Biodiversity, Evolution & Classification
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- Created by: Kirsty_hodnett
- Created on: 18-05-15 21:14
Biodiversity
- human alteration to habitat is the single greatest threat to biodiversity
- destroying tropical rainforests
- overfishing
- clearing lands for crop production/human populations
- extinction is a natural process occuring since the first life evolved
- current rate underlies biodiversity problems
- human activity increasing rate of extinction at alarming rate
- mass destruction for farming agriculture urbanisation forestry mining drilling pollution
- earlier extinctions e.g dinosaurs where a result of climatic geological biotic changes
- main causes of loss of large mammals are loss of habitat over hunting and competition from introduced species, and deforestation pollution and wetland drainage
- each species can represent an important human asset
- food, chemicals, disease resistant genes
- extinction of plant species with potential medicinal properties before being fully investigated could be an incalcuable loss
- need for species consrvation and preservation of wildlife
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Evolution
- processes that have transformed life on Earth from its early beginings tovast diversity of fossilised and living forms known
- theory proposed by Charles Darwin
- travelled to south america and galapogas islands formed in recent geological time by volcanic activity
- studied flora and fauna on both lands- any plants on the islands must have reached via the mainland
- observe describe and classify his findings, colecting fossils showing the different life forms of the past
- natural selection was the force to cause changes in the populations
- studied finches onislands, which are unable to fly long distances as such to reach the mainland
- acestors of the finches reached the island by prevailing winds species flourished due to no other bird species and a variety of food individual finches differed in size and shape of beaks related to type of food eaten seeds fruit insects
- characteristics best suited to the finch where passed to offspring, all finches had common ancestor type of beak developed through adaptie radiation via food
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Taxonomy & Phylogeny
- sorting living groups of organisms into groups of a managable size
- look for differences and similarities between organisms placing similar organisms close and different ones apart
- hierarchical system devised to distinguish large groups of organisms with a series of rank names
- kingdom, phylum, class, order, family, genus, species
phylogeny
- taxonomic ranks based on evolutionary line of descent
- phylogenic relationships represented by a tree
- oldest speces at the base while recent at the ends
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Binomial System
- naming according to the binomial system based on latin
- each organism has two names, genus and species
- precise identification worldwide
- each organism has unique scientific name and allows for easy identification of relation to other species
- genus name is the fiirst word and has a capital
- species name comes second with no capital
- first time used in a scientific text should be names in full afterwards it can be abbreviated
- printed in italics or underlined
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5 Kingdom Classification
prokaryote
- unicellular organisms incl. bacteria and blue green algae
- no organelles
- cell wall not of cellulose
proctoctista
- small eukaryotic organisms
- membrane bound organelles and nucleus
- not plant animals or fungi incl. algae mouldss slime protozoa
fungi
- eukaryotic with a body of a sytem of threads called hyphae forming a mycelium
- rigid cell wall of chitin
- no photosynthetic pigments; feed heterotrophically- saprophytic/parasitic
- reproductionby spores w/o flagellum yeast mushroom
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5 Kingdom Classification p2
Plants
- multicellular
- carry out photosynthesis
- eukaryotes with cellulose walls, vacuoles with cell sap & chloroplasts with photosynthetic pigments
- mosses liverworts frns conifers flowering plants
animals
- multicellular
- heterotrophic eukaryotes
- cells do not have cell walls
- nervous coordination
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Animal Kingdom Phyla - annelida
- non-chordates/invertebrates
- chordates- vertebrates with a vertebral column
annelida
- earthworms leeches
- long thin segmented ringed body separated internally by septa
- fluid filled body cavity
- hydrostatic skeleton
- head with primative brain/nervous system
- thin permeable skin for gaseous exchange
- closed circulatory system with repiratory pigment
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Arthropoda
- body divided into segments
- well developed brain
- open circlatory system/cavity surrounding body organs
- hard outer exoskeleton
- paired jointed legs
- key features
- joined legs modified for a variety of functions swimming jumping walking
- exoskeleton for protection of internal organs, attachment of muscle, suppor, reducing water loss
- exoskeleton does not grow- must be shed leaving animal vunerable
- classes
- crustacea 10-20 pairs of legs
- spiders 4 pairs
- insects 3 pairs
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Arthropoda Insecta
- most successful group- inhabt most habitats and air
- adult insects have different features to other arthropods
- 3 pairs of legs, one to each segment of thorax
- head has antennae and compound eyes
- gas exchange by gills in aquatic forms and tracheae in terrestrial
- evolved wings, only invertebrate to fly
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Chordata
- frogs snakes eagles humans
- vertebral column or backbone
- well developed brain enclosed in a cranum
- fish- scales gills fins aquatic
- amphibians- first land vertebrates, semi terrestrial, soft moist skin, eggs fertilised externally in water. young are aquatic with gills adults normally terrestial with simple lungs
- reptiles- mainly terrestial with dry scaly skin, lungs and internal fertilisation of eggs with a shell and laid on land
- birds- fly and have feathers, forelegs adapted as wings, lungs, and eggs with hard shell
- mammals- skin with hair, born alive and fed on milk, lungs
- marsupials- kangaroo- young born immaturely and develop in pouch
- placentals- young born developed from womb, recieve nourishment via placenta before birth
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Common Ancestry
- structures that may have different functions but are similar suggest common origin= homologous. pentadactyl limb of chordata adapted to the need of the vertebrate= human arm, bat wing, whale flipper, horse leg
- possible to construct evolutionary trees
- similar structures developed as a result of environmental conditions performing the same function= analogous bird and insect wings
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Genetic Evidence
- new speices develops differences in the sequencing of nucleotide bases in DNA
- over time these differences accumilate as a result of evolution
- DNA anaylsis confirms evolutionary relationships reducing the number of mistakes in classification due to convergent evolution
- DNA hybridisation involves extraction and comparison of DNA of two species, sequence of bases compared and the more alike the more closely related
- sequence of amino acids determined by DNA degree of similarity n amino acid sequence of the same protein in 2 species reflects the relationship
- enables scientists to draw evolutionary tree for mammals
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Immunological Techniques
- antibodies of one species respod to antigens on proteins in the blood of another
- when they respond a precipitate is formed
- more precipitate= more closely related
- human serum injected into bunny>rabbit serum containing anti-human antibodies> added to other species serum
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