6) Biological Diversity & Taxonomy Lecture Notes

Biological Diversity

The variety of life forms on Earth, differing in shape, form, size, and ecological roles.

Taxonomy

Branch of biology concerned with identifying, naming, and classifying organisms.

Binomial Nomenclature

Two-part scientific naming system devised by Carolus Linnaeus (genus + species).

Genus

First part of a scientific name; a group of closely related species.

Species

Basic taxonomic unit; group of populations that can interbreed and produce fertile offspring.

Tautonymy

Scientific name in which genus and species epithets are identical (e.g., Vulpes vulpes).

Scientific Name Formatting

Genus capitalized; genus and species italicized/underlined; e.g., Homo sapiens.

Domain

Broadest taxonomic category; Bacteria, Archaea, or Eukarya.

Taxon

Any taxonomic unit at any level (plural: taxa).

Bacteria

Domain of prokaryotes with peptidoglycan cell walls; diverse in form and habitat.

Archaea

Domain of prokaryotes adapted to extreme conditions; lack peptidoglycan walls.

Eukarya

Domain of organisms with membrane-bound nuclei and organelles.

Microbiota

Community of microorganisms living in and on another organism (e.g., human body).

Prokaryote

Unicellular organism lacking a nucleus; includes Bacteria and Archaea.

Cocci

Spherical prokaryotic cells.

Streptococci

Chains of cocci bacteria.

Staphylococci

Clusters of cocci bacteria.

Bacilli

Rod-shaped prokaryotic cells.

Spirilla

Short, rigid spiral-shaped prokaryotes.

Spirochete

Long, flexible spiral-shaped prokaryote.

Extreme Halophiles

Archaea that thrive in very high salt concentrations.

Extreme Thermophiles

Archaea that thrive in very high temperature (often acidic) environments.

Methanogens

Anaerobic archaea that produce methane as a metabolic by-product.

Gram-positive Bacteria

Bacteria with thick peptidoglycan walls that retain violet stain; often soil dwellers.

Gram-negative Bacteria

Bacteria with thin peptidoglycan and outer membrane; do not retain violet stain.

Proteobacteria

Large group of Gram-negative bacteria sharing rRNA sequence; includes E. coli.

Cyanobacteria

Photosynthetic, plant-like bacteria; ancestors of chloroplasts.

Chlamydias

Obligate intracellular bacterial parasites of eukaryotic hosts.

Spirochetes (Group)

Helical bacteria that move by rotating; include syphilis and Lyme agents.

Streptomyces

Soil Gram-positive bacteria source of many antibiotics (e.g., streptomycin).

Escherichia coli

Common intestinal proteobacterium; model organism; can be pathogenic.

Vibrio cholerae

Proteobacterial pathogen that causes cholera.

Eukaryote

Organism whose cells contain a true nucleus and organelles.

Protist

Any eukaryote that is not a plant, animal, or fungus; often unicellular.

Algae

Photosynthetic protists; produce oxygen and form base of aquatic food webs.

Diatoms

Unicellular algae with silica cell walls; major component of plankton.

Dinoflagellates

Protists with two flagella; some cause red tides, others nourish corals.

Ciliates

Protists that move/feed using numerous cilia; e.g., Paramecium.

Paramecium

Ciliate protist known for slipper shape and rapid ciliary movement.

Amoeba

Protist that moves and feeds using pseudopodia.

Fungi

Kingdom of heterotrophic eukaryotes that absorb nutrients via extracellular digestion.

Hyphae

Threadlike fungal filaments forming the body and feeding structures.

Mycelium

Interwoven mass of hyphae serving as the feeding network of a fungus.

Mycorrhiza

Mutualistic association between fungal hyphae and plant roots.

Lichen

Symbiotic partnership of a fungus with green algae or cyanobacteria.

Chitin

Polysaccharide composing fungal cell walls and arthropod exoskeletons.

Spore

Reproductive cell capable of developing into a new fungus without fusion.

Yeast

Unicellular fungus that reproduces by budding.

Basidiomycetes

Club fungi producing spores on basidia; include mushrooms.

Plantae

Kingdom of multicellular, photosynthetic eukaryotes with cellulose cell walls.

Bryophytes

Seedless, nonvascular plants such as mosses, liverworts, hornworts.

Lycophytes

Seedless vascular plants including club mosses, spike mosses, quillworts.

Monilophytes

Seedless vascular plants such as ferns, horsetails, whisk ferns.

Gymnosperms

Non-flowering seed plants; seeds not enclosed in fruit (e.g., conifers).

Angiosperms

Flowering plants; seeds develop within protective ovaries (fruits).

Xylem

Vascular tissue conducting water and minerals upward in plants.

Phloem

Vascular tissue transporting sugars and other organic nutrients in plants.

Animalia

Kingdom of multicellular, heterotrophic organisms that ingest food.

Invertebrate

Animal lacking a vertebral column (backbone).

Vertebrate

Animal possessing a backbone made of vertebrae.

Radial Symmetry

Body plan with parts radiating from a central axis (e.g., jellyfish).

Bilateral Symmetry

Body plan with mirror-image left and right sides and distinct head/tail.

Protostome

Animal whose embryonic first opening (blastopore) becomes the mouth.

Deuterostome

Animal whose blastopore becomes the anus; mouth forms secondarily.

Phylum Porifera

Sponges; simplest animals without true tissues, filter feeders.

Choanocyte

Flagellated sponge cell that drives water flow and captures food.

Amoebocyte

Sponge cell that moves nutrients and forms skeletal fibers.

Cnidocytes

Stinging cells unique to cnidarians for defense and prey capture.

Flatworms (Platyhelminthes)

Acoelomate worms; include planarians, flukes, and tapeworms.

Mollusks

Soft-bodied animals with foot, visceral mass, mantle; many have shells.

Radula

Rasping, tongue-like feeding organ of many mollusks.

Annelids

Segmented worms such as earthworms and polychaetes.

Segmentation

Repetition of body sections, seen in annelids and arthropods.

Nematodes

Roundworms with complete gut and protective cuticle; many are parasites.

Cuticle (Nematode)

Tough outer layer preventing desiccation in nematodes.

Arthropods

Segmented animals with jointed appendages and chitinous exoskeleton.

Exoskeleton

External skeleton providing support and protection in arthropods.

Chelicerates

Arthropods with grasping mouthparts; spiders, scorpions, horseshoe crabs.

Myriapods

Millipedes and centipedes; many-segmented arthropods with numerous legs.

Pancrustaceans

Clade including crustaceans and insects.

Echinoderms

Marine deuterostomes with spiny skin and water-vascular system.

Endoskeleton (Echinoderm)

Internal calcium-rich plates supporting echinoderm bodies.

Chordates

Animals possessing a notochord, dorsal nerve cord, slits, and tail at some stage.

Notochord

Flexible rod providing support in chordate embryos/adults.

Pharyngeal Slits

Openings in the pharynx region of chordate embryos; modified for various uses.

Post-anal Tail

Muscular tail extending beyond the anus in chordates.

Lancelets

Small, fish-like invertebrate chordates retaining all four key traits as adults.

Tunicates

Sac-like marine chordates; adults are filter-feeding invertebrates.

Cartilaginous Fish

Jawed fish with skeletons of cartilage; sharks and rays.

Ray-finned Fish

Bony fish with thin, flexible fin rays; most familiar fish species.

Lobe-finned Fish

Fish with muscular, limb-like fins; include lungfish and coelacanths.

Tetrapods

Jawed vertebrates with two pairs of limbs adapted for land.

Amphibians

Tetrapods with aquatic larvae and terrestrial adults; need moist skin.

Amniotes

Tetrapods producing amniotic eggs or equivalents; reptiles, birds, mammals.

Ectotherm

Animal regulating body temperature via environmental heat ("cold-blooded").

Endotherm

Animal generating internal heat to maintain body temperature.

Mammals

Endothermic amniotes with hair and mammary glands.

Placenta

Organ linking mammalian embryo to mother for nutrient and gas exchange.

Marsupials

Mammals whose young develop in an external pouch after birth.

Eutherians

Placental mammals bearing fully developed live young.