Biology I
What is ileum ?
The third and last section of the small intestine.
What is imaginal disk ?
A region or cluster of cells in the larvae of an insect that are undifferentiated and are determined to form specific organs or tissues during metamorphosis to the adult stage.
What is imaging ?
A medical diagnostic technique by which useful organ images are obtained from the radiation emitted by RADIONUCLIDEs that are introduced into organs, or from radiation absorbed by atomic nuclei within the organs. Typical examples are imaging obtained by recording the radiation emitted by a radionuclide such as 99mTc, and the 1H-NMR imaging obtained by whole-body NUCLEAR MAGNETIC RESONANCE measurements.
What is immigration ?
The moving into a location in which the individual is not a native of the area.
What is immune response ?
The process by which the body of an organism recognizes and fights invasion of microorganisms, viruses, and other substances (antigens) that may be harmful to the body; the total time from recognition of the intrusion to attack or tolerance of the antigen.
What is immunoglobulin (Ig) ?
Also known as antibodies, these are proteins created by plasma cells and B cells that are designed to control the body’s immune response by binding to antigens. There are more than 1,000 possible antibody variations and five major types, and each is specific to a particular antigen. Of the five main types—IgA, IgD, IgE, IgG, and IgM—the most common are IgA, IgG, and IgM.
What is immunogold ?
A method for visualizing proteins in electron microscopy within a cell using gold particles attached to an AN
What is imperfect fungi ?
Fungi (deuteromycetes) that do not have sexually produced spores as part of their life cycle. They cause skin diseases in humans and include the organisms causing ringworm and athlete’s foot.
What is impotence (erectile dysfunction) ?
Refers to a man’s inability to achieve or maintain an erection suitable enough to complete sexual intercourse.
What is imprinting ?
A type of behavior learned during a certain critical time in development that promotes the learning of behavior and characteristics of the species and is difficult to reverse, regardless of circumstances. An example is the attachment behavior among birds to the mother during the first few hours after hatching. In genetics, it is when an allele at a particular locus is inactivated or altered depending on whether it was inherited by the mother or father.
What is inbreeding ?
The production of offspring by closely related parents with a high likelihood of carrying similar deleterious recessive mutations that may be expressed in the phenotypes of the offspring. The resulting populations may suffer a higher than average incidence of recessive genetic disorders.
What is incest ?
When two people too closely related have intercourse, i.e., a parent and child, or two first cousins. Usually socially prohibited.
What is incomplete dominance ?
A type of inheritance where the heterozygote that has two different alleles (one dominant, one recessive) of a gene pair has a different appearance (phenotype) compared with the homozygous (identical alleles for a given gene) parents.
What is incomplete flower ?
A flower lacking one of the four major parts: SEPALs, petals, STAMENs, or CARPELs.
What is incomplete metamorphosis ?
Part of a life cycle of an insect where the nymph stage, or immature form, resembles the adult after hatching and slowly changes into the adult form through a series of molts; does not have a pupa stage. Examples are grasshoppers (Othoptera), aphids, cicadas, and whiteflies. A form of incomplete metamorphosis called gradual metamorphosis is when there is no pupal stage and the nymphs look like the adults minus the wings. Unlike complete metamorphosis, which has four stages (EGG, LARVA, PUPA, and adult), incomplete metamorphosis only has three (no pupa).
What is indeterminate cleavage ?
A form of cleavage found in dueterostomes (e.g., chordates and echinoderms) where each cell produced during early cleavage division has the ability to develop into a complete embryo.
What is indeterminate egg layer ?
The ability to induce birds to lay more eggs by removing or destroying eggs they have already laid. Also called double clutching.
What is indeterminate growth ?
When an organism continues to grow throughout its life span (ontogeny); characteristic of plants.
What is indeterminate inflorescence ?
When the central part of the flower is the last to open. Terminal flowers open last and lower flowers open first.
What is index fossils ?
A biologic method of time correlation using commonly found fossils that are limited to a specific time span. For example, trilobites, though common in the Paleozoic, are not found before the Cambrian period. Some lineages of fossil organisms evolved rapidly, so that the vertical stratigraphic range of the species was short but the species was widespread. A dating technique to correlate the ages of rocks in difference locations (biostratigraphy).
What is indigenous ?
An organism that is native and not introduced in a specific environment with certain boundaries.
What is induced fit ?
The change in the shape of an enzyme’s active site to accommodate and bind firmly to the substrate that enters the site.
What is induction ?
The process whereby one set of embryonic cells influences the development of another set of embryonic cells.
What is industrial melanism ?
A natural selection process that developed in the 19th century, when certain species such as moths developed a coloration adaptation to compete with industrial soot pollution (e.g., the blackening of tree bark). England’s peppered moth (Biston betularia) is the often-used example.
What is inert ?
STABLE and unreactive under specified conditions.
What is infanticide ?
The purposeful killing of an infant or baby after birth or shortly after.
What is infectious ?
The ability to transmit a disease; an infectious disease caused by some microbe or agent that is infectious.
What is inferior ovary (epigynous ovary) ?
Having the calyx, corolla, and androecium appear to rise from the very top of the ovary.
What is inflammatory response ?
The reaction the body takes to invading microorganisms. The response includes: an increase in the blood flow to the infected area to increase the number of leukocytes that can fight the invader; the complementary thinning of the local blood capillary cell walls to allow the increased number of leukocytes to enter along with the leukocytes releasing cytokines, immune-signaling chemicals, to call more leukocytes to the area; and increase in temperature at the infected site.
What is inflorescence ?
Refers to the various positional and structural arrangements of a flower cluster on a floral axis. The two main categories are racemose (indefinite and not terminating in a flower) and cymose (definite,floral arrangements can be in the form of a panicle [slightly elongated with central axis with branches that branch themselves]. Examples of racemose inflorescence are: raceme (elongated with central axis composed of simple pedicels of about equal length); spike (elongated with central axis with sessile/subsessile flowers); corymb (flat topped with vertical axis with pedicels or branches of unequal length); or umbel (several branches from a common point of the peduncle).
What is ingestion ?
The process of obtaining nutrients by heterotrophic organisms by eating other organisms or other organic matter.
What is inhibition ?
The decrease in the rate of a reaction brought about by the addition of a substance (INHIBITOR).
What is inhibitor ?
A substance that decreases the rate of ENZYME catalysis or other chemical reaction.
What is inhibitory postsynaptic potential (IPSP) ?
A small electrical charge of a few millivolts, creating a local hyperpolarization (increase in membrane potential on the negativity of the inside of the neuron) in the membrane of a postsynaptic neuron. Caused when an inhibitory neurotransmitter from a presynaptic cell binds to a postsynaptic receptor, which makes it difficult for a postsynaptic neuron to generate an action potential.
What is innate behavior ?
Behavior that is performed without prior learning; considered hardwired in the nervous system. Usually a behavior that is inflexible and built in.
What is inner cell mass ?
After a sperm fertilizes an egg, the resulting single cell that is produced is referred to as totipotent, meaning that it has the potential to form an entire organism. Cell division begins immediately, and after a few days the cells begin to specialize, forming a blastocyst, a hollow sphere of cells. The blastocyst has an outer layer of cells, and inside the sphere is the inner cell mass, a cluster of cells that protrude into one end of the cavity and will develop into virtually all of the human tissues.
What is inositol 1,4,5 triphosphate (IP3) ?
Acts as a second messenger; increases intracellular calcium and activates calcineurin, an intermediate in the T cell activation pathway; binds to and activates a calcium channel in the endoplasmic reticulum. A second messenger functions as an intermediate between certain nonsteroid hormones and the third messenger, resulting in a rise in cytoplasmic Ca2+ concentration.
What is inquiline ?
Any organism that lives in the home of another and shares its food or home (e.g., scarab beetle, which lives in ant nests).
What is Insecta ?
The class of animals that contain more than 1 million named species and perhaps millions more that are not scientifically named as of yet. Found in almost every habitat worldwide, they are found in every shape and form, small and large. They all share a body composed of a head, thorax, and abdomen; a pair of relatively large compound eyes; usually three ocelli (simple eyes) and pair of antennae located on the head; mouthparts consisting of a labrum, a pair of mandibles and maxillae, a labium, and a tonguelike hypopharynx; two pairs of wings, derived from outgrowths of the body wall, and three pairs of walking legs.
What is insectivorous ?
Refers to an animal or plant that eats insects.
What is insertion ?
A mutation that occurs when one or more nucleotide pairs are added to a gene, causing a frame shift, which is a change in how the information in a gene is translated by the cell. Two other mutations include a deletion mutation, where one or more bases are removed from the DNA sequence of a gene, and substitution mutation, where one base is replaced by another at a single position in the DNA sequence of a gene.
What is insertion reaction ?
A chemical reaction or transformation of the general type X–Z + Y Ô X–Y–Z in which the connecting atom or group Y replaces the bond joining the parts X and Z of the reactant XZ.
What is insertion sequence ?
A short stretch of mobile bacterial DNA known as a transposon that has the capacity to move between different points within a genome, or change positions; special sequences at their terminal ends allow them to integrate into strands of DNA; usually are inverted repeats (two copies of the same or related sequence of DNA repeated in opposite orientation on the same molecule) at the ends of the insertion sequence; can alter gene expression; involved in transposition.
What is insight learning ?
Having the ability to perform the appropriate or correct behavior response in a first-time experience on the first try.
What is instinct ?
An organism’s innate, or inborn, intuitive ability to respond to a given stimulus in a fixed way.
What is insulin ?
A protein hormone produced in the pancreas by beta cells, located in the islets of Langerhans, that stimulates cellular utilization of glucose by body cells, by converting glucose and other carbohydrates to energy, and helps control blood-sugar levels by acting antagonistically with glucagons, the chief source of stored fuel, in the liver. It is released by various signals that are sensitive to the intake and digestion of food. It also acts as an important regulator of protein and lipid metabolism. Insulin is used as a drug to control insulin-dependent diabetes mellitus, a disorder that is caused by the insufficient production of insulin. Without insulin, cells do not absorb glucose. Diabetic individuals can have type I diabetes (juvenile) comprising about 10 percent of the population, or type II diabetes (adult). Presently some 16 million Americans have diabetes, with 1,700 new cases being diagnosed daily. Diabetes has been linked to the development of a variety of diseases including heart disease, stroke, peripheral vascular disease, and neurological disorders.
What is integral protein ?
A protein of biological membranes that penetrates into or spans the lipid bilayer of a cell membrane. The lipid bilayer is a protective membrane that surrounds the cell and consists of two layers of phospholipids.
What is inter ?
A prefix meaning between or among.
What is interbreed (crossbreed) ?
To breed with another kind or species; hybridize.
What is intercalation compounds ?
Compounds resulting from inclusion, usually without covalent bonding, of one kind of molecule (the guest molecule) in a matrix of another compound (the host compound), which has a layered structure. The host compound, with a rather rigid structure, may be macromolecular, crystalline, or amorphous.
What is interferon ?
A chemical messenger of the immune system, composed of a group of cytokine proteins that have antiviral characteristics that are capable of helping the immune response. Three main types of interferon—alpha, beta, and gamma—are produced by virus-infected cells and are released to coat uninfected cells, thus preventing them from becoming infected. Alpha interferon is produced by virus-infected monocytes and lymphocytes, while beta is produced by virusinfected fibroblasts. Gamma is produced by stimulated T and NK cells.
What is interleukin ?
A group of natural chemical glycoprotein messengers, acting as cytokines, that are secreted by different cells of the immune system to make other cells perform specific cellular functions. Interleukin-1 (IL-1) is released early by monocytes, macrophages, T cells, and other immune cells to fight infection. It stimulates T cell proliferation and protein synthesis and causes fever. Can be cleaved into a peptide involved in cell death (apoptosis). Interleukin-2 (IL-2) is produced by T helper and suppresser lymphocytes. IL-2 increases the expression of natural killer and other cytotoxic cells and stimulates helper T cells to proliferate more rapidly. IL-2 is produced commercially by recombinant DNA technology and used for the treatment of metastatic renal (i.e., kidney) cell cancer. Interleukin-4 (IL-4) is released by lymphocytes (TH-2 subset of T helper lymphocytes) and promotes antibody production by stimulating B cells to proliferate and mature and promotes allergic responses via production of the immunoglobulin IgE. Interleukin-6 (IL6) affects many different cells in the immune system by inducing differentiation and activation. Interleukin-10 (IL-10), like IL-4, is released by lymphocytes (the TH-2 subset of T helper lymphocytes). IL-10 enhances the humoral response and increases antibody production. Interleukin-12 (IL-12) induces the production of natural killer and other cytotoxic immune cells.
What is intermediate filament ?
A fibrous protein filament of the cytoskeleton that helps form ropelike bundles in animal cells and is about 10 nm in size, falling in the middle between the size of microtubules and microfilaments; provides tensile strength.
What is interneuron ?
One of the three types of neuron networks (along with sensory and motor neurons) that allow information flow by way of impulses and action potentials to travel through the nervous system. Found in the central nervous system, they provide the center of a loop that receives upstream input from thousands of motor neurons, then sends the signals to the brain, processes the returns, and then transmits the downstream output to a similar number of sensory neurons for action.
What is internode ?
The segment on a plant stem between the points where leaves are attached; the region or length of stem between two nodes.
What is interphase ?
One of the phases of cell division during the process of mitosis. Interphase is the stage between two successive cell divisions and the time when DNA is replicated in the nucleus, followed by mitosis. Interphase itself has several phases: the first gap phase (G1) is the time prior to DNA synthesis where the cell increases in mass; the synthesis or S phase is the time DNA is actually synthesized; and gap or G2 is the phase after DNA syntheses and cell protein synthesis and before the start of prophase.
What is interstitial ?
Refers to the space between cells, airways, blood vessels, alveoli, atoms, molecules, and even soil particles.
What is interstitial cells ?
Cells that exist in the connective tissues between other tissues and structures; cells among the seminiferous tubules, tiny tubes of the testis where sperm cells are produced and that secrete the male sex hormones testosterone and other androgens.
What is interstitial fluid (intercellular fluid) ?
Fluid that fills spaces between cells and provides pathways for the flow of nutrients, gases, and wastes between capillaries and cells.
What is intertidal zone ?
One of the oceanic zones where the ocean meets land; landform can be submerged or exposed; shallow shore area between low and high tide or water marks.
What is intrinsic activity ?
The maximal stimulatory response induced by a compound in relation to that of a given reference compound.
This term has evolved with common usage. It was introduced by E. J. Ariëns as a proportionality factor between tissue response and RECEPTOR occupancy. The numerical value of intrinsic activity (alpha) could range from unity (for full AGONISTs, i.e., agonist inducing the tissue maximal response) to zero (for ANTAGONISTs),the fractional values within this range denoting PARTIAL AGONISTs. Ariëns’s original definition equates the molecular nature of alpha to maximal response only when response is a linear function of receptor occupancy. This function has been verified. Thus, intrinsic activity, which is a DRUG and tissue parameter, cannot be used as a characteristic drug parameter for classification of drugs or drug receptors. For this purpose, a proportionality factor derived by null methods, namely, relative EFFICACY, should be used. Finally, “intrinsic activity” should not be used instead of “intrinsic efficacy.” A “partial agonist” should be termed “agonist with intermediate intrinsic efficacy” in a given tissue.
What is intrinsic rate of increase (rmax) ?
A mathematical parameter that measures the maximum rate at which a population will grow if resources are unlimited, using birth and death rates in a population as the determinants. It is the difference between the number of births and the number of deaths; the maximum population growth rate.
What is introgression ?
The movement of genes from one population into another through hybridization followed by backcrossing.
What is intron ?
An intervening section of DNA that occurs almost exclusively within a eukaryotic GENE, but which is not translated to amino acid SEQUENCEs in the gene product. The introns are removed from the premature mRNA through a process called splicing, which leaves the EXONs untouched, to form an active mRNA.
What is inverse agonist (negative antagonist) ?
A DRUG that acts at the same RECEPTOR as that of an AGONIST, yet produces an opposite effect.
What is inversion ?
A chromosomal aberration or mutation, occurring during meiosis or from mutagens, that involves detaching a chromosome segment, rotating it 180 degrees, and then reinserting it in its original location.
What is invertebrates ?
Animals that do not have a backbone or notochord. They are cold-blooded and have solid, external skeletons or hydrostatic skeletons. They include small protozoans, sponges, corals, tapeworms, spiders, mollusks, and others. Most animals on the planet (95 percent of all animal species) are invertebrates, and the majority of those, excepting insects, are aquatic.
What is in vitro fertilization ?
Fertilization outside the body, whereby a male sperm and female egg are combined in a laboratory. The embryo is then artificially transferred into a female’s uterus.
What is ion ?
An atom that acquires a charge by either gaining or losing an electron.
What is ion channel ?
Enables ions to flow rapidly through membranes in a thermodynamically downhill direction after an electrical or chemical impulse. Their structures usually consist of four to six membranespanning DOMAINs. This number determines the size of the pore and thus the size of the ion to be transported.
What is ionic bond ?
A chemical bond or link between two atoms due to an attraction between oppositely charged (positive-negative) ions.
What is ionophore ?
A compound that can carry specific ions through membranes of cells or organelles.
What is ion pump ?
Enables ions to flow through membranes in a thermodynamically uphill direction by the use of an energy source such as ATP or light. They consist of sugar-containing heteropeptide assemblies that open and close upon the binding and subsequent HYDROLYSIS of ATP, usually transporting more than one ion toward the outside or the inside of the membrane.
What is iron-responsive element ?
A specific base SEQUENCE in certain MESSENGER RNAs that code for various proteins of iron METABOLISM, which allows REGULATION at TRANSLATIONal level by the IRON-RESPONSIVE PROTEIN.
What is iron-responsive protein (IRP) ?
A protein that responds to the level of iron in the cell and regulates the biosynthesis of proteins of iron METABOLISM by binding to the IRON-RESPONSIVE ELEMENT on MESSENGER RNA.
What is iron-sulfur cluster ?
A unit comprising two or more iron atoms and bridging sulfide LIGANDs in an IRONSULFUR PROTEIN. The recommended designation of a CLUSTER consists of the iron and sulfide content, in square brackets, e.g., [2FE–2S], [4FE–4S]. The possible oxidation levels are indicated by the net charge excluding the ligands, for example a [4Fe–4S]2+ or [4Fe–4S]1+ or [4Fe–4S]2+; 1+ cluster.
What is iron-sulfur proteins ?
Proteins in which nonheme iron is coordinated with cysteine sulfur and usually also with inorganic sulfur. Divided into three major categories: RUBREDOXINs; simple iron-sulfur proteins, containing only IRON-SULFUR CLUSTERs; and complex iron-sulfur proteins, containing additional active redox centers such as FLAVIN, molybdenum, or HEME. In most iron-sulfur proteins the clusters function as electron transfer groups, but in others they have other functions such as catalysis of hydratase/dehydratase reactions, maintenance of protein structure, or REGULATION of activity.
What is irregular ?
Refers to flowers that are bilaterally symmetrical, i.e., that are divisible into equal halves only in one plane.
What is irruption ?
A rapid and temporary increase in population density, often followed by a mass emigration; common in bird species.
What is ischemia ?
Local deficiency of blood supply and dioxygen to an organ or tissue owing to constriction of the blood vessels or to an obstruction.
What is isobacteriochlorin ?
2,3,7,8-Tetrahydroporphyrin. A reduced PORPHYRIN with two pairs of con-fused saturated carbon atoms (C-2, C-3 and C-7, C-8) in two of the pyrrole rings.
What is isoenzymes ?
Multiple forms of ENZYMEs arising from genetically determined differences in PRIMARY STRUCTURE. The term does not apply to those derived by modification of the same primary SEQUENCE.
What is isogamy ?
Sexual reproduction involving the fusion of gametes that are similar in size or are morphologically indistinguishable, e.g., fungi such as zygomycetes.
What is isolating mechanism ?
Any environmental, behavioral, mechanical, or physiological barriers or characteristics that will prevent two individuals of different populations from producing viable progeny. Important for the development of new species.
What is isomerase ?
An ENZYME of EC class 5, which catalyzes the isomerization of a SUBSTRATE.
What is isomers ?
Compounds that have the same number and type of atoms (same molecular formula) but differ in the way they are combined with each other. They can differ by the bonding sequence, called structural or constitutional isomerism, or the way their atoms are arranged spatially, called stereoisomerism. Other types include conformational, configurational, geometric, optical, enantiomers, and diastereomers.
What is Isoptera ?
Termites, a social order of insects that are soft bodied and comprise about 2,300 species worldwide. They obtain their nutrition from eating wood and digesting cellulose with the help of bacteria and protozoans found in their intestinal area.
What is isosteres ?
Molecules or ions of similar size containing the same number of atoms and valence electrons, e.g., O2–, F–, Ne.
What is isotonic solutions ?
Solutions having identical osmotic pressures, i.e., a solution where cells do not swell or shrink.
What is isotope ?
A different form of a single element that has the same number of protons, but has a different number of neutrons in its nucleus. Radioactive isotopes are unstable and break down until they become stable. Carbon 14 is a radioactive isotope of carbon that is used to date fossilized organic matter.
What is isotropy ?
Lack of ANISOTROPY; the property of molecules and materials of having identical physical properties in all directions.
What is Ixodes ?
A genus of ticks. Ixodes scopularis is the vector for Lyme disease because it can carry a spirochete known as Borrelia burgdorferi that is transmitted upon the bite of the tick.
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