Population A2

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  • Population
    • Variation in population
      • Population growth curves
        • 1) A period of slow growth as the pop is small so reproduction takes time to increase population
        • 2) A period of rapid growth-population size doubles
        • 3) Stables state- no growth-fluctuations due to changes in factors e.g. food supply
      • Factors
        • Abiotic-Those concerned with non living parts of the environment.
          • pH
          • Light intensity
          • Temperature
          • Water and humidity
        • Biotic-Those concerned with the activities of living organisms and include competition, predation.
    • Competition
      • Two types:
        • Intraspecific competition-within species
          • Limpets/oak tree
        • Interspecfic competition-between species
          • When two species initially occupy the same niche-one has a competitive edge
    • Predation
      • Occurs when one organism is consumed by another.
      • Effects on predator-prey relationship
        • 1) Predators eat prey-thus reducing population
        • 2) Fewer prey mean predators have to compete so predators die
        • 3) Less predators mean more prey survive-population increases
        • 4) Predators now have ample food so population increases
    • Human population
      • Reasons for population explotions
        • Development of agriculture
        • Industrial revolution
      • Temporary reversals in upward trend
        • War
        • Disease
        • Famine
      • Factors effecting population rise
        • Birth/death rates
        • Immigration/ Emmigration
        • % pop growth rate in a given time
          • =
            • Pop change per year / pop at the beginning at time period
              • X 100
      • Factors effecting birth rate
        • Economic conditions
        • Culture/religious beliefs
        • Social pressures
        • Birth conrtol
        • Political factors
      • DTM
        • 1) small and stale-High birth and death rates    2)early expansion-high birth rates, decreasing death rates    3) Late expansion-decreasing birth rates, low death rates       4) Large and stable-Low birth and death rates
  • DTM
    • 1) small and stale-High birth and death rates    2)early expansion-high birth rates, decreasing death rates    3) Late expansion-decreasing birth rates, low death rates       4) Large and stable-Low birth and death rates

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