classification ib bio

Traditional hierarchy of taxa

The classification system that includes kingdom, phylum, class, order, family, genus, and species.

Cladogram

A diagram that represents evolutionary relationships among organisms, showing common ancestors and clades.

Clade

A group of organisms that have evolved from a common ancestor and share characteristics.

Conserved sequence

Identical or similar sequences of DNA across a species or a group of species.

Highly conserved sequence

Sequences that are identical or similar over long periods of evolution.

Molecular clock

A method of estimating the time since divergence between two clades based on the gradual accumulation of sequence differences.

Parsimony

A principle in biology that suggests the simplest explanation, requiring the least number of changes, is preferred in constructing cladograms.

Root (in a cladogram)

The starting point of a cladogram that represents the most recent common ancestor of all the organisms in the diagram.

Node (in a cladogram)

A point on a cladogram that represents a hypothetical common ancestor of the organisms branching from it.

Terminal branch (in a cladogram)

The endpoints of a cladogram that represent the current species or groups of species.

Evidence for clades

Base sequences of genes or amino acid sequences of proteins, as well as morphological traits.

Evolutionary relationships

Connections between species based on their common ancestry and divergence over time.

Biological sequence similarities

Similarities in nitrogenous base or amino acid sequences between species that indicate evolutionary relationships.

Reclassification of species

The process of changing the classification of species based on new evidence from molecular sequence data.

Three domains of life

The classification of all organisms into three groups: Bacteria, Archaea, and Eukarya.

rRNA base sequences

Sequences of ribosomal RNA that provide evidence for the reclassification of life forms.

Functional requirements for gene products

One hypothesis explaining conserved sequences, suggesting that certain sequences are maintained due to their essential functions.

Slower rates of mutation

Another hypothesis for conserved sequences, indicating that some genes mutate less frequently over time.

Time and evolutionary relationships

The relationship that suggests that the longer the time since divergence, the greater the differences in biological sequences.

Analysis of cladograms

The process of interpreting cladograms to deduce evolutionary relationships, common ancestry, and clades.

Case study of plant species transfer

An example used to illustrate the reclassification of species based on molecular sequence data, such as the figwort family.