Human populations

  • Created by: emma
  • Created on: 20-11-14 21:41
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  • Human Populations
    • Sigmoid population growth curve
      • Lag phase
        • Organisms adapting to environment
          • Make nest, food located, enzymes synthesised
      • Log phase
        • Exponential growth due to no limiting factors
      • Stationary phase
        • Factors start to limit population growth, population more or less constant
      • Decline phase
        • Population size decreases due to build up of toxic waste and limited resources
    • Calculations
      • Birth rate= no births in year/ total population that year X 100
      • Death rate= no deaths in year/ total population that year X 100
      • Rate of population growth= birth rate - death rate
      • % growth rate= change in population size/ population size at start X 100
    • Demographic transition
      • 1. High stationary stage
        • Stable population, High birth rate, High death rate, growth low
      • 2. Early expanding stage
        • Increasing population , High birth rate, falling death rate
      • 3. Late expanding stage
        • Increasing population, Falling death rate, low birth rate
      • 4. Low stationary stage
        • Stable population, Low birth rate, Low death rate
    • Average Life expectancy
      • Age at which 50% of population is still alive
    • Population Pyramids
      • Wide base, Narrow top
        • Developing country, high birth and death rate, DT stage 1
      • Narrower base, Wider top
        • Developed country, aging population, Low birth and death rate, DT stage 4
    • Factors effecting growth
      • Religion, some don't believe in contraception or abortion
      • Infant mortality rate high, have more children so chance of at least one surviving
      • Availability of contraception/ abortion
      • Economic conditions, poor countries have more children so they can work
      • Food suppy
      • Water supply and sanitation
      • Lack of health care, more deaths
      • Age profile, more elderly people more deaths
      • Development of industry and agriculture caused a large increase in human population


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