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Classification


CHARACTERISTICS OF LIFE

  • Specific size and shape
  • Metabolism - the sum of all the chemical activities of the cells that provide for an organism's growth, maintenance and repair
  • Movement - Some organisms have obvious movement from muscular contraction (e.g. swim, fly, run). Some move by beating of cilia or flagella, or oozing like an amoeba. Others like corals and oysters do not move from place to place.
  • Irritability - response to a stimulus (e.g. light or chemicals such as food)
  • Growth - increase in cellular mass, and/or increase in number of cells
  • Reproduction - formation of another organism. Since viruses cannot reproduce on their own without being inside a host cell, they are not regarded as living organisms.
  • Adaptation - ability to adapt to an environment, by either seeking a more suitable environment, or by undergoing modifications to be better fitted to its present surroundings

TAXONOMY TERMS

  • Taxonomy - the hierarchical system of naming, describing and classifying organisms using structural characteristics
  • Structural Characteristics - the features of an organism relating to structure (e.g. radial or bilateral symmetry, asexual or sexual reproduction, number of appendages, backbone, shape of leaf)
  • Characteristics that are not used in classification - As organisms to be identified are often dead, preserved in alcohol, and not usually in their normal habitat, certain characteristics are not useful in identification (e.g. body temperature, habitat, movement, colour).
  • Reasons for Classification
  1. To provide a scientific name that is accepted and communicated by scientists from different countries
  2. To show relationships between groups
  3. To identify organisms accurately (e.g. poisonous organisms)
  • 5 Kingdoms - Biologists generally classify living organisms into 5 large groups or kingdoms - Kingdom Monera (simple micro-organisms), Kingdom Protista (complex micro-organisms), Kingdom Fungi, Kingdom Plantae and Kingdom Animalia.
  • Classification within a Kingdom - Kingdom, Phylum (or Division), Class, Order, Family, Genus, Species
  • Mnemonic for Remembering the Classification within a Kingdom - King Paul Cries Out For Good Soup

5 KINGDOMS

MAIN

CHARACTERISTICS

EXAMPLES

Monera
  • Unicellular (single-celled)
  • Cell wall usually
  • Bacteria
  • Cyano-bacteria
  • (blue-green algae)

Protista
  • Unicellular
  • Paramecium
  • Amoeba
  • Some algae
  • Slime moulds
Fungi
  • Unicellular or multicellular (many-celled)
  • Cell wall
  • No chloroplasts
  • Mushrooms
  • Moulds
  • Yeast
Plantae
  • Unicellular or multicellular
  • Cell wall
  • Chloroplasts for photosynthesis
  • Ferns
  • Pine trees
  • Roses
Animalia
  • Unicellular or multicellular
  • No cell walls nor chloroplasts
  • Humans
  • Coral
  • Spider

MAKING A DICHOTOMOUS KEY

Classification

Example: Here are two examples of keys to show how to key out organisms, such as a kangaroo, a cow, a bee and a spider. Shown are a branching key and a numbered key.

Classification

1a. Internal skeleton …………………… go to 2
1b. No internal skeleton …………………… go to 3
2a. Pouch present …………………… kangaroo
2b. Pouch absent …………………… cow
3a. Six legs …………………… bee
3b. Not six legs …………………… spider