bio lecture 1

Vocabulary flashcards covering phylogeny concepts (tree structure, synapomorphy, homoplasy), taxonomy (domains, binomial nomenclature, genus/species), and the origins of photosynthesis and atmospheric oxygen (cyanobacteria, stromatolites, nitrogen fixation).

Phylogeny

The evolutionary history of a group of organisms, depicted as a branching tree showing relationships and common ancestry.

Nested hierarchy

A hierarchical arrangement where groups are nested within larger groups, reflecting diversification over time.

Clade

An ancestor and all of its descendants; a monophyletic group on a phylogenetic tree.

Sister groups

Two lineages that diverged from a common ancestor and are each other’s closest relatives.

Root (of a phylogenetic tree)

The origin point representing the earliest common ancestor of the included taxa.

Branch (in a phylogenetic tree)

A lineage segment from a node to its descendant lineages.

Synapomorphy

A derived trait shared by members of a clade that indicates common ancestry.

Homoplasy

Similar traits that evolved independently (convergent evolution) or by reversals, not from a common ancestor.

Domain (of life)

One of three highest taxonomic levels: Bacteria, Archaea, and Eukarya.

Bacteria

A domain of prokaryotic organisms lacking a nucleus; one of the three domains of life.

Archaea

A domain of prokaryotic organisms distinct from bacteria, often thriving in extreme environments.

Eukarya

A domain of organisms with cells that contain a true nucleus and membrane-bound organelles.

Binomial nomenclature

The two-part scientific naming system for species: Genus + species epithet (e.g., Amorphophallus titanum).

Genus

A taxonomic category comprising one or more related species.

Species

The basic unit of biological classification; a group capable of interbreeding and producing fertile offspring.

Authority (in a species name)

The person or team who first validly described and named the species; often listed after the species name.

Photosynthesis

Process by which light energy converts CO2 and H2O into glucose and O2; overall reaction summarized as 6CO2 + 6H2O → C6H12O6 + 6O2.

Cyanobacteria

Photosynthetic prokaryotes that performed oxygenic photosynthesis; key players in building Earth's oxygen-rich atmosphere and in some cases nitrogen fixation via heterocysts.

Oxygenic photosynthesis

Photosynthesis that produces molecular oxygen as a byproduct.

Stromatolites

Layered sedimentary structures formed by photosynthetic microorganisms (including cyanobacteria), providing evidence of early life and photosynthesis.

Nitrogen fixation

Conversion of atmospheric N2 into ammonia and related nitrogen species; essential for synthesizing amino acids and nucleic acids; some cyanobacteria fix nitrogen in specialized cells called heterocysts.

Heterocysts

Specialized nitrogen-fixing cells in some cyanobacteria that protect the nitrogenase enzyme from oxygen.

Origin of Earth’s oxygen atmosphere

The buildup of atmospheric oxygen due to oxygenic photosynthesis, enabling aerobic life and the diversification of eukaryotes.

Stromatolite evidence

Ancient layered structures formed by photosynthetic microorganisms that provide insight into early life and the history of photosynthesis.