IB T5 5 Classification

7/27/2019 IB T5 5 Classification

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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

IB T5 5 Classification

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