Organizing the Living World

 

ž  The LINNAEAN HIERARCHY

¡  Developed by Carolus Linneaus

¡  Species is the lowest level of classification

¡  Closely related species grouped together to form a genus

¡  The scientific name (species) of an organism is its genus name followed by the specific epithet.

ž  Homo sapien

ž  Linnaean Hierarchy

¡  Kingdom

¡  Phylum

¡  Class

¡  Order

¡  Family

¡  Genus

¡  Species

¡  Domain

ž  Not included in original Linnaean designations, but adopted by many biologists

ž  Bacteria: : unicellular, reproduce asexually, lack membrane-bound organelles

ž  Archaea: same physically as most bacteria, but live in harsh environments and differ genetically

ž  Eukarya: membrane-bound organelles

ž  Living organisms are most often classified using:

¡  Evolutionary Trees

¡  Linnaean Hierarchy

¡  Three Domains

ž  Organisms can also be identified as “prokaryotes” or “eukaryotes”

¡  PROKARYOTES

ž  Simple, but successful

ž  Majority of life on earth

ž  Can live nearly anywhere

ž  Reproduce asexually

ž  One individual = 1 million overnight

ž  Diverse methods of obtaining nutrition

ž  Photosynthesize

ž  Ingest other organisms

ž  Consume carbon-containing compounds

ž  Derive carbon from inorganic compounds

ž  Bacteria and Archaea are prokaryotes with key differences

ž  Archaea have unique DNA

ž  Different metabolisms

ž  Structural differences in cell walls and plasma membranes

ž  Archaea are the “extremophiles”

ž  Play important roles in biosphere and human society

ž  Bacteria convert nitrogen to nitrate, which plans depend on and can’t make themselves

ž  Important food source for some organisms

ž  Important decomposers

¡  EUKARYOTES

ž  Cells contain organelles bound by membranes

ž  Ex: nucleus, mitochondria, chloroplasts

ž  PROTISTS

ž  Primarily single-celled

ž  Diverse in size, shape, lifestyle

ž  Reproduce sexually

ž  Can cause disease

ž  Do not have all the defining characteristics of a plant, animal, or fungus

ž  PLANTS

ž  Great pioneers

ž  Capable of turning barren ground into productive ecosystems

ž  Diverse:Include simple mosses to massive fruiting trees

ž  Major Groups of Plants

ž  Bryophytes: simple plants without vascular tissue (xylem and phloem)

ž  ex. Mosses

ž  Seedless Vascular: vascular tissue, but do not produce seeds

ž  ex. Ferns

ž  Gymnosperms: vascular tissue, seeds that are not enclosed (many are cone-bearing)

ž  ex. Pine trees, other Conifers, Cycads, Ginkgos

ž  Angiosperms: vascular tissue, seeds are enclosed, produce flowers

ž  ex. Flowering plants, fruit trees, etc.

ž  FUNGI

ž  Lack vascular tissue, nonmotile

ž  Often difficult to understand

ž  Much of the organism remains hidden from view

ž  Are grouped according to their method of reproduction

ž  Decomposers: speed the return of nutrients in dead and dying organisms to the ecosystem

ž  Utilize hyphae

ž  Parasites: live in/on other organisms and harm them

ž  Mutualists: benefit from and provide benefits to the organism they associate with

ž  ANIMALS

ž  Multicellular organisms with complex features

ž  Tissues: specialized, coordinated collections of cells

ž  Ex: Sponges, Cnidarians

ž  Organs and organ systems

ž  Ex: Flatworms, human digestive system

ž  Complete body cavities

ž  Ex: Protostomes and Deuterostomes

ž  Wide variety of complex behaviors

ž  Capture prey, eat prey, avoid being prey, attract mates, care for young, migrate, etc.

ž  Play key roles in ecosystems

ž  Consumers, decomposers, spread plants seeds and fungal spores, can be pests, etc.