5.5.1 Outline the binomial system of nomenclature.(2)

Outline means to give a brief account or summary

Each species has two names. These are used together to give a precise reference to this species.

• Genus is given first and is always written with an upper case letter. e.g. Homo

• Species epithet follows the genus and is written in lower case e.g. sapiens

Therefore the species name for humans is Homo sapiens

Conventions:

• If written by hand the name should also be underlined

• If typed the name should really be in italics but this convention is often ignored

• Often the name will be followed by another name in brackets e.g. (Dickson) which refers to the first person to scientifically identify the species.

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5.5.2 List seven levels in the hierarchy of taxa—kingdom, phylum, class, order, family, genus and species—using an
example from two different kingdoms for each level.(1)

 

 

 

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5.5.3 Distinguish between the following phyla of plants, using simple external recognition features: bryophyta, filicinophyta, coniferophyta and angiospermophyta.(2)

Kingdom: Plantae

Characteristics:

• Photosynthetic

• Chlorophyll

• Cellulose cell wall

• Vacuoles permanent

• Store starch

 

 

 

Classification of the major plant phyla is based on external observable structures:

Phylum: Bryophyta (mosses, liverworts and hornworts)

 

• stems radial symmetry (mosses)

• stems bilateral symmetry (liverworts), no lignin

• no true leaves or roots

• no cuticle.

• reproductive structure are called sporangium which are on long stalks with capsules on end. In this image the spore is released from the sporangium to develop into another plant.

 

 

 

 

 

Phylum: Filicinophyta (ferns)

 

• leaves

• roots non woody stems

• divided leaves

• height up to 20m

• reproduction: sporangia (sori) contain reproductive spores

 

 

 

Phylum: Coniferophytes (conifers and pines)

• trees (100m), shrubs,

• woody (lignin) stems,

• waxy narrow needle like leaves.

• vascular system (tracheids)

• reproduction:monoecious, microsporophylls (male) non motile gametes often with air bladders for water/ air dispersal. macrosporophylls (female) ovule on cone scale

 

 

 

Phylum: Angiospermophyta (flowering plants and grasses)

• roots

• stems

• leaves.

• vascular bundles (xylem/ phloem )

• waxy cuticle,

• annual or perennial up to 100m

reproduction:

• ovules in an enclosed carpel structure.

• pollen grains produced from anthers

• variety of pollen transfers vectors

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5.5.4 Distinguish between the following phyla of animals, using simple external recognition features: porifera, cnidaria, platyhelminthes, annelida, mollusca and arthropoda.(2)

The syllabus specifies six of the 30 or more phyla from the animal kingdom. The ones selected are what might be called invertebrates. This term describes the common feature of the group which lack a notochord (spinal cord ). The Kingdom of animals is classified according to these characteristics:

• Heterotrophic

• no cell walls

• no vacuoles

• no chlorophyll

• store glycogen

The six phyla are classified according to features such as the number of layers in the body plant, the opening for mouth and anus along with the method of support. Phylogenic studies (evolutionary relationship) relies more on genetic studies to support the modern classification of these groups.

Phylum: Porifera (sponges)

• No body layers rather there is an aggregate of different cell types.

• Support is from either silica or calcium based spicules which link together to provide some support.

• Body plan is built around water canals that circulate nutrient through the sponge for ingestion by specialised cells.

• There is no mouth or anus

 

 

 

Phylum: Cnidaria (Jelly fish, Sea anemones, Corals)

• These have 2 layers in the body plan.

• There is a radial symmetry.

• Jelly fish are mobile organisms. Sea anemones are sessile organisms.

• Single entrance that serves the the cavity that functions of the circulation of respiratory gases and nutrient. These organisms are secondary consumers and posses stinging cells with toxins called nematocysts to disable prey.

• Corals secrete a CaCO₃ skeleton

 

 

 

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

 

Phylum: Annelida (segment worms)

3 layers to the body plan / bilateral symmetry

body divided into ringed segments with some specialisation of segments

Mouth connected via gut to a separate anus.

Skin surface used for gas exchange.

Many marine forms but also terrestrial species usually soil burrowing

 

 

 

Phylum: Mollusca (Snails, slugs and octopus)

Bilateral symmetry with significant modification.

• An extraordinarily varied group which has developed some radically divergence from other groups.

• Phylogenic studies place them closer to annelids than other groups.

• Body plan has three major features:

• Foot, a muscular structure used for movement and burrowing.

• Central visceral mass containing all the organ structures (separate mouth and anus)

• Mantle a folded membrane structure that can surround other tissues and create a cavity containing a gill.

• The mantle frequently secretes a calcareous shell.

 

 

 

 

Phylum: Arthropoda ( Insects, Crustaceans, Spiders, Scorpions, Millipedes)

• 3 layer body plant with bilateral symmetry.

• Hard exoskeleton composed of chitin.

• Jointed body segments.

• Jointed appendages.

• Some flying organisms in the class Insecta. ( 10⁶⁺ species)

• Separate mouth and anus.

 

 

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5.5.5 Apply and design a key for a group of up to eight organisms.(3)

Design Principles:

• Each question divides the group of organisms into two smaller groups based on a pair of alternative characteristics

• Subsequent groups may focus on more minor detail

• In most cases the characteristic will be readily observed or measurable

• It is better to choose characteristics that are not influenced by the environment

• Shape and number are often good characteristics on which to base alternative pairings of questions

• A complete key will have each type of organism classified separated along with a final identifying name.

Below is a gallery of species with their common names

1. Try to create a dichotomous key for the identification of these animals.

2. When complete give this to another student to test.

3. As a last resort there is an example of one of many possibilities for you to inspect.

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Click4Biology:5.5 Classification