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Cambridge IGCSE Biology

Classification and Keys

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You will need to be able to:

• Define and describe the binomial system of naming species

• Use a dichotomous key to identify an unknown organism

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Biological classification:

Kingdom

Phylum

Class

Order

Family

Genus

Species

Animalia

Chordata

Mammalia

Carnivore

Felidae

Panthera

pardus

Taxonomic ranks

Panthera pardus

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The binomial system gives organisms a two word name showing the genus and species

Panthera leo Panthera tigris Panthera pardus

Genus species GenusGenus speciesspecies

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There are other classification systems:

• Cladistics:Based on similarity and differences between DNA and RNA sequences

Extended

AAAA

AACA

AGAA AGTA

AGGA

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You will need to be able to:

• Define and describe the binomial system of naming species

• Use a dichotomous key to identify an unknown organism

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Keys use a series of questions to identify unknown organisms

1. Stalk does not have a frill go to 2Stalk has a frill go to 3

2. Stem is brown Fungus AStem is yellow Fungus B

3. Cap has spots go to 4Cap does not have spots Fungus C

4. Cap is red Fungus DCap is brown Fungus E

frill

capIdentify the fungus

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Now you should be able to

• Define and describe the binomial system of naming species

• Use a dichotomous key to identify an unknown organism

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Cambridge IGCSE Biology

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