HideShow resource information


  • Tropical rainforests depleting - make room for and support increasing population.
  • Ocean's, stocks of fish depleting - over harvesting, stress on coral reefs and estuaries.
  • Human alteration - greatest threat to biodiversity.
1 of 13


  • A natural process - rate of extinction biodiversity crisis.
  • Human activity in tropical areas has increased extinction rates between 1000 and 10000 times.
  • Massive destruction of habitats - brought by agriculture, urban development, forestry, mining ane pollution.
  • Marine life also affected - one-third of fish rely on coral reefs, half of reefs could be lost in the next 20 years.
  • Earths earlier occupants became extinct due to - climatic, geological and biotic changes.
  • Main cause for loss of animals - loss of habitat, over hunting by humans, competition from introduced species, deforestation, pollution and drainage of wetlands.
  • Reason's for extinction - potential source of food, useful chemicals or disease resistant genes.
2 of 13


  • The process by which new species are formed from pre-existing ones over very long periods of time.
  • Processes which have transformed the life on earth from early beginnings to vast diveristy of fossilised and living forms today.
  • First proposed by Charles Darwin - studied the flora and fauna of the Galapagos islands and South America.
  • Individual finches differed from one island to the next depending on what food was available.
  • Characteristics best suited a particular finch to its environment - all developed from a common ancestor the beak had developed over time - adaptive radiation.
3 of 13


  • Kingdom - Animals/Plants
  • Phylum - Insects/Spiders/Centipedes/Millipedes/Crustaceans.
  • Class - Insecta
  • Order - Orthoptera
  • Family - Roasaceae
  • Genus - Locusta
  • Species - Locusta migratoria

King Patrick Comes Over For Great Sandwiches

4 of 13


  • The hierchical order of taxonomic ranks based on evolutionary line of descent.
  • Oldest species at the base.
  • More recent ones at the ends of the branches.
  • Most related organisms come off same branch.
5 of 13

Five Kingdom Classification

  • Prokaryotae
    • Bacteria and blue green algae.
    • No internal cell membranes.
    • No nuclear membrane.
    • No Endoplasmic Reticulum.
    • No Mitochondria.
    • No Golgi body.
    • Possess a cell wall - not made from cellulose.
  • Protoctista
    • Small eukaryotic organisms.
    • Membrane-bound organelles.
    • Nucleus with a nuclear membrane.
    • Organisms not plants/animals/fungi.
    • Includes algae/water moulds/slime moulds/protozoa/
  • Animals
    • Multicellular
    • Heterotrophic
    • Eukaryotes - cells lack cell walls and show nervous co-ordination
6 of 13

Five Kingdom Classification

  • Fungi
    • Eukaryotic.
    • Network of threads called hyphae - form a mycelium.
    • In subgroups hyphae have no cross-walls - in others cross-walls/septa are present.
    • Rigid cell wall made of chitin.
    • No photosynthetic pigments.
    • Feeding heterotrophic.
    • Members either saprophytic or parasitic.
    • Reproduction through spores which lack flagella.
    • Penicillium/Yeast/Mushroom
  • Plants
    • Multicellular.
    • Carry out photosynthesis.
    • Cells eukaryotic - cellulose walls, vacuoles containing cell sap, chloroplasts containing photosynthetic pigments.
    • Mosses/liverworts/ferns/conifers and flowering plants
7 of 13


  • Include earthworms/leeches and lugworms.
  • Have a long, thin body, segmented body - segments visible as rings body divided internally by partitions (septa).
  • Fluid filled body cavity (haemocoel)
  • Hydrostatic skeleton.
  • Head with primitive brain and nervous system running whole length of body.
  • Thin permeable skin - gaseous exchange occurs here.
  • Closed circulatory system containing an oxygen-carrying pigment.
8 of 13


  • Body divided into segments.
  • A well-developed brain.
  • Open circulatory system and cavity surrounding body organs.
  • Paired jointed legs - for walking, swimming, jumping, feeding, reproduction.
  • Hard outer exoskeleton - outermost layer of cells of body, secretes thick cuticle consists mainly of chitin.
    • Protection of internal organs.
    • Point of attachment for muscles
    • Support.
    • Exoskeleton covered in layer of wax reducing water loss.
    • Fixed in size, does not grow.
    • Arthropod must shed its exoskeleton leaving it vulnerable.
  • Myriopoda - many pairs of legs - millipedes and centipedes.
  • Crustacea - 10 and 20 pairs of legs - crab
  • Spiders - four pairs of legs.
  • Insects - three pairs of legs.
    • Three pairs of legs - one pair to each segment of the thorax.
    • Head has antennae and compound eyes.
    • Gas exchange by gills in aquatic insects and tracheae in terrestrial forms.
9 of 13


Frogs, snakes, eagles and humans.

  • Vertebrates - posses vertebral column or backbone.
  • Well-developed brain, enclosed in cranium.
  • Subdivided into:
    • Fish - aquatic forms with scales, fins and gills.
    • Amphibians - first land vertebrates, partly terrestrial and partly aquatic, soft moist skin/eggs fertilized in water/larvae aquatic and have gills/adults terrestrial have simple lungs.
    • Reptiles - mainly terrestrial, have dry skin with scales, lungs, eggs fertilisd internally, covered with shell, laid on land.
    • Birds - able to fly, development of feathers, fore legs developed as wings, lungs, hard shell.
    • Mammals -skin with hair, born alive, fed on milk, lungs either;
      • Marsupials - young born at immature state develop in females pouch.
      • Placentals - young undergo development in mothers womb, recieve nourishment via placenta.
10 of 13

Evidence of common ancestry

  • Evolution suggests widely separated groups of organisms share a common ancestor - therefire share basic structual features.
  • How similar they are indicates how closely related they are in terms of evolution.
  • Groups with little in common are assumed to have diverged from a common ancestor much earlier in geological history than groups with a lot in common.
11 of 13

Using physical features

  • Homologous - having a common origin but serve a different function
  • Pentadactyl (having five digits) limb of chordata found in; vertebrates, amphibians, reptiles, birds and mammals.  Structure of the limb is basically the same in all classes, however the limbs of different vertebrates have become adapted for different functions; grasping, walking, swimming and flying.
  • Examples of pentadactyl limb - human arm, wing of a bat, flipper of a whale, wing of a bird, leg of a horse.
  • Using info. like this can help construct evolutionary trees where the end products of evolution have certain structual features in common with each other and with ancestral stock.
  • The more similar - the more recent to have diverged.
  • Analagous - having the same function but different origin.
  • Shark and Dolphin have similar fore-limbs because they live in similar envirnments and have become adapted to that environment - not because of a similar ancestor.
12 of 13

Using genetic evidence

  • Convergent evolution - the tendecy of unrelated organisms to acquire similar structures.
  • DNA hybridisation:
    • Extraction and comparison of DNA of two species.
    • Sequence of bases compared, more alike sequences, closer organisms are related in terms of evolution.
    • Sequence of amino acids in proteins determined by DNA.
    • Degree of similarity in amino acid sequence of same protein in two species will reflect how closely related the two species are.
    • Fibrinogen molecule of mammals compared and sequence differes in varying degrees from one species to another - scientists drawn up evolutionary tree for mammals.
  • Immunological techniques:
    • Proteins of different species compared.
    • Antibodies of one species will respond to specific antigens in proteins i.e. albumin in blood serum.
    • Antibodies will respond to corresponding antigens - precipitate forms - greater degree of precipitate closer the evolutionary relationship.
13 of 13


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Biodiversity, evolution and classification resources »