Card Set Information
AQA BIOL4 Human population
What 4 things is human population dependant on?
How do you calculate population growth?
(Births+Immigration) - (Deaths+emigration)
How do you calculate percentage growth rate?
change in population multiplied by 100, divided by the population at the start
How do you calculate birth/death rate?
Number of births/deaths per year divided by total population that year
How do you calculate the rate of natural increase?
Births-deaths per year divided by total population per year
What is a population pyramid?
A diagram showing the age structure of a population with bars denting the percentage of males and females at each age range
What are features of a population pyramid for an MEDC?
Narrow base (low birth rate)
Vertical sides (low infant mortality rate)
Tall height (many survive to old age)
What are features of a population pyramid for an LEDC?
Wide base (high birth rate)
Sloping sides (high infant mortality rate)
Short height (few people surviving to old age)
What is a survival curve?
A graph showing the lifespans of individuals from a sample group of 10,000
How can the average life expectancy of a population be calculated from its survival curve?
By looking at the age when 50% of the population are still alive
What is shown by a growth curve?
The size of a population plotted against time
State 4 social or economic factors that affect the growth of a population
Safe drinking water
Effective sewage disposal
Effective medical care (vaccinations)
Describe stage 1 of the DTM
: High birth and death rates
High infant mortality and short lifespans due to starvation and disease
Population remains low and stable
Describe stage 2 of the DTM
: Population increased due to high birth rates.
Better nutrition and less disease decreases death rates
Describe stage 3 of the DTM
Late expanding: Birth rate lower due to birth control and less dependance on children to contribute to income
Describe stage 4 of the DTM
: Stable population Low birth and death rates
Greater proportion of old people in the population