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
- Organisms adapting to environment
- 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
- Lag phase
- 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
- 1. High stationary stage
- 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
- Wide base, Narrow top
- 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
- Sigmoid population growth curve
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