Core Biology - Topic 1 Classification

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  • Created by: Katie
  • Created on: 12-04-13 18:04

Classification

  • Aristotle  384 BCE - 322 BCE
    • one of the first people classify organisms by their characteristics
    • any organisms that did not move were plants

KINGDOM - PHYLUM - CLASS - ORDER - FAMILY - GENUS - SPECIES

  • Organisms are clasified into 1 of 5 kingdoms based on very basic characteristic

Animalia - mulitcellular, heterotrophic feeders so no chlorophyll, no cells walls, complex cell structure - nucleus

Plantaemulticellular, autotrophic feeders using chlorophyll, cell walls made of cellulose, complex cell structure - nucleus

Fungimulticellular, saprophytic feeders so no chlorophyll, cell walls not made of cellulose, complex cell structure - nucleus

Protoctista - mostly unicellular (a few are multicellular), complex cell structure - nucleus

Prokaryotae - unicellular, simple cell structure - no nucleus

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Classification Continued

Unicellular - single cells

Multicellular - made of many cells

Autotrophic - make their own food using photosynthesis

Heterotrophic - eating and digesting other organisms internally

Saprophytic - digesting other organisms externally

  • No virus kingdom
    • most scientists do not class them as being alive
  • Virus particles enter a living cell and change the way the cell works
    • causing it to make copies of the virus
  • However the virus particle does not show any other life process
    • e.g. growth or feeding
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Vertebrates and Invertebrates

  • Classifying some animals is hard when characters differ to the rest of the group
    • Many characteristics are looked at when deciding where to place an organism
  • Vertebrates - animals that have a backbone
    • series of small bones called vertebrae
    • all vertebrates belong to phylum Chordata
      • because of their supporting rod that runs the length of their body
  • Invertebrates - animals that do not have a backbone

Grouping vertebrates - OXYGEN ABSORBTION

  • fish have gills to take oxygen from water
    • young amphibians also have gills
  • adult amphibians usually have lungs/can absorb oxygen through their moist skin
  • mammals, reptiles and bids have lungs
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Vertebrates and Invertebrates Continued

Grouping vertebrates - REPRODUCTION CHARACTERISTICS

  • external fertilisation - female releases eggs into water, fertilised by sperm released by male
  • internal fertilisation - sperm released so fertilisation of eggs takes place inside females body
  • oviparous - lay eggs
    • e.g. birds, reptiles, amphibians, fish
  • viviparous - give birth to live young
    • e.g. mammals

Grouping vertebrates - THERMOREGULATION

  • homeotherms - maintain a constant body temperature, often warmer than their surroundings, by releasing heat from reactions in their body
  • poikilotherms - body temperature varies with the temperature of their surroundings
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Species

  • Species - a group of organisms that can interbreed to produce fertile offspring
    • last column of classification level
  • Hybrids - when 2 closes related species have produced offspring thats neither one nor the other species (often infertile but not always)
    • creates problems with the definition of a species
  • Many plants and fungi can reproduce from parts of themselves
  • Bacteria and many protoctists may reproduce by splitting in half
    • meaning each new indiviual has one parent
  • Mallard ducks hybridise with other closely related species producing fertile offspring
    • these offspring then breed with other hybrids or closely related ducks
    • continuous range of characteristics not seperate species
  • Members of the same species living nearby may have slightly different characteristics
  • Sometimes there's a chain of different popultions that can breed with neighbouring populations by the two at either end of the chain cannot interbreed
  • Forms a ring shape - RING SPECIES
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Species Continued

  • Every organism has a scientific name made of two Latin words
    • the genus and the species
    • BINOMIAL SYSTEM
  • Panthera leo - LION
  • Panthera tigris - TIGER
  • Organisms that share the first word are closely related
  • Useful if organisms have the same 'common name'
    • e.g. two quite different organisms are known as a 'robin'
  • System is agreed by scientists all over the world
    • allows them communicate clearly in any language
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