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  Organizations     Dictionary     Red List of Threatened Species     Photoalbum  
 Dictionary :: biologist 
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Identical Twins

See monozygotic twins.

Idioblast

A distinct type of cell within a particular tissue.

Ileum

Part of the intestine that is found between the duodenum and the colon that hosts enzyme controlled actions breaking down foodstu.

Immigration

The movement of organisms to a specific area, perhaps, for example, an upstream aquatic environment to further downstream.

Immobilisation

The 'locking up' of inorganic compounds in biological organisms, effectively preventing them from continued circulation in the environment.

Immune Response

An immune system response due to the presence of a particular foreign antigen, such as bacteria, fungi or virus.

Immune System

A system that provides a defense mechanism to organism, providing defensive measures against antigens which would prove harmful to the organism.

Immunisation

The artificial administering of an antigen into an organism, usually killed or severely weakened so that the immune systems active and passive immunity.

Immunodeficiency

The inability of the immune system to provide a response to a pathogenic attack.

Immunoglobin

A type of protein of which there are five different variations. These Y shaped structures possessing antibody capabilities that are harnessed in light of pathogenic attack of an organism, and are initiated within a specific immune response.

Immunology

The dedicated study of the immune system and immune responses.

Immunotherapy

A type of medical treatment where antibodies are administered into the patient to fight off infections.

Imprinting

A form of learning critical to some species in early development where the actions or presence of others "imprints" behavioural traits of others, for instance, offspring. Geese at an early age look for a mother figure, basically anything that is alive and.

In Situ

Something that is in its original place.

In Vitro

Biological processes or reactions that would normally occur within an organism but are made to occur in an artificial environment, i.e. a laboratory. See In Vivo.

In Vivo

Occurring within a biological organism. See In Vitro.

Inborn Error of Metabolism

An inherited condition from parent to offspring where the lack of correct genetic sequences coding for particular enzymes results in a lack or absence of that enzyme, meaning certain biochemical pathways are not fully executed due to this missing component.

Inbreeding

The mating of organisms between relatives, which usually decreases heterozygosity in the gene pool and done by selective breeders to produce hybrids.

Inbreeding Depression

The decrease in heterozygosity of alleles in a gene pool due to continuous

Incipient Species

A group of a particular species that are about to become genetically isolated from the rest of the species, perhaps due a geographical barrier, though at this time can still reproduce with other groups of the species before their gene pools become too distinct.

Incisor

Teeth found in mammals, specialised for biting.

Incomplete Dominance

A form of dominance in alleles, where the dominant allele is not expressed in its phenotype. For example, when two true breedi.

Independent Assortment

The random arrangement of chromosomes during meiotic divisions, which increases the number of genetic variations possible in gametes.

Indicator Community

The association of particular species with their favoured environment, hence the presence of a particular species can indicate the conditions of the environment.

Indicator Species

A species which is a good indicator of the living conditions in a particular habitat. The peppermoth will express a black phenotype in a polluted atmosphere and a white phenotype in a clean air atmosphere. In this case, the peppermoth is a good indicator species for measuring pollution.

Indigenous

Native, naturally occurring without the interference of man.

Individual Variation

The genetic variation within a particular species.

Indolacetic Acid

See Indole%20Acetic%20Acid (IAA).

Indole Acetic Acid

A type of auxin that is involved in growth within the meristematic areas of a plant.

Induced Mutation

A mutation that is deliberately introduced via implantation.

Inducer

A molecule that inhibits the action of the repressor of an operon, preventing it from freely binding with the operator gene and disabling its function.

Industrial Melanism

For information on industrial melanism please reference the tutorial on genetics and evolution regarding natural selection and industrial melanism.

Inert

Lacking any activity.

Infection

The invasion of an organism by parasitic microorganisms.

Infertile

The inability to produce offspring.

Infraspecific

Pertaining to within a species.

Infrasubspecific

Pertaining to within a subspecies.

Infundibulum

A growth of the pituitary gland found in the posterior region of the brain.

Ingestion

The entering of foodstuff into the gut where it can be digested.

Inhale

The action involving the intake of gases via breathing.

Inheritance

The genetic material that is passed on from parents to offspring, therefore pre-determining the phenotype of the offspring (before any other factor like mutations take effect).

Inherited Abnormality

A pre-determined consequence deriving from the genotype of the organisms parents. These can be caused by mutations in complete chromosomes or relatively smaller changes at the gene level. Non-Disjunction is a chromosomal defect while phenylketonuria is a genetic defect.

Inhibiting Factor

A factor that inhibits the secretion of hormones, as opposed to a releasing factor.

Inhibition

A situation where enzymes are unable to execute their function.

Initial

Either one or many cells that are differentiating to become specialised to a particular function, e.g. a white blood cell.

Initiation Codon

A codon that is responsible for activating the translation of DNA to mRNA, usually with the sequence of AUG or GUG.

Innate Reflex

A reflex that is inherited and therefore not learned from the external environment.

Innervate (1)

Pertaining to the system providing nerves to a particular part of an organism.

Innervate (2)

To stimulate a nerve with electronic pulses.

Inoculaton

The appliance of biological material to an environment or organism.

Inoculum

A medium to which biological material is introduced, for instance a particular environment or an organism.

Inotropic

Pertaining to factors that influence the rate or force of heart contractions, that can either have a positive or negative effect on either.

Insecticide

Substances that are capable of killing insects, used by humans to those who are considered pests.

Insecticide Resistance

The ability of an insect to withstand the effects of an insecticide by becoming resistant to its toxic effects by means of natural selection and mutations.

Insectivore

Insect eating organisms.

Insemination

The occurrence where the sperm mother cell fuses with the mother egg cell in fertilisation.

Insertion Mutation

A type of mutation where part of a genetic sequence is added to a chromosome, causing a frameshift in the genetic information on that chromosome.

Insight Learning

A type of learning expressed in intelligent organisms where organisms are capable of using reasoned thought and past recollections to solve a problem by utilising their previously experienced concepts alongside their reasoning skills to come to a logical conclusion (and perhaps learn new things).Inspiration

Breathing in.

Instantaneous Speciation

Individuals that are isolated from their parents and capable of producing members of a new species from its altered genome.

Instinct

Inherited behavioural characteristics.

Instinctive Behaviour

Organisms expressing behavioural patterns that are genetically controlled as opposed to behaviour that has been previously learned in the organisms lifetime.

Insulin

A type of hormone that regulates sugar concentration in blood. Insulin is secreted by the Islets of Langerhans in the pancreas, where when active, promotes the conversion of glucose into its stored form, glycogen.

Integrated Control

The harnessing of biological and chemical properties to control 'pests' and pathogens in order to protect an environment, species or the well being of humans.

Integration

A term used to confirm the successful binding of foreign DNA into an organisms own genome.

A surface molecule found on the exterior of cells that helps bind whole cells together. It is also believed to be responsible for a role in cell signalling, which allows cells to 'communicate' for purposes such as gene expression.

Intelligence (IQ)

An ability in advanced organisms that can create and understand abstract ideas. Intelligence is measured in IQ (Intelligence Quotient).

Interbreed (Infraspecific)

The breeding of two organisms from two distinct races.

Interbreed (Intraspecific)

The breeding of two organisms of the same species and family.

Intercellular

Pertaining to the space between cells.

Intercostal Muscles

A set of muscles found under the ribs that have a role in the contraction and relaxing of the chest area in breathing.

Interfascicular Cambium

Meristematic tissue deriving from parenchyma that forms a complete ring of cambium round the plant by undergoing rapid cell division to produce an effect known as secondary thickening.

Interference Colours

Colours that travel at different velocities which are reflected by other surfaces which alters the appearance of actual colours to the eyes.

Interferon

A type of glycoprotein that is produced as a defense mechanism against pathogens.

Interkinesis

A resting point that occurs between two meiotic divisions.

Intermediate Host

An organism that hosts a parasite for part of the parasites life cycle.

Intermediate Neurone

See Interneurone.

Internal Clock

See Biological Clock.

Internal Environment

The environmental conditions of the medium in which the cells of an organism exist in.

Internal Respiration

Respiration that occurs within cells of an organism.

Interneurone

Nerve cells that transmit messages from afferent neurones to efferent neurones.

Internode

The portion of stem found between lateral meristems in plants.

Internunciary Neurone

See Interneurone.

Interoceptor

A type of receptor that deals with stimuli within the body.

Intersex

An organism that possesses characteristics somewhere between a male and a female.

Interspecific Competition

The competition for resources between species which is a form of environmental resistance to populations of a species. Compare to intraspecific competition.

Intestine

Part of the digestive system in between the stomach and the anus, where excess material from the system is excreted. The intestine is responsible for the digestion and re-absorption of materials into the blood while providing a passageway for the excess material to be excreted into the external environment via the anus.

Intraspecific

Within a species.

Intraspecific Competition

Competition for resources between members of the same species, compare to interspecific competition.

Introduced Species

A species that does not occur naturally in a given area, though has been introduced to it.

Inversion

A type of mutation where part of the genetic sequence of a chromosome is reversed.

Involuntary Muscle

A type of muscle that is not consciously controlled by an organism and reacts 'involuntarily' to nerve system signals.

Involuntary Response

Responses that are not controlled by the individual, for example when someone flashes something past your face your involuntary response may be to blink.

Ion

Atoms that possess a positive or negative charge due to the gain or loss of electrons.

Ion Pump

A protein responsible to the active transport of ions across a membrane.

Ionic Bonds

Bonds responsible for holding ions together.

Islets of Langerhans

Cells found in the pancreas that are responsible for secreting insulin and glucagon.

Isoenzyme

Enzymes  that are essentially dissimilar but catalyse the same reaction.

Isolating Barrier

Geographical barriers that prevent gene flow, and ultimately prevent reproduction between organisms.

Isolating Mechanism

Any factor that actively prevents breeding between organisms.

Isotonic

Pertaining to concentrations of water substances where two bodies of the liquid contain the same water potential, where no osmosis will occur between the two bodies of water due to an equal concentration of water.

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