Core Biology - Topic 1 Classification
- 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
Plantae - multicellular, autotrophic feeders using chlorophyll, cell walls made of cellulose, complex cell structure - nucleus
Fungi - multicellular, 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
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
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
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
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
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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