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)

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

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.

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.