceptor within the retina that can produce sharp images and distinguish colors; in gymnosperms, a seed-bearing structure.


An organism that does not regulate its internal environment.


A spore produced during asexual reproduction in ascomycetes


The union of two protists to exchange genetic material.

Conjugation Bridge

In certain algae and fungi, a passageway for the transfer of the genetic information from one organism to another.


The management of human use of the biosphere so that it may yield the greatest sustainable benefit to current generations while maintaining its potential to meet the needs and aspirations of future generations.


The management of human and natural resources to provide maximum benefits over a sustained period of time. In farming, conservation entails matching cropping patterns and the productive potential and physical limitations of agricultural lands to ensure long-term sustainability of profitable production. Conservation practices focus on conserving soil, water, energy, and biological resources. Contour farming, no-till farming, and integrated pest management are typical examples of conservation practices.

Conservation Biology

A branch of biology concerned with preserving biodiversity in natural areas.

Conservation of Biodiversity

The management of human interactions with genes, species, and ecosystems so as to provide the maximum benefit to the present generation while maintaining their potential to meet the needs and aspirations of future generations; encompasses elements of saving, studying, and using biodiversity.

Conservation Practice

Any technique or measure used to protect soil and water resources for which standards and specifications for installation, operation, or maintenance have been developed. Practices approved by the Natural Resources Conservation Service are compiled at each conservation district in its field office technical guide.

Conservation Tillage

Any of several farming methods that provide for seed germination, plant growth and weed control yet maintain effective ground cover throughout the years and disturb the soil as little as possible. No-till is the most restrictive form of conservation tillage. Other practices include ridge-till, strip-till, and mulch-till.

Conservation-tillage farming

Crop cultivation in which the soil is disturbed little (minimum-tillage farming) or not at all (no-till farming) to reduce soil erosion, lower labor costs, and save energy.


A heterotroph that obtains energy from organic molecules made by other organisms.


Polluting or making something impure.

Contour farming

Field operations such as plowing, planting, cultivating, and harvesting on the contour, or at right angles to the natural slope to reduce soil erosion, protect soil fertility, and use water more efficiently.

Contour Feather

A feather that provides coloration, insulation, and a streamlined shape to adult birds.

Contract Crops

Specific crops eligible for production flexibility payments: wheat, corn, sorghum, barley, oats, rice and upland cotton.

Contract farming

Contract farming is defined as a system for the production and supply of agricultural/horticultural produce under forward contracts between producers/suppliers and buyers. The essence of such an arrangement is the commitment of the producer/ seller to provide an agricultural commodity of a certain type, at a time and a price, and in the quantity required by a known and committed buyer.

Contractile Vacuole

An organelle in protists that expels water.

Control Group

In an experiment, a group or individual that serves as a standard of comparison with another group or individual to which it is identical except for one factor.

Controlled Experiment

A test of variables using a comparison of a control group with an experimental group.

Conus Arteriosus

In fishes and frogs, the final chamber of the heart.

Convection Cell

A regional pattern of rising and falling air.

Conventional agriculture

Generally used to contrast common or traditional agricultural practices featuring heavy reliance on chemical and energy inputs typical of large-scale, mechanized farms to alternative agriculture or sustainable agriculture practices.


Convergent Evolution

The process by which unrelated species become more similar as they adapt to the same kind of environment.

Coral bleaching

The loss of color from a coral as it expels its zooxanthellae-usually a stress response.

Coral Reef

A rocklike formation in warm, shallow seas composed of the skeletons of corals.

Cork Cambium

The lateral meristem of a plant; produces cork.


A relationship between two variables in which both variables change together.


In plants, a mature ground tissue located just inside the epidermis; inanimals, the outermost portion of an organ such as the kidney.


A hormone that regulates certain phases of carbohydrate and protein metabolism.

Cost-benefit analysis

Estimates and comparison of short-term and long-term costs (losses) and benefits (gains) from an economic decision. If the estimated benefits exceed the estimated costs, the decision to buy an economic good or provide a public good is considered worthwhile.


A seed leaf in a plant embryo.

Countercurrent Flow

 In gills of fishes, an arrangement whereby water flows away from the head and blood flows toward the head.

Country of origin of genetic resources

The country which possesses those genetic resources in in-situ conditions.

Country providing genetic resources

The country supplying genetic resources collected from in-situ sources, including populations of both wild and domesticated species, or taken from ex-situ sources, which may or may not have originated in that country

Covalent Bond

A bond that forms when two atoms share one or more pairs of electrons.

Cover crops

The leguminous pulses grown at or in advance of the monsoon period in between trees rows to cover the soil from erosion or to draw surplus moisture off e.g. cowpea, ground nut, moong and moth are good cover crops.

Coxal Gland

In some arachnids, an organ that removes wastes and discharges them at the base of the legs.

Cranial Cavity

The area in which the brain rests.

Cranial Nerve

One of the 12 nerves of the head that relay information between the brain and the muscular and sensory structures in the head.


A form of mental retardation caused by hypothyroidism.


A fold of the inner membrane of mitochondria.

Critical faunal analysis

A methodology to identify the minimum set of areas which would contain at least one viable population of every species in a given animal or plant group.

Critical habitat

A technical classification of areas in the United States that refers to habitats essential for the conservation of endangered or threatened species. The term may be used to designate portions of habitat areas, the entire area, or even areas outside the current range of the species.


In earthworms, a structure that stores soil; in birds, a structure that stores food.

Crop Milk

A nutritious milklike fluid secreted by the crop of pigeons and doves to feed their young.

Crop residue

That portion of a plant, such as a corn stalk, left in the field after harvest. ?

Crop Rotation

The practice of growing different crops in recurring succession on the same land, to reduce nutrient depletion of the soil and reliance on pesticides.

Cropping intensity

Cropping intensity refers to the number of crops grown per annum an a given area of land multiplied by hundred

Cropping Pattern

It is the proportion of the area under various crops at a point of time


The exchange of genes by reciprocal segments of homologous chromosomes during meiosis.


A reproductive process in which pollen from one plant is transferred to the stigma of another plant.


An arthropod with mandibles and branched appendages; examples include shrimps, barnacles, crabs, and pill bugs.


A type of lichen that grows as a layer on rocks and trees.


A combination of the words cultivated and variety for a food plant that has a specific distinguishing characteristic, such as Thompson Seedless grapes.


A cultivated variety (genetic strain) of a domesticated crop plant.


A machine used to till the upper portion of the soil, primarily used to destroy weeds or form a moisture retaining mulch

Cultural diversity

Variety or multiformity of human social structures, belief systems, and strategies for adapting to situations in different parts of the world.

Cutaneous Respiration

In some animals, the exchange of gases through the skin.


Plant piece (stem, leaf, or root) removed from a parent plant that is capable of developing into a new plant.


Any of an order of gymnosperms of the family cycadaceae. Cycads are tropical plants that resemble palms but reproduce by means of spermatozoids.


A resistant, thick-walled structure that encloses and protects a dormant organism.


A chemical signal between cells of the immune system.


The division of the cytoplasm of one cell into two new cells.


Plant hormones that promote cell division.


The bursting of a cell.


The region of a cell between the cell membrane and the nucleus.

Cytoplasmic Streaming

The circular motion of the cytoplasm.


A nitrogen-containing base; a pyrimidine of DNA and RNA.


A network of long protein strands in the cytosol that helps maintain the shape and size of a eukaryotic cell.


The gelatinlike aqueous fluid that bathes the organelles on the inside of the cell membrane.

Cytotoxic T cell

A type of T cell that destroys infected body cells.

Day-neutral plant

A plant unaffected by day length.

Death Rate or Mortality Rate

The number of deaths occurring in a period of time.

Debt-For-Nature Swap

A conservation strategy in which a developing country takes steps to preserve its biodiversity in exchange for a reduction in its foreign debt.


A crustacean with five pairs of legs, such as shrimps, crayfish, and lobsters.


Referring to trees that lose their leaves at the end of the growing season.


An organism that obtains nutrients from dead plants and animals.


Removal of trees from a forested area without adequate replanting.


The condition resulting from excessive water loss.

Demographic transition

Hypothesis that countries, as they become industrialized, have declines in death rates followed by declines in birth rates.


A final step in the nitrogen cycle, during which nitrogen gas is returned to the atmosphere.

Density-dependent Factor

A variable related to the density of a population that affects population size.

Density-independent Factor

A variable that affects population size regardless of population density.

Dental Formula

The number, kind, and placement of teeth that are specific for a particular kind of organism.

Deoxyribonucleic Acid (DNA)

A double-helix-shaped nucleic acid.


The result of the extraction of abiotic resources (non-renewable) from the environment or the extraction of biotic resources (renewable) faster than they can be renewed.


A drug that decreases the activity of the central nervous system.

Derived Character

A feature that evolved only within the group under consideration, such as the feathers of birds.

Dermal Tissue System

One type of plant tissue system, which forms the outer covering of plants.

DesalinationThe removal, using any of several processes, of excess salt and other minerals from water in order to obtain fresh water suitable for animal consumption or irrigation, and if almost all of the salt is removed, for human consumption, sometimes producing table salt as a by-product.



An area where rainfall averages less than 25 cm per year.


Conversion of rangeland, rain-fed cropland to desert-like land, with a drop in agricultural productivity of 10% or more. It is usually caused by a combination of overgrazing, soil erosion, prolonged drought, and climate change.

Desired plant community

The plant community that has been determined through a land use or management plan to best meet the plan’s objectives for a site. A desired plant community is consistent with the site’s capability to produce the required resource attributes through natural succession, management intervention, or a combination of both.

Determinate Cleavage

A process in which each cell develops into a specific part of the gastrula.


A consumer that feeds on dead plants and animals.


Macroorganisms that eat decaying matter. Includes ant, beetle, centipede, cricket, earthworm, earwig, enchytraeid worm, millipede, mite, scorpion, slug, snail, spider, springtail, termite, woodlice.


An organism in which the blastopore develops into the anus and the coelom arises by enterocoely and whose embryo has indeterminate cleavage.

Diabetes MellitusA disorder of glucose metabolism caused by insufficient insulin.



A sheet of muscle below the rib cage that functions in inspiration and expiration.


A phase in the heartbeat during which the ventricles relax and the blood flows in from the atria.

Diastolic Pressure

The pressure maintained in the blood when the ventricles are relaxed.


An abundant component of phytoplankton; member of phylum Bacillariophyta.


An angiosperm with two cotyledons, net venation, and flower parts in fours or fives.


In the brain, an area below the cerebral hemisphere that contains the thalamus and the hypothalamus.


A process in which the cells of a multicellular individual become specialized during development.


The process by which molecules move from an area of greater concentration to an area of lesser concentration.


Breaking down food into usable molecules.

Dihybrid Cross

A cross between individuals that involves the pairing of contrasting traits.


The existence of distinct, genetically determined forms of the same species, such as male and female forms.


One of a great variety of terrestrial reptilian forms during the Mesozoic era 245 million to 65 million years ago.


A formation from two amino acids bonded together by means of a condensation reaction.


A cell that contains both chromosomes of a homologous pair.


A double sugar formed from two monosaccharides.


A tractor-drawn implement composed of circular plates arranged at an angle with the soil. Used to prepare the soil for seeding.


The spatial distribution of individuals in a population.

Disruptive Selection

A type of natural selection in which individuals with two extreme forms of a trait have an advantage.


The separating of a molecule into simpler molecules, atoms, radicals, or ions.

dissolved oxygen (DO) content

Amount of oxygen dissolved in a given volume of water at a given temperature and atmospheric pressure; usually expressed in parts per million (ppm).


Divergent Evolution

The process of two or more related species becoming more and more dissimilar.


In taxonomy, a grouping of similar classes of plants.


Hereditary information in the form of a large molecule called deoxyribonucleic acid.

DNA Fingerprint

A pattern of bands made up of specific fragments from an individual’s DNA.

DNA Polymerase

An enzyme that binds to the separated strands of DNA and assembles each strand’s complement in replication.


In the three-domain system of classification, one of three broad groups that all living things fall into on the basis of rRNA analysis.

Domestic price

The price at which a commodity trades within a country,  in contrast to the world price. For those commodities not benefiting from some form of price support, the domestic price is determined by supply and demand. For commodities that receive price support, the domestic price is usually set by the loan rate or some comparable support level that serves as a price floor in the marketplace working in conjunction with any import quota that may be in effect

Domesticated or cultivated species

Species in which the evolutionary process has been influenced by humans to meet their needs.


The adaptation of an animal or plant to life in intimate association with and to the advantage of man.

Dominant Referring

To an allele that masks the presence of another allele for the same characteristic.


A state of decreased metabolism.

Dormant / dormancy

A biological process in which a plant ceases most growth activities and simply maintains existing tissue.


The top of a bilaterally symmetrical animal.

Dorsal Nerve Cord

A neural tube dorsal to the notochord.

Double Cropping

Raising two different crops on the same land in one growing season.

Double Fertilization

In plants, the process in which two types of cell fusion take place in the embryo sac.

Down Feather

One of the soft, fluffy feathers that cover the body of nesting birds and help insulate adult birds.

Down Syndrome

A disorder caused by an extra twenty-first chromosome and characterized by a number of physical and mental abnormalities.


A farm implement for planting seeds which forms a small furrow, deposits the seed in dribbles, covers the seed, and packs soil over it. It can also deposit fertilizer, lime, or other amendments into the soil, alone or with the seed.

Drip irrigation

A method of irrigation used to place irrigation water near plants' roots through pipes or tubes with small holes and eliminate runoff.Through which water trickles drop by drop.


A male bee that develops from an unfertilized egg and functions only to fertilize eggs from the queen.


Any chemical taken into the body that alters the normal processes of either the mind or the body.

Dryland farming

Farming on non-irrigated land. Success is based on rainfall, moisture-conserving tillage, and drought-resistant crops. 

Duchenne Muscular Dystrophy

A form of muscular dystrophy that weakens and progressively destroys muscle tissue.


Disposing of waste illegally by not using bins or official recycling centres, civic amenity sites or landfills.


The first section of the small intestine.

Dura Mater

The outermost of the three sacs that enclose the brain and spinal cord.


A radially symmetrical marine invertebrate with an endoskeleton, a water-vascular system, and tube feet, such as a sea star, a sea urchin, or a sea cucumber.


A method of navigation similar to sonar in which the sound produced bounces off an object used by bats and cetaceans.

Ecological efficiency

The percentage of energy in biomass produced by one trophic level that is incorporated into biomass by the next highest trophic level.

Ecological succession

Process in which communities of plant and animal species in a particular area are replaced over time by a series of different and often more complex communities.

Ecological zones

Characteristic areas within the terrestrial, aquatic (fresh and marine) and aerial habitats that have specific ecosystems .

Ecologically sustainable development

Development in which the total human population size and resource use in the world (or in a region) are limited to a level that does not exceed the carrying capacity or the existing natural capital and is therefore sustainable.


The study of the relationships between organisms and their environments, including, interactions of living organisms with one another and with their non-living surroundings, the flow of matter and energy in an environment, and the structure and functions of nature.



The study of the relationship between organisms and their environment.


All the biotic and abiotic components of an environment.


A basic fundamental unit that includes both living and non-living environment, each influencing the other and each necessary for the maintenance of life.

Ecosystem approach

The Ecosystem Approach is a strategy for the integrated management of land, water and living resources that promotes conservation and sustainable use in an equitable way. The Ecosystem Approach places human needs at the centre of biodiversity management. It aims to manage the ecosystem, based on the multiple functions that ecosystems perform and the multiple uses that are made of these functions. The ecosystem approach does not aim for short-term economic gains, but aims to optimize the use of an ecosystem without damaging it.

Ecosystem diversity

The variety of ecosystems that occurs within a larger landscape, ranging from biome (the largest ecological unit) to microhabitat.


Ecosystem services

Services, vital to the support of human life, provided by intact natural ecosystems. These include the purification of air and water, detoxification and decomposition of wastes, regulation of climate, regeneration of soil fertility, and production and maintenance of biodiversity, from which key ingredients of our agricultural, pharmaceutical, and industrial enterprises are derived. Historically, the nature and value of Earth’s life support systems have largely been ignored until their disruption or loss highlighted their importance.


Travel undertaken to witness sites or regions of unique natural or ecologic quality, or the provision of services to facilitate such travel.


A form of tourism that helps local people make money from an intact ecosystem; tourists pay for nature guides, food, and lodging to tour the ecosystem.


A study of the impact of toxins upon the ecosystems.


The outermost of the three germ layers of the gastrula that develops into the epidermis and epidermal tissues, the nervous system, external sense organs, and the mucous membranes lining the mouth and anus.

EctoparasiteA parasite that lives on a host but does not enter the host’s body.


The region in the cytoplasm located directly inside the cell membranes.


Referring to an animal whose body temperature is determined by the environment.

Efferent Neuron

A neuron that conducts impulses away from the central nervous system.


Contractions of the smooth muscles surrounding the urethra by which semen is forcefully expelled.

El Niño

A disruption of the normal air and water circulation patterns in the Pacific Ocean, leading to unusual weather in many parts of the world.


A venomous snake with two small, fixed fangs in the front of the mouth.


A particle with a negative electric charge that orbits the nucleus of an atom.

Electron Microscope

An instrument that uses a beam of electrons rather than a beam of light to enlarge the image of an extremely small object so that it can be seen.

Electron Transport Chain

Molecules in the thylakoid membrane or inner mitochondrial membrane that use some of the energy in electrons to pump protons across the membrane.

ElementA substance that ordinarily cannot be broken down chemically to form simpler kinds of matter.


A substance that cannot be broken down into simpler substances by chemical means. An element is composed of atoms that have the same atomic number, that is, each atom has the same number of protons in its nucleus as all other atoms of that element.

ElephantiasisA condition of swollen lymphatic vessels in the limbs caused by a parasitic filarial worm.

Embryo SacIn plants, a megagametophyte containing seven cells and eight nuclei.


 A tree with a canopy that forms about the general upper most continuous canopy.

EmigrationThe movement of individuals out of a population.

EmphysemaA degenerative lung disease.

Endangered species

Wild species with so few individual survivors that the species could soon become extinct in all or most of its natural range. IUCN The World Conservation Union (1994) definition, defines species as endangered if the factors causing their vulnerability or decline continue to operate.


Restricted to a specified region or locality.


The occurrence of a species in a particular locality or region.

Endocrine GlandA ductless gland that secretes hormones into the blood.

Endocrine System

A system of glands that transmit chemical messages throughout the body.


The process by which a cell surrounds and engulfs substances.


The innermost of the three germ layers of the gastrula; develops into the epithelium of the pharynx, respiratory tract, digestive tract, bladder, and urethra.


In plants, a specialized layer of cells that regulates substances entering the center of the root.


A parasite that lives inside the host’s body.


The region in the cytoplasm found in the interior of the cell.

Endoplasmic Reticulum

A system of membranous tubules and sacs in eukaryotic cells that functions as a path along which molecules move from one part of the cell to another.


An internal skeleton.


A tissue in angiosperms that provides food for the developing embryo.


A dormant bacterial cell enclosed by a tough coating.


A mutually beneficial relationship between one organism and another that lives within it; the hypothesis of endosymbiosis relating to the evolution of eukaryotes that holds that chloroplasts and mitochondria evolved from endosymbiotic bacteria.


An animal that generates its own body heat through metabolism.


A substance that causes a poison reaction; a compound that makes up part of the cell wall of Gram-negative bacteria.


A region adjacent to a eukaryotic gene that must be activated if the gene is to be expressed.


A neurotransmitter that blocks pain messages to the brain.

Enteric Bacteria

Gram-negative heterotrophic bacteria that inhabit animal intestinal tracts.


The process of mesoderm formation in deuterostomes in which the coelom forms in folded mesoderm.


The study of insects.


All external conditions and factors, living and nonliving (chemicals and energy), that affect an organism or other specified system during its lifetime; the earth's life-support systems for us and for all other forms of life - in effect another term for describing solar capital and earth capital.

Environmental audit

A detailed assessment to check if an organization is following the law, its environmental policies and its Environmental Management System (EMS). The results of the audit help the organization to improve its environmental policies and management system.

Environmental contaminant


A compound present in soil, water or air.

Environmental degradation

Depletion or destruction of a potentially renewable resource such as soil, grassland, forest, or wildlife by using it at a faster rate than it is naturally replenished. If such use is continued, the resource can become nonrenewable (on a human timescale) or non-existent.

Environmental Impact Assessment (EIA)

A method of analysis which attempts to predict the likely repercussions of a proposed major development (usually industrial) upon the social and physical environment of the surrounding area.

Environmental Science

A field of study that uses biological principles to look at the relationships between humans and the Earth.


A catalyst, usually a protein, in living systems.


A decongestant drug derived from Ephedra, a genus of desert shrubs.


A layer of cells that forms a continuous sheet over the outer surface of a plant or animal.


Coiled tube on each testis where sperm complete their development.


A flap of tissue that covers the trachea.


The loss of soil that is caused by wind or water.


A red blood cell.


A tube connecting the mouth or pharynx to the stomach or crop.


Hormone that helps regulate the menstrual cycle.


An aquatic biome found where freshwater streams and rivers flow into the sea; where the tides meet a river current.


A synthetic chemical that breaks down to release ethylene gas; used to ripen fruit.


The study of indigenous knowledge bases regarding plants and their uses.


A gaseous hormone produced by various parts of plants and released into the air.


The lineage of prokaryotes that includes all contemporary bacteria except archaebacteria.


The uncoiled form of chromatin.


Flagellated unicellular algae; many are photosynthetic.


A cell that contains a nucleus and membrane-bound organelles.

Eustachian Tube

A canal that connects the middle ear to the mouth cavity.


The increase of nutrients in an environment.


The process whereby nutrients (e.g. phosphates or nitrates) accumulate in a body of water.


The loss of water from the soil both by evaporation and by transpiration from the plants growing in the soil.  unintentionally (?)


Any gradual change. Organic evolution is any genetic change in organisms from generation to generation.


All the changes that have formed life on Earth from its earliest beginnings to the diversity that characterizes it today.

Excess land

Irrigable land, other than exempt land, owned by any landowner in excess of the maximum acreage limitation (ownership entitlement) under the applicable provision of reclamation law


The process of removing metabolic wastes.

Excurrent Siphon

A tube through which water exits the mantle cavity of a bivalve.

Exergonic Reaction

A chemical reaction that involves a net release of free energy.

Exocrine Gland

A gland that secretes non-hormonal chemicals through a duct.


A process in which a vesicle inside a cell fuses with the cell membrane and releases its contents to the external environment.


Coding region of a eukaryotic gene.


The hard external covering of some invertebrates that provides protection and support.

Exotic species

An organism that exists in the Free State in an area but is not native to that area. Also refers to animals from outside the country in which they are held in captive or free-ranging populations.


A toxic protein secreted by pathogenic bacteria.


The process in which air is forced out of the lungs.

Exponential Growth

A model of population growth in which the birth and death rates are constant.


Pertaining to study or maintenance of an organism or groups of organisms away from the place where they naturally occur. Commonly associated with collections of plants and animals in storage facilities, botanic gardens or zoos

Ex-situ conservation

The conservation of components of biological diversity outside their natural habitats.


Species are those whose members are living and reproducing at the present time.

Extensive agriculture

Maximizing the amount of land use for agriculture.

External Fertilization

The union of gametes outside the bodies of the parents, as in many fishes and amphibians.

External Respiration

The exchange of gases between the atmosphere and the blood.


As defined by the IUCN, extinct taxa are species or other taxa that are no longer known to exist in the wild after repeated search of their type of locality and other locations where they were known or likely to have occurred.


The evolutionary termination of a species caused by the failure to reproduce and the death of all remaining members of the species; the natural failure to adapt to environmental change.


The dying out of a species.

Extreme Halophile

An archaebacterium that lives in very high salt concentrations.


A localized region of pigment in some invertebrates and protozoa that detects changes in the quantity and quality of light.

F1 Generation

The offspring of cross-pollinated P1 generation plants.

Facilitated Diffusion

A process in which substances move down their concentration gradient across the cell membrane with the assistance of carrier proteins.

Facultative Anaerobe

An organism that can metabolize with or without oxygen.

Fallopian Tube

A tube through which eggs move from the ovary to the uterus.

Fallow land

This denotes cultivable land which after abandonment remains uncultivated over long  period called old fallow those kept uncultivated during the current year are called current fallows


In taxonomy, a group of related genera.


Land used for agricultural purposes. The federal government recognizes prime farmland and unique farmland as the most important categories. According to USDA, the United States has had roughly 1 billion acres of farmland. Farmland consists of cropland, pastureland, and grazing land.


A dense bundle of skeletal muscle fibers.

Fatty Acid

A monomer that is part of most lipids.


All of the animals found in a given area.


Waste materials that pass through the anus or cloacal opening.

Feedback Mechanism

A series of events in which the last step controls the first.


A domesticated species that has adapted to existence in the wild state but remains   distinct from other wild species. Examples are the wild horses and burros of the West and the wild goats and pigs of Hawaii.


A process in which cells make a limited amount of ATP by converting glucose into another organic compound, such as lactic acid or ethyl alcohol, in the absence of oxygen.


A compound that provides plants with essential mineral nutrients like nitrogen and phosphorus.


Any organic or inorganic material, either natural or synthetic, used to supply essential elements for plant growth mainly nitrogen, phosphate and potash

Fetal Alcohol Syndrome

A condition characterized by growth and developmental defects affecting some children born to women who drink alcohol during pregnancy.


Referring to a developing human from the end of the eighth week until birth.


The long, sticky threads that function in blood clotting.

Fibrous Root System

A mat of threadlike roots that spread out below the surface of the soil to maximize exposure to water and minerals and to anchor the plant firmly to the soil.


In flowers, the structure that supports the anther.

Filamentous Alga

An alga that has a slender, rod-shaped thallus composed of rows of cells joined end to end.

Filarial Worm

One of a variety of parasitic roundworms that cause elephantiasis in humans and heartworm disease in dogs.

Filter Feeding

The method by which a sessile organism screens food out of the surrounding water.


A type of asexual reproduction in which the organism splits in two and regenerates the parts missing on each new half to produce two whole organisms.

Flame Cell

In a flatworm, a cell that collects excess body water and transfers it to the excretory system.


The common name for any of the dorso–ventrally flattened worms of the phylum Platyhelminthes, such as a planarian, fluke, and a tapeworm.

Flavin Adenine Dinucleotide

A compound that accepts electrons during redox reactions.

Flight Feather

A specialized contour feather on the wing or tail of a bird.


A method of irrigation, where the land is supplied with sufficient water enough to stand above the surface


Organisms of the plant kingdom.

Flora and fauna

The plants and animals that are native to a particular area or period of time.

Fluid Mosaic Model

A model of cell membrane structure representing the dynamic nature of membrane lipids and proteins.


A leaf-shaped parasitic flatworm.


The route followed by migratory birds.

Foliose Lichen

A type of lichen that lives on soil surfaces, where it forms a matlike growth.

Food Chain

Pathway beginning with producers along which energy is transferred from trophic level to trophic level.

Food chain

A group of organisms in which there is a transfer of food energy through a series of repeated eating and being eaten; in an ecosystem, plants and animals are linked together by their nutritional requirements with the help of a food chain.

Food web

The combination of all the feeding relationships that exist in an ecosystem. Most prey species are eaten by many different predators, and most predators eat more than one prey item. As a result, a picture of a trophic system with lines (representing ecological relationships) drawn between predators and prey soon resembles an intricate web.

Food Web

The interconnected food chains in an ecosystem.


An ancient group of shelled sarcodines found in oceans.


The remains or traces of a once-living organism.


A remnant, impression, mineralized mold, amber encasement, or other trace of a once-living organism. Technically, anything that once lived and has been permanently preserved is a fossil, but the most common usage implies great age. This common usage of fossil generally refers to the mineralized remains or impressions, preserved in stone (almost always sedimentary rock), of extinct organisms from past geologic ages.

Fossil fuel

Products of partial of complete decomposition of plants and animals that occur as crude oil, coal, natural gas, or heavy oils as a result of exposure to heat and pressure in earth's crust over millions of years.

Fossil fuels

Fuels – such as coal, gas, peat and oil – that are formed in the ground over a long time from dead plants and animals and are used up once they are burned for energy.

Fossil record

The cumulative taxonomic information and historical perspective provided by the wealth and diversity of fossils and related geologic data stored in the earth's crust.


A crack or break in a bone.


In fungi, a form of asexual reproduction in which individual cells are released that act like spores.

Frame Shift Mutation

A mutation that results in the misreading of the code during translation because of a change in the reading frame.


The mature leaf of a fern.


A mature plant ovary; a modified flower part that encloses a seed or seeds.

Fruiting Body

Spore-bearing structure of a slime mold during reproduction.


A shrublike lichen.


A carotenoid pigment that is one of the primary pigments found in diatoms and brown algae.


A vaporized pesticide used to control pests in soil, buildings and greenhouses, and chambers holding products such as fruits

Functional Group

A structural building block that determines the characteristics of a chemical compound.

Fundamental Niche

The full range of conditions that a species can tolerate and resources it can use.

Fungi Imperfecti or Deuteromycota

A group of fungi whose sexual phase has not been discovered.


Any pesticide used to control, deter, or destroy fungi, which are forms of plant life (including molds and yeasts) that lack chlorophyll and are unable to make their own food (such as the plant pathogen, powdery mildew).


The fused collarbones in a bird’s skeleton; the “wishbone”.

Furrow irrigation

Small, shallow channels guide water across the surface of a leveled field. Crops are typically grown on a ridge or raised bed between the furrows. This is the major irrigation system that is based on gravity

Futures contract

An agreement between two people one who sells and agrees to deliver, and one who buys and agrees to receive a certain kind, quality, and quantity of products to be delivered during a specified delivery month at a specified price


The saclike organ in vertebrates that is connected to the liver that stores bile.


In algae and fungi, a gamete chamber.


A reproductive cell.


An undifferentiated cell that develops into a gamete.


In plants and algae, a multicellular structure that produces gametes.

GanglionA mass of nerve cells.


An alternative fuel made from alcohol from fermented grains mixed with gasoline.

Gastric Cecum

A pocket that branches from the digestive tract and secretes enzymes.

Gastric Fluid

A liquid secreted by gastric glands in the stomach.

Gastric Pit

The open end of gastric glands through which secretions are released into the stomach.


A hormone that stimulates the stomach to secrete digestive enzymes.


In cnidarians, the layer of cells surrounding the gastrovascular cavity.

Gastrointestinal Tract

The digestive tract from the mouth to the anus.


A mollusk that has one or no shell and moves by gliding on a muscular foot; examples include snails, slugs, and nudibranchs.

Gastrovascular Cavity

A digestive chamber with a single opening found in cnidarians, ctenophores, and flatworms.


The cup-shaped embryo formed as the blastula folds inward.

Gel Electrophoresis

Technique used to separate nucleic acids or proteins by size and charge.


An asexual reproductive structure produced by some freshwater sponges.


A segment of DNA that contains coding for a polypeptide or protein; a unit of hereditary information.

Gene Clone

An exact copy of a gene.

Gene Expression

The transcription of DNA into RNA and then into proteins.

Gene Flow

The movement of genes into or out of a population.

Gene Pool

All the genes for all of the traits in a population.

Gene pool

The sum total of all the genes that exist among all the individuals of a species.

Gene Therapy

Treatment of a genetic disorder by introducing a healthy gene into a cell.


A species with a broad niche that can tolerate a wide range of conditions and can use a variety of resources.

Generative Cell

In a pollen grain, the cell that forms two sperm.

Genetic Code

Triplets of nucleotides in mRNA that determine the sequence of amino acids in protein.

Genetic Counseling

The process of informing a couple about their genetic makeup, which has the potential to affect their offspring.

Genetic Disorder

A disease that has a genetic basis.

Genetic Diversity

The amount of genetic variation within a population or species.

Genetic diversity

The variety of genes within a particular population, species, variety, or breed.

Genetic driftA cumulative process involving the chance loss of some genes and the disproportion ate replication of others over successive generations in a small population, so that the frequencies of genes in the population are altered. The process can lead to a population that differs genetically and in appearance from the original population.

Genetic engineering

The artificial transfer of specific genes from one organism to another.

Genetic resources

Genetic material of actual or potential value.


In mushrooms, one of the radiating rows on the underside of the cap; in animals, an organ specialized for the exchange of gases with water.


A muscular region of the digestive tract in birds that crushes food.


Collecting of unharvested crops from the fields, or obtaining agricultural products from farmers, processors, or retailers without charge

Gliding Joint

A joint that allows bones to slide over one another, as in foot bones that flex in walking.

Global warming

The term given to the possibility that Earth's atmosphere is gradually warming because of the greenhouse effect of carbon dioxide and other gases. Global warming is thought by many to be the most serious global environmental issue facing our society.


A cluster of capillaries that receives blood from the renal artery and that is enclosed in Bowman’s capsule.


A hormone that raises the blood glucose level.


A pathway in which glucose is oxidized to pyruvic acid.


A molecule of protein with attached sugar chains.


The process of inserting a scion of a specified plant variety into a stem, root, or branch of another plant so that a permanent union is achieved.

Green manure

 A crop planted with the intention of turning it under for use as organic matter

Green manuring crop

Crops grown during rainy season and buried in to the soil by ploughing just at their flowering stage to add organic matter after their decomposition in the soil e.g. Senji, Guara, Dhaincha, Sanhemp are good manuring crops

Green Revolution

The development and introduction of new varieties of wheat and rice (mainly) that increased yields per acre dramatically in some countries.

Greenhouse effect

A natural effect that traps heat in the atmosphere (troposphere) near the earth's surface. Some of the heat flowing back toward space from the earth's surface is absorbed by water vapor, carbon dioxide, ozone, and several other gases in the lower atmosphere (troposphere) and then radiated back toward the earth's surface. If the atmospheric concentrations of these greenhouse gases rise and are not removed by other natural processes, the average temperature of the lower atmosphere will gradually increase.

Greenhouse gasesGases in the earth's lower atmosphere (troposphere) that cause the greenhouse effect. Examples are carbon dioxide, chlorofluorocarbons, ozone, methane, water vapor, and nitrous oxide.

Gross Farm Income

Income which farm operators realize from farming. It includes cash receipts from the sale of farm products, government payments, value of food and fuels produced and consumed on farms, and the rental value of farm dwellings.

Gross primary productivity

The rate at which an ecosystem's producers capture and store a given amount of chemical energy as biomass in a given length of time.

Ground Water

Water beneath the earth's surface between saturated soil and rock, which supplies wells and springs


A place or type of site where an organism or population or community naturally occurs.

Habitat degradation

The diminishment of habitat quality, which results in a reduced ability to support flora and fauna species. Human activities leading to habitat degradation include polluting activities and the introduction of invasive species.

Habitat degradation

The diminishment of habitat quality, which results in a reduced ability to support flora and fauna species. Human activities leading to habitat degradation include polluting activities and the introduction of invasive species.

Habitat fragmentation

Fragmentation of habitats occur when a continuous has become divided into separate, often isolated small patches interspersed with other habitats. Habitat fragmentation stems from geological processes that slowly alter the lay out of the physical environment or human activities such as land clearing, housing, urban development and construction of roads or other infrastructure. Fragmentation of habitats is expected to lead to losses of species diversity in the longer term.

Habitat loss

The outcome of a process of land use change in which a ‘natural’; habitat-type is removed and replaced by another habitat-type, such as converting natural areas to production sites. In such process, flora and fauna species that previously used the site are displaced or destroyed. Generally this results in a reduction of biodiversity.

Happy Seeder

This technology combines stubbles, mulching and seed drilling functions in one machine. Apart from benefits like proper mulching of paddy residue instead of burning, timely sowing, reducing runoff, soil erosion, lesser deep percolation and improving soil health by incorporating plant nutrients



Whole forage plants which are cut and dried for animal feed.



Forage ensiled at relatively low moisture content (usually 40 to 50 %).

Hazardous waste

Waste that poses a risk to human health or the environment and needs to be handled and disposed of carefully. Examples include oil-based paints, car batteries, weed killers, bleach and waste electrical and electronic devices.


The hemolymph-filled space or body cavity of some invertebrates.


The oxygen-carrying pigment in red blood cells.


The fluid that is circulated through the body of an animal with an open circulatory system.


A trait in which the blood lacks a protein that is essential for clotting.


Portal circulation the system of blood movement through the digestive tract and liver.


A flowering, vascular seed plant that lacks a woody stem; a plant part used to add flavor to food.

Herbaceous Plant

An annual plant that is nonwoody.


Any agent used to control weeds and unwanted plants


A consumer that eats primary producers.


Macroorganisms that eat plants. Includes insect and beetle larva, grub, mouse, slug, snail, termite, woodchuck.


The transmission of traits from parents to their offspring.


Literally, "eats others." An organism that must consume other organisms to fuel its metabolism. Animals, including humans, are heterotrophs. Heterotrophic, adj.


The colon and rectum of some invertebrates.


Joint allows movement back and forth like a hinged door, as in the elbow.


A kind of cytokine that causes an inflammatory response to an injury resulting in redness, swelling, warmth, and pain.


A protein molecule that DNA wraps around during chromosome formation.


The part of an algal thallus that anchors it to a substrate.


A specific DNA sequence within a homeotic gene that regulates patterns of development.


The stable internal conditions of a living thing.

Homeotic Gene

A gene that controls the development of a specific adult structure.


A subgroup of primates that includes modern humans and their bipedal ancestors.


Features similar features that originated in a shared ancestor.

Homologous Chromosome

One of a pair of morphologically similar chromosomes.


A phenomenon in which all spores look alike and produce similar gametophytes.


Referring to a gene pair in which the two alleles code for the same trait.


A parasitic roundworm that feeds on its host’s blood by cutting into the intestinal wall.


A chemical secreted by an endocrine gland that specifically influences the activity of distant cells.


The branch of agricultural science which deals with production , utilization and improvement of fruits, vegetables, flowers or ornamental plants


An area on earth with an unusual concentration of species, many of which are often endemic to the area.

Human chorionic gonadotropin

A hormone secreted by the placenta that stimulates the corpus luteum.

Human Genome Project

Worldwide scientific collaboration to determine the nucleotide sequence of the entire human genome.

Human immunodeficiency virus

The virus that causes AIDS.

Humoral immune response

An arm of the immune response that involves mainly B cells and antibodies.

Huntington’s disease

A human genetic disorder caused by a dominant allele resulting in involuntary movements, mental deterioration, and eventual death.

Hydrogen Bond

A weak chemical bond between the hydrogen atom in one molecule and a negatively-charged region of another molecule.

Hydrologic cycle

Biogeochemical cycle that collects, purifies, and distributes the earth's fixed supply of water, from the environment to living organisms and then back to the environment.


The splitting of a molecule through reaction with water.


Referring to the molecular attraction to water.


Referring to the molecular repulsion of water.


The earth's liquid water (oceans, lakes other bodies of surface water, and underground water), the earth's frozen water (polar ice caps, floating ice caps, and ice in soil known as permafrost), and small amounts of water vapor in the atmosphere.


High blood pressure


Overproduction of thyroid hormones.


Describing a solution whose solute concentration is higher than that inside a cell.


The vegetative filament of a fungus.


A stemlike area in plants between the cotyledons and radicle


Overproduction of insulin.


A statement that can be tested experimentally.


Thyroid hormone deficiency.


Describing a solution whose solute concentration is lower than that inside a cell.


A polyhedron or a capsid of a virus with 20 triangular faces.


The middle portion of the small intestine.


The movement of individuals into a population.

Immune Response

A reaction of the body against a foreign substance.


Resistance to a specific pathogen.


The process by which the newly fertilized egg in the blastocyst stage imbeds itself into the lining of the uterus.

Important Bird Area (IBA)

Sites of importance to birds, identified by Birdlife International and International Waterfowl and Wetlands Research Bureau. The sites are identified for four groups of birds: regularly occurring migratory species which concentrate at and are dependent on particular sites either when breeding, or migration, or during the winter; globally threatened species (i.e species at risk of total extinction); species and sub-species threatened throughout all or parts of their range but not globally; species that have relatively small total world ranges with important populations in specific areas.

Inactivated Vaccine

A vaccine that has been treated so that its component microorganisms no longer have the ability to cause disease.


Mating with relatives.


Mating of close relatives resulting in increased genetic uniformity in the offspring.


A chisel-like tooth used for biting and cutting.

Incomplete Dominance

An inheritance relationship that occurs when both alleles influence the phenotype.

Incurrent Siphon

A tube through which water enters the mantle cavity of a bivalve.

independent assortment

During meiosis, the random distribution of genes from different chromosomes to the gametes.

Independent Variable

An experimentally manipulated variable.

Indeterminate Cleavage

A pattern of development in which the functional destiny of each cell is not determined early in the development of the embryo.

Indicator species

A species whose status provides information on the overall condition of the ecosystem and of other species in that ecosystem.

Indoleacetic Acid

An auxin produced in actively growing regions of plants.


In the lac operon, the molecule that binds to repressor molecules and induces gene expression.

Infectious Disease

A disease caused by a pathogen that can be transmitted from one individual to another.

Inferior Vena Cava

The large vein carrying blood from the lower part of the body.


The features of an organism are determined by a set of chromosomes.  These originate in the parents and are passed on to an offspring during fertilization. It follows then that since chromosomes are inherited, all the features of an organism must be inherited.


Dominant microorganisms which may be added to a compost pile. Generally, these are not necessary as there are microorganisms living on all organic matter, so your pile already has these in it.


A chemical substance used to kill insects.


Maintenance or study of organisms within an organism's native environment.

In-situ conservationThe conservation of biodiversity within the evolutionary dynamic ecosystems of the original habitat or natural environment.


The process of taking air into the lungs.


A hormone that lowers the blood glucose level.

Integrated pest management (IPM)

Combined use of biological, chemical, and cultivation methods in proper sequence and timing to keep the size of a pest population below the size that causes economically unacceptable loss of a crop or livestock animal.

Integrated Pest Management (IPM)

Using the best features of chemical, biological and cultural controls to reduce reliance on synthetic pesticides. It may include use of natural predators, chemical agents and crop rotations

Intellectual Property Rights (IPR)

Rights enabling an inventor to exclude imitators from the market for a certain period of time.

Intensive agriculture

A system of maximum output of agricultural land through use of chemicals and machinery


System of growing two or more crops on the same peace of land in rows simultaneously


Process of loosening the soil in between the crops’ rows using bullocks drawn or tractor drawn implements.

Intraspecific competition

Two or individual organisms of a single species trying to use the same limited resources in an ecosystem.

Intrinsic value

The value of creatures and plants independent of human recognition and estimation of their worth.

Invasive species

Invasive species are those that are introduced-intentionally or unintentionally-to an ecosystem in which they do not naturally appear and which threaten habitats, ecosystems, or native species. These species become invasive due to their high reproduction rates and by competing with and displacing native species, that naturally appear in that ecosystem.


On-site collection of data on natural resources and their properties.

Island biogeography

The study of the relationship between island area and species number. This idea has also been applied to isolated areas of habitat in continental areas which are effectively islands for many species. The extent to which habitat fragmentation may lead to extinction of species can be predicted from the relationship between number of species and island area.


A picture of an individual’s chromosomes.


A protein that forms hair, bird feathers, human fingernails, and the horny scales of reptiles.

Keystone species

A species whose loss from an ecosystem would cause a greater than average change in other species populations or ecosystem processes.


An excretory organ in which wastes are filtered from the blood.


In taxonomy, a group of similar phyla or divisions.

Kyoto Protocol, Kyoto agreement

An international agreement signed in Japan in 1997, attached to the UN Framework Convention on Climate Change. Under the agreement, which has been in force in Ireland since 2005, industrialized countries promised to reduce their combined greenhouse gas emissions to at least 5 percent below 1990 levels over the period 2008-2012.  See also UN Framework Convention on Climate Change


An insect mouthpart that functions like a lower lip.


The muscular contractions of the uterus and other events that lead to birth.


An insect mouthpart that functions like an upper lip.


A tiny lymph vessel.

lactic acid fermentation

The process by which pyruvic acid is converted to lactic acid.


A type of polysaccharide with glucose units linked differently from those in starch.

Large intestine

An organ of digestion in which water is reabsorbed.


An immature form of an organism that is morphologically distinct from that of an adult.


The voice box that houses the vocal cords.

Lateral Line System

A row of sensory structures that run the length of the body of a fish.

Lateral meristem in plants

A growing region that increases the diameter of roots and stems.


The process of causing roots to form on a stem.


one of the divisions of a blade.


one of the divisions of a blade.


The process of removal of soluble materials by the passage of water through soil


A family of plants that includes valuable food and forage species such as peas, beans, soybeans, peanuts, clovers, alfalfas, and sweet clover. Legumes convert nitrogen from the air to nitrates in the soil through a process known as nitrogen fixation. Many of these species are used as cover crops and are plowed under for soil improvement.















any plant of the family Leguminosae, such as a bean, a pea, or a lentil


a convex crystalline structure in the eye that focuses light on the retina


a convex crystalline structure in the eye that focuses light on the retina


a progressive, malignant disease of the blood-forming organs


a progressive, malignant disease of the blood-forming organs


a white blood cell


a white blood cell

lichena symbiotic association between fungi and green algae


A symbiotic association between fungi and green algae.

life expectancy

how long, on average, an individual is expected to live


a connective tissue in a joint


A connective tissue in a joint.

light reactions

The initial reactions in photosynthesis, including the absorption of light by photosystems I and II, the passage of electrons along the electron transport chains, the production of NADPH and O2, and the synthesis of ATP through chemiosmosis.

light reactions

the initial reactions in photosynthesis, including the absorption of light by photosystems I and II, the passage of electrons along the electron transport chains, the production of NADPH and O2, and the synthesis of ATP through chemiosmosis

limbic system

a group of clusters of neurons in the brain that helps regulate the emotions

limbic system

A group of clusters of neurons in the brain that helps regulate the emotions.

Limiting factor

biotic or abiotic factor that restrains the growth of a population

limiting factor

biotic or abiotic factor that restrains the growth of a population

linkage group

the group of genes, located on the same chromosome, that are usually inherited together


a kind of organic compound that is insoluble in water, such as fats and steroids


A kind of organic compound that is insoluble in water, such as fats and steroids.


Low-Input Sustainable Agriculture (LISA) is an alternative method of agriculture that reduces the application of purchased inputs such as fertilizer, pesticides, and herbicides. Methods include crop rotation, mechanical cultivation to control weeds, integrated pest management strategies, application of livestock manures, municipal sludge, and compost for fertilizer and over seeding of legumes into maturing fields of grain crops


organ that performs vital metabolic processes including filtration of blood, secretion of bile, and conversion of sugars into glycogen

Living collections

A management system involving the use of off-site methods such as zoological parks, botanic gardens, arboretums, and captive breeding programs to protect and maintain biological diversity in plants, animals, and microorganisms.

logistic growth

a model of population growth in which birth and death rates vary with population size and are equal at the carrying capacity

long-day plant

a plant that flowers when exposed to day lengths longer than the plant’s critical length

loop of Henle

in the kidney, the part of the nephron that maintains a high concentration of sodium chloride in the surrounding fluid


the respiratory organ where gas exchange occurs

luteal phase

the menstrual stage in which the corpus luteum develops

luteinizing hormone (LH)

a hormone that stimulates ovulation and androgen secretion by the corpus luteum


the fluid of the lymphatic system

lymphatic system

a series of one-way vessels that carry intercellular fluid from tissues to the bloodstream


a type of white blood cell occurring in two primary forms, T cells and B cells


a tumor in the tissues that form blood cells


the disintegration of a cell by disruption of the plasma membrane

lytic cycle

the replication process of viruses that results in the destruction of the host cell


a very large organic molecule composed of many smaller molecules


in Paramecia, the larger of the two types of nuclei


an element used by plant cells in relatively large amounts


Nutrients that plants require in substantial doses. They include nitrogen, phosphorus, potassium, calcium, sulfur and magnesium.



 Living organisms in the soil which are large enough to be seen with the naked eye. Includes mite, millipede centipede, snail, slug, spider, ant, beetle, cut worm, earthworm, rodent. (see herbivores, detritivores, and carnivores)



Living organisms in the soil which are large enough to be seen with the naked eye. Includes mite, millipede centipede, snail, slug, spider, ant, beetle, cut worm, earthworm, rodent. (see herbivores, detritivores, and carnivores)


a large white blood cell that engulfs pathogens and cellular debris


a sievelike plate on the aboral surface of an echinoderm through which water enters the water-vascular system

mammary gland

one of the milk-secreting glands of mammals


a movable mouthpart that usually functions in chewing


Mangroves are woody trees or shrubs that grow in coastal habitats in Water logged saline soils. Mangrove plants occupy shallow water and inter tidal zones in tropical and subtropical coastal regions.



the epidermal layer of mollusks

mantle cavity

a space between the mantle and the visceral mass in mollusks


Wetland without trees; in North America, this type of land is characterized by cattails

 and rushes.


a mammal that carries its young in a pouch


a fundamental property of an object generally regarded as equivalent to the amount of matter in the object.

mass extinction

one of the brief periods of time during which large numbers of species disappeared.

Megadiversity countries

The small number of countries, located largely in the tropics, which account for a high percentage of the world's biodiversity by virtue of containing very large numbers of species.

Mesophyllic bacteria

This group of bacteria species work to break down organic matter under "warm" conditions of 40 degrees up to 110 degrees. The ideal temperature of their environment is 70 to 90 degrees.

Mesophyllic bacteria

 This group of bacteria species work to break down organic matter under "warm" conditions of 40 degrees up to 110 degrees. The ideal temperature of their environment is 70 to 90 degrees.

Methane gas

 Explosive (when highly concentrated) gas that is formed when organic materials decompose in anaerobic conditions which exist in landfills. Landfill operators must have a method of venting methane gas before it becomes volatile.


Micro irrigation

Micro irrigation is the frequent application of small quantities on, above or below the soil surface, by surface drip, subsurface drip, micro sprayers or micro sprinklers. Water is applied as discrete or continuous drop, tiny streams or miniature sprays through emitters or application placed along a water delivery line near the plant. Micro irrigation is characterized by low flow rate , long duration irrigation, frequent irrigation, water applied near or into the root zone of plants and low pressure delivery systems.


Used interchangeably with "microorganism". (see microorganism)



In practice, a diverse classification of all those organisms not classed as plants or animals, usually minute microscopic or submicroscopic and found in nearly all environments. Examples are bacteria, cyanobacteria (blue-green algae), mycoplasma, protozoa, fungi (including yeasts), and viruses.

Minimum Viable Population (MVP)

The smallest isolated population having a good chance of surviving for a given number of years despite the foreseeable effects of demographic, environmental, and genetic events and natural catastrophes.

Mixed cropping

Growing two or more crops on the same piece of land simultaneously without maintaining row specification

Mixed farming

System of simultaneously pursuing agriculture, animal husbandry, poultry, apiculture, sericulture integrating term in such a manner that their natural interdependence is beneficially used


An agriculture practice in which a single species of plant is cultivated in an area. It requires large amounts of fertilizers and pesticides


Leaves, straw or compost used to cover growing plants to protect them from the wind or cold.

Multiple cropping

Growing two or more crops consecutively on the same field in the same year.

Municipal Waste

Waste produced in urban areas, mainly made up of household waste but also some small commercial waste that is similar to household waste


One category of symbiosis in which both participating species generally benefit.


National Ambient Air Quality Standard; federal standards specifying the maximum allowable levels (averaged over specific time periods) for regulated pollutants in ambient (outdoor) air


A plant or animal indigenous to a particular locality.

Native species

Flora and fauna species that occur naturally in a given area or region. Also referred to as indigenous species.

Natural environment

The natural environment comprises all living and non-living things that occur naturally on Earth. In its purest sense, it is thus an environment that is not the result of human activity or intervention. The natural environment may be contrasted to “the built environment”, and is also in contrast to the concept of cultural landscape.

Natural resources

Nutrients and minerals in the soil and deeper layers of the earth's crust; water; wild and domestic plants and animals; air; and other resources produced by the earth's natural processes.

Natural selection

One of several gradual mechanisms through which evolution occurs. Process by which a particular beneficial gene (or set of genes) is reproduced more than other genes in succeeding generations due to selective pressures in the environment that favor the beneficial gene. The result of natural selection is a population that contains a greater proportion of organisms better adapted to certain environmental conditions.


Microscopic soil worm, which may attack roots or other structures of plants and cause extensive damage

Net area sown

It is the net area sown under crops, the area sown more than once during the year being counted once only

Net farm income

The money and non-money income form operators realize from farming as a return for labor, investment, and management after production expenses have been paid. Net farm income is measure in two ways net farm income before inventory adjustment and net farm income after inventory adjustment. Net farm income doesn't include changes in the value of inventories such as crops and livestock at the end of the year


A chemical element essential to life and a primary plant nutrient. Animals get nitrogen from protein feeds; plants get it from soil; and some bacteria get it directly from air

Nitrogen cycle

Cyclic movement of nitrogen in different chemical forms from the environment to organisms and then back to the environment.

Nitrogen draft

 Incorporating high-carbon matter like wood chips into the soil (i.e., mixed into soil, not placed on top) can cause deficiencies in the nitrogen available to plant roots. Organic matter composts and, in order to compost, the high-carbon material requires the nitrogen from the soil to create the desired diet for microbial action.
N-p-k N-p-k is an abbreviation for nitrogen (n), phosphorus (p), and potassium (k). In the chemical philosophy, these three elements are considered important to force crop production (as opposed to the organic philosophy goal of improving the biodiversity of the soil). U.s. law requires that the ratio of these three elements be specified on every bag of commercially-available fertilizer. A ratio of 3-1-2 or 4-1-2 is considered good.

Nitrogen fixation

A process whereby nitrogen fixing bacteria living in mutualistic associations with plants convert atmospheric nitrogen to nitrogen compounds that plants can utilize directly.

Noise pollution

Noises that disturb the environment and people’s ability to enjoy it, for example continually sounding house alarms, loud music, air conditioning or other electrical units and aircraft or motor engines


Not able to be consumed and/or broken down by biological organisms. Non-biodegradable substances include plastics, aluminum, and many chemicals used in industry and agriculture. Particularly dangerous are non-biodegradable chemicals that are also toxic and tend to accumulate in organisms.

Non-point Pollution

Pollutants that cannot be traced to a specific source, including storm water runoff from urban and agricultural areas

Nonrenewable resource

Resource that exists in a fixed amount (stock) in various places in the earth's crust and has the potential for renewal only by geological, physical, and chemical processes taking place over hundreds of millions to billions of years. Examples are copper, aluminum, coal, and oil. We classify these resources as exhaustible because we are extracting and using them at a much faster rate than they were formed.

Normal Farming Practices

The customary and generally accepted activities, practices and procedures that farmers consistently adopt, use, or engage in the production and preparation for market of crops, livestock, and livestock products and in the production and harvesting of agricultural, agronomic, horticultural, silviculture, aquacultural crops and commodities.

No-till Farming

See zero till.

Noxious gases

Poisonous gases that can harm people and the environment. Some gases have a strong smell, for example sulphur dioxide and methane, while others, such as carbon monoxide, do not have any smell at all.



A substance or recognized plant nutrient, element, or compound which is used or sold for its plant nutritive content. The term can include livestock and poultry manures, compost as fertilizer, commercially manufactured chemical fertilizers, sewage sludge or any combination thereof


Any food or element an organism must take in to live, grow, or reproduce. Plant: An essential element in a particular ion or molecule that can be absorbed and used by he plant. For example, carbon, hydrogen, nitrogen, and phosphorus are essential elements; carbon dioxide, water, nitrate, and phosphate are respective nutrients. Animal: Materials such as protein, vitamins, and minerals that are required for growth, maintenance, and repair of the body and also materials such as carbohydrates that is required for energy.


Propagation and preservation of plant, animal, and micro-organism species outside their natural habitat.

Oil seed crops

Primarily soybeans, peanuts, cottonseed, and flaxseed used for the production of oils for cooking, protein meals, and nonfood uses. Less common oil crops include sunflower, safflower, castor beans, and sesame.


Preservation of species in their natural environment.


Plants that are pollinated by physical or biological agents (e g, wind, insects) and without human intervention or control)

Optimum sustainable population

the number of animals which will result in the maximum productivity of the population or the species, keeping in mind the carrying capacity of the habitat and the health of the ecosystem.


In this guide, matter from living, or once-living, things.


Organic Agriculture

The practice of growing crops without use of chemical fertilizers and pesticides.

Organic food

Plants and animals that are grown or reared without the use of synthetic fertilisers, pesticides or hormones.



Any living thing, from bacteria and fungi through to insects, plants, animals and humans.


Orthodox seedsSeeds that are able to withstand the reductions in moisture and temperature necessary for long-term storage and remain viable.

Over exploitation

Over exploitation occurs when harvesting of specimens of flora and fauna species from the wild is out of balance with reproduction patterns and, as a consequence, species may become extinct.

Over fishing

Harvesting so many fish of a species (especially immature fish) that there is not enough breeding stock left to replenish the species, such that it is not profitable to harvest them, leading to commercial extinction .


Destruction of vegetation when too many grazing animals feed too long and exceed the carrying capacity of a rangeland area.

Ozone layer

The thin protective layer of gas 10 to 50km above the Earth that acts as a filter for ultraviolet (UV) radiation from the sun. High UV levels can lead to skin cancer and cataracts and affect the growth of plants


The study of ancient ecosystems. Paleoecologists use data from such sources as tree rings, geologic deposits, fossils (pollen is a particularly popular tool), and coral bores to reconstruct the climate and ecology or ancient ecosystems.

Particulate matter

Fine solid or liquid particles that pollute the air and are added to the atmosphere by natural and man-made processes at the Earth’s surface. Examples of particulate matter include dust, smoke, soot, pollen and soil particles.



Land that is used to, or has the potential, to produce food for grazing animals
casualty, retirement planning and all other insurances


A government grant of temporary monopoly rights on innovative processes or products.


A disease causing microorganism, bacterium or virus.


A causal agent of disease.


The downward movement of water through soil under the influence of gravity


A plant that lives for more than two years


A pesticide is any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest. Pests can be insects, mice and other animals, unwanted plants (weeds), fungi, or microorganisms like bacteria and viruses. Though often misunderstood to refer only to insecticides, the term pesticide also applies to herbicides, weedicides, fungicides, and various other substances used to control pests (USEPA, 1997).

Pesticide Residue

A detectable level of a chemical residue in food product

Pesticide Tolerance Levels

Scientifically acceptable level of a pesticide residue that can exist on a fruit or vegetable product. Usually expressed in parts per million or billion.


A general term for any chemicals that are used to kill weeds, fungi, insects or other pests.



The observable appearance of an organism, as determined by environmental and genetic influences (in contrast to genotype).

Phosphorus cycle

Cyclic movement of phosphorus, in varying chemical forms, from the environment to organisms and then back to the environment.


The process plants use to change air and water into food, using the sun's energy.


Pertaining to the evolutionary history of a particular group of organisms.


In taxonomy, a high-level category just beneath the kingdom and above the class; a group of related, similar classes.


Chemicals found naturally in plants.

Pioneer species

First hardy, often xerophytic species (often microbes, mosses, and lichens) that begin colonizing a site as the first stage of ecological succession.


The transfer of pollen from an anther to a stigma of a flower of the same species.


An animal that carries pollen, such as insects, birds, or bats.


An alteration of the natural environment producing a condition that is harmful to living organisms


Trait a trait controlled by multiple genes.


A compound consisting of repeated linked monomers

Polymerase chain reaction (PCR)

Technique used to quickly make many copies of selected segments of DNA


A long chain of several amino acids


A segment of the brain stem


A group of individuals with common ancestry those are much more likely to breed with one another than with individuals from another such group.

Population and Habitat Viability Assessment (PHVA)

The theoretical modelling of minimum areas, habitat types and population sizes, to sustain any one or more species. Population size will be determined by the carrying capacity of the habitat.

Population change

An increase or decrease in the size of a population. It is equal to (births immigration) - (deaths emigration).

Population density

Number of organisms in a particular population found in a specified area.

Population dispersion

General pattern in which the members of a population are arranged throughout its habitat.

Population distribution

Variation of population density over a particular geographical area. For example, a country has a high population density in its urban areas and a much lower population density in rural areas.

Population Viability Analysis (PVA)

The theoretical determination of the minimum viable (in terms of genetic make-up) breeding population for any one species to survive in a given range.

Power-take-off (PTO)

A powered shaft, usually extending from the rear of the tractor and driven by the tractor motor, to supply rotative power to an attached or trailing implement such as a combine, hay baler, mower, etc.


An animal that obtains its food primarily by killing and consuming other animals.

Primary (or natural) forest

A forest largely undisturbed by human activities.

Primary producer

An organism, such as a plant or microbe, that makes its own food and forms the bottom-most tier in a trophic system. Primary producers are the basis of the food web in most ecosystems Primary producers are able to convert abiotic raw materials into biotic tissue, either by capturing the sun's energy through photosynthesis (plants) or by harnessing the energy in chemical bonds through chemosynthesis (some microbes).

Primary productivity

The transformation of chemical or solar energy to biomass. Most primary production occurs through photosynthesis, whereby green plants convert solar energy, carbon dioxide, and water to glucose and eventually to plant tissue. In addition, some bacteria in the deep sea can convert chemical energy to biomass through chemosynthesis.

Protected Area (PA)

An area of land and/or sea especially dedicated to the protection and maintenance of biological diversity, and of natural and associated cultural resources, and managed through legal or other effective means.

Provinciality effect

Increased diversity of species because of geographical isolation.

Pyramid of biomass

Diagram representing the biomass (total dry weight of living organisms) that can be supported at each trophic level in a food web. The bottom of the pyramid is comprised of primary producers , while the peak of the pyramid is topped by one (or at most a small handful) apex predator . Humans are abnormal in that we cross all ecosystems and biomass pyramids, and in almost every one (excepting the polar caps and deepest of oceanic environments) we are the dominant apex predator.

Pyramid of energy flow

Also called a trophic pyramid . Diagram representing the flow of energy through each trophic level in a food chain or food web. With each energy transfer, only a small part (typically 10%) of the usable energy entering one trophic level is transferred to the organisms at the next trophic level, with the remaining 90% lost as heat or expended in metabolic processes.


A form of energy that is transmitted in waves, rays or particles from a natural source, such as the sun and the ground, or an artificial source, such as an x-ray machine. Radiation can be ionising or non-ionising. Ionising radiation includes ultraviolet rays, radon gas and X-rays. Too much exposure to ionising radiation can be harmful, leading to increased risk of cancer. Non-ionising radiation includes visible light, radio waves and microwaves. This type of radiation is less risky to health because it contains less energy, but it can still be harmful at high levels for a long time.



To break waste items down into their raw materials, which are then used to re-make the original item or make new items.



To break waste items down into their raw materials, which are then used to re-make the original item or make new items.


Red List

The IUCN Red List of Threatened Species provides taxonomic, conservation status and distribution information on taxa that have been globally evaluated using the IUCN Red List Categories and Criteria. This system is designed to determine the relative risk of extinction, and the main purpose of the IUCN Red List is to catalogue and highlight those taxa that are facing a higher risk of global extinction (i.e. those listed as Critically Endangered, Endangered and Vulnerable). The IUCN Red List also includes information on taxa that are categorized as Extinct or Extinct in the Wild; on taxa that cannot be evaluated because of insufficient information (i.e. are Data Deficient); and on taxa that are either close to meeting the threatened thresholds or that would be threatened were it not for an ongoing taxon-specific conservation programme (i.e. are Near Threatened).


The process of planting trees in forest lands to replace those that have been cut down.



The process of planting trees in forest lands to replace those that have been cut down.



Another name for waste.



Another name for waste.



The recovery of specific ecosystem services in a degraded ecosystem or habitat.

Renewable energy

Energy from renewable resources such as wind power, solar energy or biomass.


Renewable energy

Energy from renewable resources such as wind power, solar energy or biomass.


Renewable resource

A resource that can be used again and again without reducing its supply because it is constantly topped up, for example wind or sun rays.


Renewable resource

A resource that can be used again and again without reducing its supply because it is constantly topped up, for example wind or sun rays.


Resource economics

The study of natural ecosystem services and the economic values, in terms real-world currencies and capital valuations, of those services. One of the goals of resource economics is to assist policy makers in performing the cost-benefit analysis of various plans of action or inaction with regard to the natural world. The value of an ecosystem service is determined by calculating what it would cost to perform the same service artificially if the naturally-occurring service were disrupted or destroyed.


The return of an ecosystem or habitat to its original community structure, natural complement of species, and natural functions.


The return of an ecosystem or habitat to its original community structure, natural complement of species, and natural functions.


To use an item more than once for the same purpose, which helps save money, time, energy and resources.



To use an item more than once for the same purpose, which helps save money, time, energy and resources.



Riparian describes the land immediate surrounding water sources where water strongly influences the immediate ecosystem.


Riparian describes the land immediate surrounding water sources where water strongly influences the immediate ecosystem. (Shyam, R., 2008)

Row crops

The rows or planting beds are far enough apart to permit the operation of machinery between them for cultural operations.


Organisms that thrive on dead organism as its source of nutrition.


Soils or other surface materials transported by surface water as a product of erosion.

Seed bank

A facility designed for the ex situ conservation of individual plant varieties through seed preservation and storage.


Natural selection is the differential contribution of offspring to the next generation by various genetic types belonging to the same populations. Artificial selection is the intentional manipulation by man of the fitness of individuals in a population to produce a desired evolutionary response.


Liquid wastes from communities, which may be a mixture of domestic effluent from homes and liquid waste from industry.

Shifting Cultivation

Shifting cultivation also known as “Jhuming” was practiced by nomadic people in the past and is still in vogue in some hilly regions of North East India. Shifting cultivation has caused substantial loss of biodiversity. People in the hilly terrains clear the forest by fire and sow the seed in the cleared land. As the crops mature, they harvest it and then move to a new location. After a long time they come back again to the first location for growing crop in a cyclic order and this is called a “Jhum cycle”. In past one Jhum cycle used to complete in 25 to 50 years. But now it is complete in just 5 to 8 years due to heavy population pressure and shrinkage in agricultural land. 


Animal feed resulting from the storage and fermentation of green or wet crops (grass, legumes, field corn, etc) under anaerobic condition.


Air pollution consisting of smoke and fog, which occurs in large urban and industrial areas and is mainly caused by the action of sunlight on burned fuels, mostly from car exhausts. Smog can cause eye irritations and breathing problems and damage plant life.


Solar panel

A panel fixed to the roof of a building that uses special cells to collect energy from the sun and convert it to electricity to heat the building and/or power the lights, appliances or equipment.


Specialist species

Species with a narrow ecological niche. They may be able to live in only one type of habitat, tolerate only a narrow range of climatic or other environmental conditions, or they may use only one or a few types of food.


Formation of two species from one species as a result of divergent natural selection in response to changes in environmental conditions; usually takes thousands or tens of thousands of years.


A group of organisms capable of interbreeding freely with each other but not with members of other species.

Species diversity

The number and variety of species found in a given area in a region.

Species richness

The number of species within a specified region or locality.

Sprinkler irrigation

System of irrigation, wherein the water is pumped into metal pipes and is forced to come out of rotating nozzles so that the water reaches the soil almost similar to rain for a specified distance around nozzle


A recognizable area of plants that is relatively homogeneous and can be managed as a single unit


A distinct form or race of a species.


The more or less predictable changes in the composition of communities following a natural or human disturbance.


Ability of a system to survive for some specified (finite) time.

Sustainable agriculture

Method of growing crops and raising livestock based on organic fertilizers, soil conservation, water conservation, biological control of pests, and minimal use of non-renewable fossil-fuel energy.

Sustainable Agriculture

Agriculture practices that ensure long term productivity with minimum harmful effects, enhance environmental quality, make the most efficient use of resources, sustain the economic viability of farm operations and enhance the quality of life

Sustainable development

Development that meets the needs and aspirations of the current generation without compromising the ability to meet those of future generations.

Sustainable development

Development using land or energy sources in a way that meets the needs of people today without reducing the ability of future generations to meet their own needs.


Sustainable living

Taking no more potentially renewable resources from the natural world than can be replenished naturally and not overloading the capacity of the environment to cleanse and renew itself by natural processes.

Sustainable system

A system that survives and functions over some specified (finite) time; a system that attains its full expected lifetime.

Sustainable use

The use of components of biological diversity in a way and at a rate that does not lead to the long-term decline of biological diversity, thereby maintaining its potential to meet the needs and aspirations of present and future generations.

Sustainable yield (sustained yield)

Highest rate at which a potentially renewable resource can be used without reducing its available supply throughout the world or in a particular area.

Sychrophilic bacteria

This group of bacteria species work to break down organic matter under "cold" conditions of 0 degrees up to over 55 degrees. They generate low levels of heat.


Refers to a component or member of a system of symbiosis. "These organisms have a symbiotic relationship."

Taxon (pl. taxa)

The named classification unit (eg Homo sapiens, Hominidae, or Mammalia) to which individuals, or sets of species, are assigned. Higher taxa are those above the species level.


The classification of animals and plants based upon natural relationships.


A layer of organic matter that begins to grow between the base of a plant and the soil. Usually discussed as a problem with lawns as dead roots and stems accumulate. Proponents of the organic philosophy say that in an organic program where soil has achieved a healthy balance, microorganisms are present to feed on mulched grass clippings and prevent thatch. However, if long grass (generally meaning growth of more than a week) is cut and mulched, there may be an excess of clippings which is too great for the existing population of microbes to handle in a timely way. Use your own judgement in determining how much is too much, then remove excess clippings from the yard and put them into the compost bin. Clippings of any length that are wet or matted should be removed from the lawn and placed in the compost bin.


Thermophilic bacteria

 This group of bacteria species work to break down organic matter under "hot" conditions of 104 degrees up to 170 degrees. This type of bacteria can perform the greatest decomposition in the shortest amount of time.


Thermophilic bacteria

This group of bacteria species work to break down organic matter under "hot" conditions of 104 degrees up to 170 degrees. This type of bacteria can perform the greatest decomposition in the shortest amount of time.


Organisms which function within a temperature range of 45°C to 80°C.

ThermopilicOrganisms which function within a temperature range of 45°C to 80°C.


Threatened species

Wild species that is still abundant in its natural range but is likely to become endangered within the foreseeable future because of a decline in numbers.


The use of mechanized means to loosen soil and improve growing conditions for crops


 Tilth is land which has been prepared for growing crops by plowing and fertilization. In discussions of composting and organic gardening, the phrase "the tilth of the soil" is often used to describe the general health of the soil including a balance of nutrients, water, and air.


Abbreviation for the texas natural resource conservation commission.


Top soil

The upper most layer of soil that contains large amount of organic matter.

Total Cropped Area

It includes total area covered with crops during the year. In case different crops are raised on the same land during the year, the same area is counted more than ones.


Poisonous or harmful to the body (ecotoxic relates to damage to the environment).


A poisonous substance that can either be natural (produced by plants, animals or bacteria) or manufactured. 


Traditional agriculture

The agriculture based on traditional practices such as crop rotation, use of animal manure instead of chemical fertilizers.

Transmissible disease

A disease that is caused by living organisms (such as bacteria, viruses, and parasitic worms) and that can spread from one person to another by air, water, food, body fluids (or in some cases by insects or other organisms).

Trophic level

Position in the food chain, determined by the number of energy-transfer steps to that level.


This is the technique used to aerate compost windrows. Carried out either by a front-end loader or by windrow turner, the material is lifted into the air and dropped back forming a new pile. This process also released trapped heat and moisture, and ensures complete mixture of the feedstock.

UN Framework Convention on Climate Change

An international treaty joined by 192 countries that has the goal of preventing ‘dangerous’ human interference with the climate system and sets general rules for tackling climate change. 


UNESCO World Heritage Site

A natural or man-made site that has outstanding universal value and meets at least one of 10 conditions decided by UNESCO, the United Nations Educational, Scientific and Cultural Organisation. Ireland has two World Heritage Sites: the pre-historic sites of Newgrange, Knowth and Dowth in Co. Meath and Skellig Michael, a religious settlement from the 7 th century off the coast of Co. Cork.


Urban heat island

Buildup of heat in the atmosphere above an urban area. This is produced by the large concentration of cars, buildings, factories, and other heat-producing activities.

vulnerable species

Naturally rare organisms or species whose numbers have been so reduced by human activities that they are susceptible to actions that could push them into threatened or endangered status.


Waste management

The management of waste collection, handling, processing, storage and transport from where it is produced to where it is finally disposed. See waste prevention.


Water holding capacity

Weight of water held by a given quantity of absolutely dry soil when saturated.

Water Table

The top layer of the zone of saturation; undulates according to the surface topography and subsurface structure.


Water saturation of soil that fills all air spaces and causes plant roots to die from lack of oxygen; a result of over irrigation.



An area of land that collects and discharges water into a single stream or other outlet. Also called a catchment or drainage basin.


 A wetland is a land area that is saturated with water, either permanently or seasonally, such that it takes on the characteristics of a distinct ecosystem.

Wild life

Un-domesticated and uncultivated life including both plant and animals in their natural habitat.

Wild relative

Plant species that are taxonomically related to crop species and serve as potential sources for genes in breeding of new varieties of those crops.

Wild species

Organisms captive or living in the wild that have not been subject to breeding to alter them from their native state.

Zero Emission

An engine, motor or other energy source that does not produce any gas or release any harmful gases directly into the environment.

Zero emissions

zero population growth (ZPG)The number of births at which people are just replacing themselves; also called the replacement level of fertility.


Zero tillage

Zero tillage (No-tillage) is a minimum tillage practice in which the crop is sown directly into soil not tilled since the harvest of the previous crop. Weed control is achieved by the use of herbicides and stubble is retained for erosion control. It is typically practiced in arable areas where fallowing is important.

zone of aerationUpper soil layers that hold both air and water.


zone of leaching

The layer of soil just beneath the topsoil where water percolates, removing soluble nutrients that accumulate in the subsoil.

zone of saturationLower soil layers where all spaces are filled with water.