Bio II Flash Cards

Taxonomy

The science of describing, naming, and classifying living and extinct organisms.

Systematics

The study of evolutionary relationships among organisms.

Taxon

A group or category used in biological classification.

Taxonomic hierarchy

The system of organizing organisms into successive levels from broad to specific.

Taxonomic hierarchy (broad → specific)

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species.

Highest taxonomic level

Domain.

Three domains

Bacteria, Archaea, and Eukarya.

Bacteria

One of the three domains; contains prokaryotic organisms.

Archaea

One of the three domains; contains prokaryotic organisms.

Eukarya

One of the three domains; contains eukaryotic organisms.

Prokaryotic cell

A cell that lacks a nucleus and membrane-bound organelles.

Eukaryotic cell

A cell with a true, well-defined nucleus and membrane-bound organelles.

Prokaryotic domains

Bacteria and Archaea.

Eukaryotic domain

Eukarya.

Binomial nomenclature

The two-part system used to give organisms scientific names.

Binomial

"Two names"; refers to the two parts of a scientific name.

Scientific name format

Genus + specific epithet.

Genus in a scientific name

The first part of a binomial name; capitalized.

Specific epithet

The second part of a binomial name; lowercase.

Example of binomial nomenclature

Homo sapiens.

Carolus Linnaeus

Scientist associated with developing binomial nomenclature.

Phylogeny

The evolutionary history of a species or group of species.

Phylogenetic tree

A diagram representing evolutionary relationships among organisms.

Morphology

The physical characteristics or structures of organisms.

Morphological analysis

Using physical characteristics to compare organisms and infer relationships.

Molecular systematics

The analysis of molecular data such as DNA, RNA, and amino acid sequences to study genetic similarities and evolutionary relationships.

Molecular data

DNA, RNA, and amino acid sequence information used as evidence in molecular systematics.

Why molecular systematics is useful

Molecular similarities can provide better insight and confidence when determining phylogenetic relationships.

Closely related species and molecular sequences

Closely related species tend to have more similar DNA and amino acid sequences than more distantly related species.

Monophyletic group

A group containing a common ancestor and all of its descendants.

Clade

Another term for a monophyletic group.

Paraphyletic group

A group containing a common ancestor and some, but not all, of its descendants.

Monophyletic vs. paraphyletic

Monophyletic = ancestor + ALL descendants; Paraphyletic = ancestor + SOME descendants.

Reptiles and paraphyly

Reptiles were considered paraphyletic because birds, which descended from the relevant common ancestor, were excluded.

Purpose of phylogenetic trees

To represent and visualize evolutionary relationships among organisms.

Morphological vs. molecular evidence

Morphology uses physical characteristics; molecular systematics uses DNA, RNA, and amino acid sequence data.

What a closer branch point means in a phylogenetic tree

Organisms sharing a more recent common ancestor are more closely related.

Phylogenetic evidence

Morphological and molecular similarities can be used as evidence for evolutionary relationships.