Biology Classification System

Classification Scheme

• People use the binomial system (two-part naming system) to classify organisms.
• Carolus Linnaeus/Carl von Linné developed this system in the mid-1700s.
• Taxonomy is the science of naming and classifying living things.
• Organisms are initially grouped according to observable characteristics (phenotype).
• The classification is now based largely on genotype (DNA sequence).
• Classification examples include Kingdom Animalia and Domain Eukarya.

Example: Human Classification

• Humans are composed of eukaryotic cells.
• Humans belong to the Kingdom Animalia.
• Humans belong to the Phylum Chordata.
• Humans belong to the subphylum Vertebrata, and subphylum Mammalia.
• Humans belong to the class Mammalia, subclass Eutheria, and order Primates.
• Humans belong to the family Hominidae.
• Humans belong to the genus Homo.
• Humans belong to the species Sapiens.

Kingdoms and Domains

• Originally, living things were classified into two large groups: plants and animals.
• Now, there are five kingdoms: plants, animals, fungi, protists, and monera (prokaryotes).
• Living things are now further classified into three domains: Bacteria, Archaea, and Eukarya.

Prokaryotes

• Prokaryotes have existed for 4-3.5 billion years, which is about 80% of Earth's history.
• Prokaryotes are present in various environments, from high temperatures to ice to high radiation.
• Prokaryotes are the most abundant life form on Earth.
• Prokaryotes play a vital role as decomposers, recycling vital elements.
• Prokaryotes are identified by their shapes (e.g. spherical - cocci, rod-shaped - bacilli, spiral-shaped - spirillum) and different metabolic properties (aerobic, anaerobic, facultative anaerobic).

Environments

• Chemoautotrophs/Lithotrophs use inorganic chemicals for energy instead of sunlight.
• Endospores allow some bacteria to survive harsh environmental conditions.
• Endospores are like a dormant 'seed' form of the bacteria.

Plant Classification

• Plants are organized into terrestrial, non-vascular, seedless, vascular plants, non-flowering seed, and flowering seed groups.

Kingdom Plantae

• Plants are organized into four different groups: seedless nonvascular, seedless vascular, nonflower seed, and flowering seed plants.
• The sporophyte is the dominant generation in ferns and related species; the gametophyte is the dominant generation in bryophytes.

Gymnosperms

• Gymnosperms (naked seed) are vascular, non-flowering seed plants.
• Examples include conifers (pines, firs, spruces, etc.) and cycads, and other important plant families.
• Reproduction in gymnosperms is independent of water.
• Gymnosperms have a variety of uses (lumber, etc.)

Angiosperms

• Angiosperms (flowering seed plants) are the dominant plant group.
• Angiosperms display co-evolution with pollinators (vector carries pollen).
• Flowers attract pollinators through visual and olfactory cues.
• Angiosperms have reproductive structures (sepals, petals, stamens, and carpels).
• Angiosperms developed fruits for seed dispersal.

Plant Structure

• Plants have shoot systems and root systems.
• Leaves can take diverse forms (e.g., spines, tendrils, etc.).
• The plant body is made up of three tissue systems: epidermal, vascular, and ground tissue.
• The epidermis forms a protective layer.
• Water transport occurs through xylem.
• Food transport occurs through phloem.

Plant Growth

• Plant growth is indeterminate.
• Plants grow throughout their life cycle.
• Some plants (annuals) complete their life cycles in a single year or season; others (perennials) live and reproduce for multiple years.

Fungi

• Fungi are mostly multicellular (yeasts are a unicellular exception).
• Fungi are heterotrophs.
• Fungi secrete digestive enzymes that aid in nutrient uptake.
• The fungal body is composed of filaments called hyphae.
• Fungi have several groups: Zygomycota, Ascomycota, and Basidiomycota.
• Fungi play important ecological roles as decomposers.

Animal Intro

• Animals are eukaryotic, multicellular, heterotrophic organisms without cell walls.
• Most animals are bilaterally symmetrical (have a left and right side).
• Cephalization (development of a head with sensory organs) is prominent in bilaterally symmetrical animals.
• Several different phyla are considered, including: Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Mollusca, Arthropoda, Echinodermata, and Chordata.

Chordata

• Chordates have a notochord, a dorsal hollow nerve cord, pharyngeal gill slits, and a post-anal tail.
• Fish, amphibians, reptiles, birds, and mammals are included in Chordata.
• Key characteristics vary within classes (e.g., possession of jaws, presence of swim bladders, adaptations for terrestrial living).

Kingdom Protista

• Protists are a diverse group of eukaryotes.
• Protists can be autotrophic or heterotrophic.
• Important groups include protozoans (e.g., flagellates, amoebas, apicomplexans, ciliates), slime molds, and algae.

Algae

• Algae are unicellular (one cell) or multicellular.
• Algae exhibit photosynthetic traits and are autotrophic.
• Include many different phyla such as Chlorophyta (green algae), Pyrrhophyta (dinoflagellates), and Chrysophyta (diatoms).

Ecology

• Ecology studies the interactions between organisms and their environment.
• Ecology is multi-level: molecular, cellular, organismal.
• Organisms interact with one another through factors such as competition, predation, and symbiotic relationships.

Community Ecology

• Communities are defined by the presence of multiple species within a limited area.
• Trophic levels describe the feeding relationships within a community.
• Producers make their own food, whereas consumers rely on producers or other consumers.
• Trophic levels may consist of producers, primary consumers, secondary consumers, tertiary consumers, etc.
• Humans play a crucial role as consumers; their activities influence the ecosystem.

Tab 4 and Tab 5

• Energy limits and trophic levels: a tremendous amount of energy enters the world from the sun but less is passed on at each trophic level.
• Specific consumers (dominant, keystone, and foundation species) influence ecosystem structure and function.
• Species with higher abundance or biomass are called dominant species.
• Keystone species play a vital role in ecosystem function.
• Foundation species influence physical and biological environment.