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5.5: ClassificationTopic 5: Ecology & Evolution
Miss Friedman
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5.5.1: Binomial system of nomenclature
Designed by Carolus Linneaus in 18 th century Based on idea that every species has a Latin
name, made up of two parts First part is the name of the genus Second part specifies the species
Name should be printed in italics (underlinedif hand written) and first part capitalizedExample
Humans are Homo sapiens
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5.5.2: Hierarchical system of classification
Organisms that share characteristics are placedinto similar groups
The more similar their characteristics, the closerthe grouping
The purpose of classification is to:Clearly identify an organism with a name that is uniqueto the species and avoids confusion with local namingShow evolutionary links
Allow us to predict anatomical, physiological and geneticcharacteristics it may share with other organisms
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Need to know:
-Bryophyta -angiospermophyta
-Filicinophyta -Coniferophyta
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Phylum: Bryophyta(Mosses, Liverworts, Hornworts)
Small terrestrial plants Do not have true roots, stems or leaves but they
must have structures resembling them Leaf-like structures are often arranged in a spiral Usually have live in clusters which act like sponges
holding water
No cuticle Reproductive structures are called sporangium
which is on long stalks with capsules on end.
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Phylum: Filicinophyta(ferns)
Have true leaves New leaves unroll
Divided leaves Have an underground creeping stem
(rhizome)
Height up to 20m Reproduction: sporangia contain
reproductive spores
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Phylum: Coniferophytes (conifers & pines)
All conifers are woody plants, most are treeswith a single wooden trunk with sidebranches
Leaves are waxy, long thin needles, oftenarranged in spirals, often a dark greencolour
Produce seeds found in cones Vascular system (tracheids)
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Phylum: Angiospermophyta (flowering plants and grasses)
Have flowers, although they may be small inwind-pollinated angiospermophyta
Seeds are ovaries which become the fruit Leaves usually as leaf blade and leaf stalk,
with veins visible on the lower surface
Leaves have waxy cuticle Vascular bundles (veins) are made
up of xylem & phloem
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5.5.4: Animal phyla The kingdom of animals is classified
according to these characteristics: Heterotrophic No cell walls No vacuoles No chlorophyll Store glycogen
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The syllabus specifies 6 of the 30 or more phylafrom the animal kingdom that you areresponsible for knowing
The ones selected are what might be calledinvertebrates (lack of a spinal cord)
The six phyla are classified according to features
such as:Number of layers in the bodyThe opening for mouth and anusMethod of support
Phylogenic studies (evolutionary relationship)relies on more genetic studies to support themodern classification of these groups.
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Phylum: Porifera(sponges)
No body layer, rather there is an aggregate of different cell types
Support is from either silica or calcium basedspicules which link together to provide somesupport
Body plan is built around water canals that
circulate nutrients through the sponge foringestion by specialized cells There is no mouth or anus
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Phylum: Cnidaria(Jelly fish, Sea anemones, Corals)
They have two layers in the body plan There is radial symmetry Jelly fish are mobile organisms. Sea anemones are
sessile organisms Single entrance that serves the cavity that
functions as circulation of respiratory gases andnutrients
These organisms are secondary consumers andposses stinging cells with toxins callednematocysts to disable prey
Corals secrete a CaCO 3 skeleton
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Phylum: Platyhelminthes(flatworms)
3 layers in the body plan One entrance to gut which can have many
folds to increase surface area. Largely parasitic, includes flukes
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Phylum: Arthropoda(Insects, Crustaceans, Spiders,
Scorpions, Millipedes) 3 layer body with bilateral symmetry Hard exoskeleton composed of chitin
Jointed body segments Jointed appendages to each segment At least 3 pairs of jointed legs
Some flying organisms in the class Insecta Separate mouth and anus Many free-living but also some parasitic
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5.5.5: Dichotomous Keys Each questions divides the group of organisms into two
smaller groups based on a pair of alternativecharacteristics
Subsequent groups may focus on more minor details In most cases the characteristic will be readily observed or
measurable It is better to choose characteristics that are uninfluenced
by environmental variation
Shape and number are often good characteristics on whichto base alternative pairings A complete key will have each type of organisms being
classified separated with a final identifying name
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