IB Biology SL

Organic compound

A compound that contains carbon found in living organisms, excluding carbonates and oxides


Biological catalysts made of protein that speed up the rate of a reaction

Active site

The region of an enzyme where the substrate binds


A structural change in the 3-D shape of a protein causing the loss of its chemical properties

Cell respiration

The controlled release of enrgy from organic compiunds in cells to form ATP


A heritable factor that controls a specific characteristic


Specific forms of a gene, differing by one or few bases only and occupying the same locus of the gene


The whole of the genetic information of an organism

Gene mutation

A change in the gene sequence

Homologous chromosomes

Chromosomes similar in structure, with the same genes, but coming from different parents


The alleles of an organism


The characteristics lof an organism

Dominant allele

An allele that has the same effect on the phenotype in the homozygous of heterozygous state

Recessive allele

An allele that only affects the phenotype in the homozygous state

Codominant alleles

Pairs of alleles that both affect the phenotype when present in the heterozygous state


The position of a gene on homologous chromosmes


Having two identical alleles of a gene


Having two different alleles of a gene


An individual that has one copy of a recessive gene coding for a genetic disease (that appears in homozygous individuals)

Test cross

Testing a suspected heterozygote by crossing it with a known homozygous recessive

Sex linkage

Occurs when genes are present on the sex chomosomes (X or sometimes Y) and are thus inherited with gender


A group of genetically identical organisms or cells derived from a single parent


A group of organisms that can interbreed and produce fertile offpring


The environment in which a species normally lives/The location of living organisms


A group of organisms of the same species who live in the same area at the same time


A group of populations living and interacting with each other in an area


A community and its abiotic environment


The study of relationships between living organisms and their environment


An organism that synthesizes its organic molecules from simple inorganic substances


An organism that obtains organis molecules from other organisms


An organism that ingests other organic matter that is living or recently killed


An organism that ingests non-living organic matter


An orgainism that lives on/in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion

Trophic level

Level in a food chain defined by the method of obtaining food and in which all organisms are the same number of energy transfers away from the producer


The cumulative change in the heritable characteristics of a population


The products of digestions being absorbed from the digestive tract into the blood


The products of digestion are absorbed from the blood to the body cells


An organism or virus that causes a disease


Molecules recognised as foreign


Soluble proteins produced by the immunes system as a response to antigens


A pumping mechanism moving air in and out of the lungs efficiently, maintaining the concentration gradient for diffusion in the alveoli

Gas exchange

The exchange of gas of an organism with its surroundings

Resting potential

Potential difference across a nerve cell membrane when it is not being stimulated (repolarised) (-70mV)

Action potential

Potential difference produced across a nerve cell membrane when it is stimulated (depolarised) (+40mV)

Type I diabetes

Individual with no or little insulin produced

Type II diabetes

Individual with body cells less sensitive to insulin