5.5 Classification


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IB Topic 5: Ecology

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5.5 Classification

  1. 1. 5.5: Classification Topic 5: Ecology & Evolution Miss Friedman
  2. 2. 5.5.1: Binomial system of nomenclature <ul><li>Designed by Carolus Linneaus in 18 th century </li></ul><ul><li>Based on idea that every species has a Latin name, made up of two parts </li></ul><ul><li>First part is the name of the genus </li></ul><ul><li>Second part specifies the species </li></ul><ul><li>Name should be printed in italics (underlined if hand written) and first part capitalized </li></ul><ul><li>Example </li></ul><ul><li>Humans are Homo sapiens </li></ul>
  3. 3. 5.5.2: Hierarchical system of classification <ul><li>Organisms that share characteristics are placed into similar groups </li></ul><ul><li>The more similar their characteristics, the closer the grouping </li></ul><ul><li>The purpose of classification is to: </li></ul><ul><ul><li>Clearly identify an organism with a name that is unique to the species and avoids confusion with local naming </li></ul></ul><ul><ul><li>Show evolutionary links </li></ul></ul><ul><ul><li>Allow us to predict anatomical, physiological and genetic characteristics it may share with other organisms </li></ul></ul>
  4. 4. <ul><li>The Hierarchical system has seven levels called taxons (plural: taxa) </li></ul><ul><li>Each taxon can contain one or more of the sub-group below it </li></ul><ul><li>The seven level hierarchies of taxa are: </li></ul><ul><ul><ul><li>Kingdom </li></ul></ul></ul><ul><ul><ul><li>Phylum </li></ul></ul></ul><ul><ul><ul><li>Class </li></ul></ul></ul><ul><ul><ul><li>Order </li></ul></ul></ul><ul><ul><ul><li>Family </li></ul></ul></ul><ul><ul><ul><li>Genus </li></ul></ul></ul><ul><ul><ul><li>Species </li></ul></ul></ul>
  5. 6. 5.5.3: Plant Phyla <ul><li>Kingdom: Plantae </li></ul><ul><li>Characteristics: </li></ul><ul><ul><ul><li>Photosynthetic </li></ul></ul></ul><ul><ul><ul><li>Chlorophyll </li></ul></ul></ul><ul><ul><ul><li>Cellulose cell wall </li></ul></ul></ul><ul><ul><ul><li>Permanent vacuoles </li></ul></ul></ul><ul><ul><ul><li>Stores starch </li></ul></ul></ul><ul><li>Classification of the major plant phyla is based on external observables structures </li></ul>
  6. 7. <ul><li>Need to know: </li></ul><ul><ul><li>-Bryophyta -angiospermophyta </li></ul></ul><ul><ul><li> -Filicinophyta -Coniferophyta </li></ul></ul>
  7. 8. Phylum: Bryophyta (Mosses, Liverworts, Hornworts) <ul><li>Small terrestrial plants </li></ul><ul><li>Do not have true roots, stems or leaves but they must have structures resembling them </li></ul><ul><li>Leaf-like structures are often arranged in a spiral </li></ul><ul><li>Usually have live in clusters which act like sponges holding water </li></ul><ul><li>No cuticle </li></ul><ul><li>Reproductive structures are called sporangium which is on long stalks with capsules on end. </li></ul>
  8. 9. Phylum: Filicinophyta (ferns) <ul><li>Have true leaves </li></ul><ul><li>New leaves unroll </li></ul><ul><li>Divided leaves </li></ul><ul><li>Have an underground creeping stem (rhizome) </li></ul><ul><li>Height up to 20m </li></ul><ul><li>Reproduction: sporangia (sori) contain reproductive spores </li></ul>
  9. 10. Phylum: Coniferophytes (conifers & pines) <ul><li>All conifers are woody plants, most are trees with a single wooden trunk with side branches </li></ul><ul><li>Leaves are waxy, long thin needles, often arranged in spirals, often a dark green colour </li></ul><ul><li>Produce seeds found in cones </li></ul><ul><li>Vascular system (tracheids) </li></ul>
  10. 11. Phylum: Angiospermophyta (flowering plants and grasses) <ul><li>Have flowers, although they may be small in wind-pollinated angiospermophyta </li></ul><ul><li>Seeds are ovaries which become the fruit </li></ul><ul><li>Leaves usually as leaf blade and leaf stalk, with veins visible on the lower surface </li></ul><ul><li>Leaves have waxy cuticle </li></ul><ul><li>Vascular bundles (veins) are made </li></ul><ul><li>up of xylem & phloem </li></ul>
  11. 12. 5.5.4: Animal phyla <ul><li>The kingdom of animals is classified according to these characteristics: </li></ul><ul><ul><ul><li>Heterotrophic </li></ul></ul></ul><ul><ul><ul><li>No cell walls </li></ul></ul></ul><ul><ul><ul><li>No vacuoles </li></ul></ul></ul><ul><ul><ul><li>No chlorophyll </li></ul></ul></ul><ul><ul><ul><li>Store glycogen </li></ul></ul></ul>
  12. 13. <ul><li>The syllabus specifies 6 of the 30 or more phyla from the animal kingdom that you are responsible for knowing </li></ul><ul><li>The ones selected are what might be called invertebrates (lack of a spinal cord) </li></ul><ul><li>The six phyla are classified according to features such as: </li></ul><ul><ul><li>Number of layers in the body plant </li></ul></ul><ul><ul><li>The opening for mouth and anus </li></ul></ul><ul><ul><li>Method of support </li></ul></ul><ul><li>Phylogenic studies (evolutionary relationship) relies on more genetic studies to support the modern classification of these groups. </li></ul>
  13. 14. Phylum: Porifera (sponges) <ul><li>No body layer, rather there is an aggregate of different cell types </li></ul><ul><li>Support is from either silica or calcium based spicules which link together to provide some support </li></ul><ul><li>Body plan is built around water canals that circulate nutrients through the sponge for ingestion by specialized cells </li></ul><ul><li>There is no mouth or anus </li></ul>
  14. 15. Phylum: Cnidaria (Jelly fish, Sea anemones, Corals) <ul><li>They have two layers in the body plan </li></ul><ul><li>There is radial symmetry </li></ul><ul><li>Jelly fish are mobile organisms. Sea anemones are sessile organisms </li></ul><ul><li>Single entrance that serves the cavity that functions as circulation of respiratory gases and nutrients </li></ul><ul><li>These organisms are secondary consumers and posses stinging cells with toxins called nematocysts to disable prey </li></ul><ul><li>Corals secrete a CaCO 3 skeleton </li></ul>
  15. 16. Phylum: Platyhelminthes (flatworms) <ul><li>3 layers in the body plan </li></ul><ul><li>One entrance to “gut” which can have many folds to increase surface area. </li></ul><ul><li>Largely parasitic, includes flukes </li></ul>
  16. 17. Phylum: Annelida (segment worms) <ul><li>3 layers to the body plan </li></ul><ul><li>Bilateral symmetry </li></ul><ul><li>Body is divided into ringed segments with some specialization of segments </li></ul><ul><li>Mouth is connected via gut to a separate anus </li></ul><ul><li>Skin surface is used for gas exchange </li></ul><ul><li>Many marine forms but also terrestrial species, usually soil burrowing </li></ul>
  17. 18. Phylum: Mollusca (Snails, Slugs, Octopus) <ul><li>Bilateral symmetry with significant modification </li></ul><ul><li>Body plan has three major features </li></ul><ul><ul><li>Foot, a muscular structure used for movement and burrowing </li></ul></ul><ul><ul><li>Central visceral mass, contains all the organ structures (separate mouth & anus) </li></ul></ul><ul><ul><li>Mantle, a folded membrane structure that can surround other tissues and create a cavity containing ag ill. The mantle frequently secretes a calcareous shell. </li></ul></ul>
  18. 19. Phylum: Arthropoda (Insects, Crustaceans, Spiders, Scorpions, Millipedes) <ul><li>3 layer body plant with bilateral symmetry </li></ul><ul><li>Hard exoskeleton composed of chitin </li></ul><ul><li>Jointed body segments </li></ul><ul><li>Jointed appendages to each segment </li></ul><ul><li>At least 3 pairs of jointed legs </li></ul><ul><li>Some flying organisms in the class Insecta </li></ul><ul><li>Separate mouth and anus </li></ul><ul><li>Many free-living but also some parasitic </li></ul>
  19. 20. 5.5.5: Dichotomous Keys <ul><li>Each questions divides the group of organisms into two smaller groups based on a pair of alternative characteristics </li></ul><ul><li>Subsequent groups may focus on more minor details </li></ul><ul><li>In most cases the characteristic will be readily observed or measurable </li></ul><ul><li>It is better to choose characteristics that are uninfluenced by environmental variation </li></ul><ul><li>Shape and number are often good characteristics on which to base alternative pairings </li></ul><ul><li>A complete key will have each type of organisms being classified separated with a final identifying name </li></ul>