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8.1 |
Classification System and Naming of Organisms |
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The Necessity of Classification System and Naming of Organisms |
- The Earth inhibited by millions organisms of different species.Many organisms are not found yet and identified their species
- Local name for an organism is not the same based on the regions and countries
- Hence,a scientific method of classification and nomenclature is required to ease research and communication as well as for reference at international level
- In the current classification system,all identified organisms are classified into six Kingdom.
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Taxonomy |
A field in biology which involves the classification, identification and naming of organisms in an organised manner.
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The Purpose of Taxonomy |
Manage information and data which has been collected using a systematic and methodical approach to elucidate the scientific community.
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Classification of Organisms |
- All organisms in the world can be categorised into six kingdoms which are:
- Archaebacteria.
- Eubacteria.
- Protista.
- Fungi.
- Plantae.
- Animalia.
- The organisms are classified based on types of cells, number of cells and types of nutrition.
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The Six Kingdoms |
- Prokaryote.
- Unicellular organism.
- Autotroph or heterotroph.
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- Prokaryote.
- Unicellular organism.
- Autotroph or heterotroph.
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- Eukaryote.
- Unicellular or multicellular organism.
- Autotroph or heterotroph.
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- Eukaryote.
- Unicellular or multicellular organism.
- Heterotroph.
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- Eukaryote.
- Multicellular organism.
- Autotroph.
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- Eukaryote.
- Unicellular or multicellular organism.
- Heterotroph.
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The Main Features of Organisms in Each Kingdom |
- Is a prokaryote organism.
- Unicellular organisms.
- Do not have a nucleus and membrane-enclosed organelles.
- Live in various habitats and extreme habitats such as anaerobic, high salt. concentration and high-temperature environments.
- Carry out anaerobic respiration.
- Do not sensitive to antibiotic.
- Carry out asexual reproduction such as binary fission and budding.
- Examples: methanogens, halophiles, thermophiles.
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- Is a prokaryote organism.
- Unicellular organisms.
- Do not have a nucleus and membrane-enclosed organelles.
- Have cell wall.
- Divided into gram-positive and gram-negative.
- Can carry out aerobic respiration, anaerobic respiration and fermentation.
- Sensitive to antibiotic.
- Certain bacteria can carry out photosynthesis.
- Carry out sexual reproduction and asexual reproduction such as binary fission and formation of spores.
- Examples of bacteria such as Escherichia coli, Streptococcus sp., Lactobacillus sp. and others.
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- Is a eukaryote organism.
- Unicellular organisms or a multicellular organisms.
- Have nucleus and membranous organelles.
- Lives in aquatic habitats.
- Divided into algae and protozoa.
- Carry out aerobic respiration.
- Only algae can carry out photosynthesis.
- Carry out sexual reproduction by conjugation and asexual reproduction such as binary fission and budding.
- Examples: Ameoba sp., Paramecium sp., Euglena sp., Sprigyra sp., Chlamydomonas sp. and others.
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- Is a eukaryote organism.
- Unicellular organisms and multicellular organisms
- Have nucleus and membranous organelles
- Live in various habitat
- Carry out aerobic respiration and fermentation
- Do not carry out photosynthesis
- As saprophytes or parasites
- Carry out sexual reproduction by conjugation and asexual reproduction such as budding and formation of spores
- The body is made up of a thread-like network of hyphae called the mycelium.
- Examples: fungi, yeast, mushrooms and other.
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- Is a eukaryote organism.
- Multicellular organisms.
- Have nucleus and membrane organelles.
- Live in various habitats.
- Carry out aerobic respiration and fermentation.
- Can carry out photosynthesis.
- Carry out sexual reproduction and asexual reproduction such as vegetative growth.
- Examples: ferns, pine trees, monocotyledonous plants, eudicot and others.
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- Multicellular organisms.
- Have nucleus and membrane organelles.
- Live in various habitats.
- Carry out aerobic respiration.
- Can carry out fermentation for certain tissues.
- Do not carry out photosynthesis.
- Carry out sexual reproduction.
- Some organisms can carry out asexual reproduction such as budding, regeneration, fragmentation and parthenogenesis.
- Examples: corals, jellyfish, worms, starfish, spiders, insects, fish, reptiles, birds, mammals and others.
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Taxonomy Hierarchy |
- The hierarchy system used in taxonomy is the Linnaeus hierarchy system.
- The Linnaeus hierarchy system classifies organisms according to hierarchy, starting from species to domain.
- The orders of the hierarchy are domain, kingdom, phylum, class, order, family, genus and species.
- Domain:
- The highest taxonomic rank of organisms in the hierarchical biological classification system.
- Spesies: The most specific hierarchy of classification.
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Binomial Nomenclature System |
- The formal system of naming organisms practised today is called the Linnaeus binomial system.
- Scientific method.
- In italics or underlined separately.
- Two Latin names:
- The first name is genus and starts with a capital letter
- The name given is based on genetic relation
- The second name is species and starts with a small letter
- The name given is based on scientist name ,place of discovery and characteristics
- The method to write write the scientific name of an organism is as shown below:
- Each scientific name consists of two words: the first word is the name of the genus, the second word is the name of the species.
- The first letter of the genus is capitalised while the name of the species is not.
- All scientific names must be printed in italics. If handwritten, the two names must be underlined separately.
- The example on how to write scientific names is as shown belows:
Common Name |
Genus Name |
Species Name |
Scientific name (Handwritten) |
Scientific name (Printed) |
Common kingfisher |
Alcedo |
atthis |
Alcedo atthis |
Alcedo atthis |
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Dichotomous Key |
- A tool used by taxonomists to identify organisms based on similarities and differences.
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Ways to Build A Dichotomous Key |
- Determine a particular characteristics which can classify a group of organisms into two categories
- Divide the organisms of the same category into another two categories until each organism is identified
- The number of steps required to classify organisms is the number of organisms (m) required to be identified minus one, that is m-1.
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