Lecture 2: Biological Classifications

Vocabulary flashcards covering key terms from Lecture 2 on biological classifications, including taxonomic ranks, the three domains, and overviews of the major kingdoms.

Taxonomy

The branch of biology devoted to naming and classifying organisms.

Aristotle's Two-Kingdom System

Early classification that divided all living things into plants and animals.

Carl von Linné (Carolus Linnaeus)

Swedish naturalist who introduced the modern two-part scientific naming system.

Binomial Nomenclature

System that gives every species a two-word Latin name consisting of genus and species.

Genus

Taxonomic category containing closely related species; first word of a scientific name.

Species

Group of organisms capable of interbreeding; second word of a scientific name.

Linnaean Hierarchy

Eight major taxonomic ranks: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Domain

Highest taxonomic rank that groups related kingdoms; life is divided into three domains.

Universal Ancestor

Hypothetical organism at the base of the evolutionary tree from which all life descended.

Tree of Life

Diagram depicting evolutionary relationships among all organisms.

Bacteria

Domain of prokaryotic, asexual, single-celled organisms that are metabolically diverse and abundant.

Prokaryotic Cell

Cell lacking a membrane-bound nucleus and organelles.

Archaea

Domain of prokaryotic, single-celled organisms without peptidoglycan and often living in extreme environments.

Peptidoglycan

Structural molecule in bacterial cell walls that is absent in archaea.

Extremophile

Organism that thrives in extreme conditions, common among archaea.

Eukarya

Domain containing all organisms with eukaryotic cells, including protists, plants, fungi, and animals.

Eukaryotic Cell

Cell with a membrane-bound nucleus and organelles.

Protists

Mostly single-celled eukaryotes that are not plants, animals, or fungi; nutritionally and reproductively diverse.

Photosynthesis

Process by which plants and some protists convert sunlight, CO₂, and water into glucose.

Chlorophyll

Green pigment that allows plants to capture solar energy for photosynthesis.

Chloroplast

Plant cell organelle where photosynthesis occurs.

Autotrophic

Able to produce organic food molecules from inorganic sources; self-feeding.

Heterotrophic

Obtaining energy by consuming other organisms; not self-feeding.

Fungi

Multicellular eukaryotes with hyphae that absorb nutrients; important decomposers.

Hyphae

Thread-like structures forming the body of a fungus and absorbing nutrients.

Decomposer

Organism that breaks down dead organic matter, recycling nutrients in ecosystems.

Symbiotic Relationship

Close interaction between different species, often beneficial; common with fungi.

Animals

Multicellular, motile, heterotrophic eukaryotes that mostly reproduce sexually.

Vertebrates

Animals with a backbone; represent about 4 % of the animal kingdom.

Invertebrates

Animals without a backbone; make up the vast majority of animal species.