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IBSL Biology: Option G
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IBSL Biology: Option G


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International Baccalaureate students wishing to test out of Standard Level biology with Option G may find this useful.

International Baccalaureate students wishing to test out of Standard Level biology with Option G may find this useful.

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  • 1. Option GEcology and Conservation
  • 2. Distribution of Plant Species• Distribution of species is the range ofplaces a species inhabits• Linked directly to abiotic factors• Abiotic Factors:– Temperature, water, light, soil pH, salinity andmineral nutrients
  • 3. Distribution of Animal Species• Temperature: effects all animals, only some cansurvive in extreme temperatures• Water: animals vary in the amount of water theyrequire• Breeding sites: all species breed at some stage intheir life cycle• Food supply: many need specific foods and canonly live in areas where these foods areobtainable• Territory: some animals establish and defendterritories for feeding or breeding (creates an evendistribution)
  • 4. Random Sampling Using Quadrats• In a random sample, every individual in apopulation has an equal chance of beingselected• Quadrats: square frames used to mark outsample areas
  • 5. Transects and Distributions• Transect: line marked out across a sitewhich indicates where to investigateplant/animal distributions along– Useful when there is a gradient in an abioticfactor
  • 6. The Niche Concept• Ecological niche: the mode of existence of aspecies in an ecosystem– Habitat: where the species lives in an ecosystem– Nutrition: how the species obtains its food– Relationships: interactions with other species in theecosystem• Two species with a similar niche will compete inthe overlapping parts, yet will most likely coexist• Two species with exactly the same niche willalways compete and one will become superior• Competitive exclusions principle: only one speciescan occupy a niche in an ecosystem
  • 7. Fundamental and Realized Niches• Fundamental niche: potential mode ofexistence, given the adaptations of thespecies• Realized niche: actual mode of existence,results from its adaptations andcompetition from other species• Differences between the two niches aredue to competition
  • 8. Interactions Between Species• Herbivory: primary consumer feeding on a plant or otherproducer– relies on producer’s growth• Predation: consumer feeding on another consumer– relies on number of prey• Parasitism: organism that lives on or in a host and obtainsfood from it– Host is always harmed• Competition: two species using the same resource compete– When one species uses more of a resource the other speciessuffers• Mutualism: members of different species that live together in aclose relationship– Both benefit
  • 9. Measuring Biomass• Biomass: total dry mass of organic matterin organisms or ecosystems1. Representative samples are collected2. Organisms are sorted into trophic levels3. Organisms are dried in an oven from 60-80Celcius4. Mass is measured with an electronic balance5. Drying and measuring may be repeated
  • 10. Constructing Pyramids of Energy• The lowest bar of a pyramid of energy is the grossproduction (total amount of organic matterproduced by plants)• Energy flow measured in kilojoules of energy persquare meter per year• Net production: amount of gross production in anecosystem after subtracting the amount used byplants in respiration• Upper bars of a pyramid are the energy that flowthrough groups of consumers; amount of energy inthe food they eat
  • 11. Difficulties with Trophic Levels• Many species exist partly in one trophiclevel and partly in another• Examples:1. Chimpanzees eat fruit and plants, but alsotermites and larger animals; both first andsecond consumers2. Oysters consume ultraplanktonic producers,microplanktonic consumers, and deadorganic matter; first and second consumersas well as detritivores
  • 12. Ecological Succession• Ecological Succession: series of changes to anecosystem– Primary succession: starts in an environment whereliving organisms have not previously existed• New island created by volcanic activity– Secondary succession: areas where an ecosystem ispresent, but is replaced by other ecosystems,because of a change in conditions• Abandoned farmland developing into a forest• Common changes: soil erosion is reduced due toroots of large plants; amount of organic matter insoil increases as plants/organisms release moreorganic matter
  • 13. Biomes and Biosphere• Biome: a type of ecosystem– Determined mainly by rainfall andtemperature of the area• Biosphere: made up of the biomes of theworld together
  • 14. Major Biomes of the World• Desert: low rainfall, warm/hot days, cold nights, few plants• Grassland: low rainfall, warm/hot summers, coldwinters, grasses/herbs• Shrubland: cool wet winters, hot dry summers, fires, drought-resistant shrubs and evergreen foliage• Temperature deciduous forest: moderate rainfall, warmsummers, cool winters, trees that shed their leaves, shrubsand herbs• Tropical rainforest: High rainfall, hot in all seasons, hugediversity of plants• Tundra: low temps, little precipitation (mostly as snow), smalltrees, few herbs, mosses and lichens are present
  • 15. Biodiversity• Abbreviation of the term “biologicaldiversity” from 1986• Encompasses the diversity of ecosystemson Earth, the diversity of species withinthem, and genetic diversity of eachspecies
  • 16. The Simpson Diversity Index• Overall measure of species richness in anecosystem1. Collect random sample for organisms2. Identify each of the organisms found3. Count total number4. Calculate D (the index)N = total number of organismsn = number of individuals per species
  • 17. Reasons to Conserve Rainforest• Economic reasons: new commodities may befound (medicine, raw materials), new crops orfarm animals, ecotourism• Ecological reasons: fix large amounts of carbondioxide, damage can cause soil erosion, silting upof rivers, flooding, change in weather patterns• Ethical reasons: every species has a right to live,cultural importance to indigenous humans, deprivefuture humans the experience• Aesthetic reasons: beautiful and enjoyablespecies, artists find inspiration here
  • 18. Biomagnification• Biomagnification: the process by whichchemical substances become moreconcentrated at each trophic level• PCBs are chemicals that were used asinsulators used until 1970s that are nowdetectable throughout the world;Persistent and very toxic
  • 19. Impacts of Alien Species• Alien species: one that humans haveintroduced to an area where it does notnaturally occur• Causes interspecific competition andspecies extinction• Rats introduced to New Zealand killed offbird species (Big South Cape Island)
  • 20. Ozone and Ultra-Violet Radiation• Ultra-violet radiation damage:– Increases mutation rates by damaging DNA– Causes cancer (especially skin cancer)– Severe sunburns and cataracts of the eye– Reduces photosynthesis rates and so affectsfood chains• Without the Ozone layer there would be agreater amount of ultra-violet radiation• CFCs are the main cause of ozone depletion