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    Question ID:   6797         Current Version: 1
Question: Could you explain the four factors that produce changes in population size?
Category: Science > Environment & Ecology
Keywords: explain, four, factor, produce, change, determine, population, size
Type: other
Rating:(0 ratings)    Views: 8053    Discussions: 0   In Watch Lists: 1  

 
    Answer:

The four factors that determine population size are:

  • Birth rate: the ratio between births and individuals in a specified population and time
  • Mortality rate: the ratio between deaths and individuals in a specified population and time
  • Immigration: arrivals of new settlers from other countries
  • Emigration: people leaving to live in another country

For developed countries where birth rates have declined, immigration helps to keep or even increase the population size. 

Age structure also affects the population size. More women in primary child-bearing ages (15 - 40) may make it possible for rapid population size increase. Government policies can also influence population size by encouraging smaller families, encouraging adoption of children already born, and discouraging new births. Other factors affecting population size include health care or the lack of health care, epidemics (such as AIDS), losses through war, etc. Lack of prenatal care for expectant mothers, failure to protect children from communicable diseases (like measles) or widespread diseases (like malaria) can contribute to a smaller population. Economic development, family planning, and economic opportunities for women could reduce birth rates.

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