Biology Unit 3 Classification

Genetic Diversity

The greater the number of different alleles that all members of a species possess, the greater the genetic diversity of that species.

Allele frequency

The number of times an allele occurs within the gene pool in a population relative to all others at the same locus.

Gene pool

All the different alleles of all the genes of all the individuals in a population at any one time.

Natural Selection

Darwin's theory to explain the mechanism of evolution. The process by which organisms better adapted to their environment survive and reproduce and pass on their advantageous alleles to their offspring, whilst those less well adapted fail to do so.

Directional selection

Favours one extreme of the range of characteristics, and the other extreme is selected against - a shift in the population curve.

Stabilising selection

Favours the mean of the distribution because the extremes are at a selective disadvantage - the frequency of mean phenotype increases.

Polygenes

Group of genes that are responsible for controlling a characteristic.

Normal distribution curve

A bell-shaped curve is produced when a certain distribution is plotted on a graph.

Biodiversity

The range and variety of genes, species and habitats within a particular region. Made up of three components: genetic diversity, species diversity and ecosystem diversity.

Species

A group of organisms with a common ancestry and so share the same genes, capable of breeding together to produce fertile offspring, are reproductively separated from other species.

Binomial naming system

Linnaeus' system to name species. 1st: Generic name (genus). 2nd: Specific name (species) E.g. Felix tigris.

Hierarchy

Groups within larger groups, with no overlap between groups at each rank.

Artificial Classification

Process of classifying organisms based on differences useful at time e.g. colour, size, number of legs.

Phylogenetic Classification

Process of classifying organisms based upon evolutionary relationships between organisms and ancestors.

Analogous Characteristics

Characteristics with the same function, not the same evolutionary origins. e.g. wings of butterflies and birds used for flight but originated in different ways.

Homologous Characteristics

Characteristics with similar evolutionary origins regardless of their functions in the adult of a species, e.g. wing of a bird, arm of a human and front leg of a horse.

Taxon

Each group within a phylogenetic biological classification (pl. taxa).

Courtship behaviour

A specialised behaviour that precedes the fertilisation of eggs by a male to ensure successful reproduction.

Classification

The organisation of living organisms into groups.

Taxonomy

The practice of biological classification.

Domain

Largest taxon, either bacteria, archaea and eukarya.

Kingdom

Second largest taxon of classification. The Eukarya domain divides into Protoctista, Fungi, Plantae and Animalia.

Community

The organisms of all species that live in the same area.

Population

A group of organisms of the same species occupying a particular space at a particular time that can potentially interbreed.

Species diversity

Number of different species and number of individuals of each species within any one community.

Ecosystem Diversity

Range of different habitats within a particular area.

Genetic diversity

Variety of genes possessed by individuals that make up any one species.

Species richness

The number of different species represented in an ecological community. It does not take into account the abundance of species or their relative abundance distributions.

Index of diversity

A formula is used to quantify the biodiversity of a habitat. It takes into account the number of species present as well as the abundance of each species.

Biomass

The total mass of living material, normally measured in a specific area over a given period of time.

Conservation

Management of the Earth's natural resources in such a way that maximum use can be made of them in the future.

DNA sequencing

The process by which the base sequence of all or part of the genome of an organism.

DNA profiling

When non-coding areas of DNA are analysed to identify patterns.

Bioinformatics

Development of the software and computing tools needed to organise and analyse raw biological data.

Gel electrophoresis

The methods of separating fragments of proteins or nucleic acids based on their electrical charge and size.

Niche

Role of an organism within the habitat.

Anatomical adaptation

An adaptation involving the form of an organism.

Physiological adaptation

An adaptation involving the way the organisms works, including metabolic pathways.

Behavioural adaptation

An adaptation involving inherent behaviour making organisms better adapted for survival.

Selection pressure

The pressure exerted by a changed environment or niche on individuals in a population.

Resistant bacteria

A resistant bacteria is not affected by an antibiotic.

Speciation

Evolution of new species from existing ones. The process by which reproductive isolation occurs between two populations so that they evolve along their own separate paths into two separate species with different allele frequencies.

Allopatric speciation

Occurs when populations occupy different environments - they are geographically separated.

Sympatric speciation

Occurs when populations are reproductively isolated within the same environment.