IB Define terms

Diffusion is the passive movement of particles froma region of high concentration to a region of lowconcentration.

Osmosis is the passive movement of watermolecules, across a partially permeable membrane,from a region of lower solute concentration to aregion of higher solute concentration.

Denaturation is a structural change in a proteinthat results in the loss (usually permanent) of itsbiological properties.

Cell respiration is the controlled release of energyfrom organic compounds in cells to form ATP.

Gene: a heritable factor that controls a specificcharacteristic.

Allele: one specific form of a gene, differing fromother alleles by one or a few bases only andoccupying the same gene locus as other alleles ofthe gene.

Genome: the whole of the genetic information ofan organism.

Genotype: the alleles of an organism.

Phenotype: the characteristics of an organism.

Dominant allele: an allele that has the same effecton the phenotype whether it is present in thehomozygous or heterozygous state.

Recessive allele: an allele that only has an effect onthe phenotype when present in the homozygous state.

Codominant alleles: pairs of alleles that both affect the phenotype when present in a heterozygote

Locus: the particular position on homologous chromosomes of a gene.

Homozygous: having two identical alleles of a gene.

Heterozygous: having two different alleles of a gene.

Carrier: an individual that has one copy of arecessive allele that causes a genetic disease inindividuals that are homozygous for this allele.

Test cross: testing a suspected heterozygote bycrossing it with a known homozygous recessive.(The term backcross is no longer used.)

Clone: a group of genetically identical organisms ora group of cells derived from a single parent cell.

Species: a group of organisms that can interbreed and produce fertile offspring..

Habitat: the environment in which a speciesnormally lives or the location of a living organism.

Population: a group of organisms of the samespecies who live in the same area at the same time.

Community: a group of populations living and interacting with each other in an area.

Ecosystem: a community and its abioticenvironment.

Ecology: the study of relationships between living organisms and between organisms and their environment

Evolution is the cumulative change in the heritablecharacteristics of a population.

Pathogen: an organism or virus that causes adisease.

Transpiration is the loss of water vapour from theleaves and stems of plants.

Active immunity is immunity due to the productionof antibodies by the organism itself after the body’sdefence mechanisms have been stimulated by antigens.

Passive immunity is immunity due to the acquisitionof antibodies from another organism in which active immunity has been stimulated, including via theplacenta, colostrum, or by injection of antibodies

Excretion is the removal from the body of the wasteproducts of metabolic pathways.

Osmoregulation is the control of the water balanceof the blood, tissue or cytoplasm of a living organism.

Biomagnification is a process in which chemical substances become more concentrated at each trophic level.