Chapter 35 POPUALTION Flashcards
(18 cards)
Population?
A group of organisms of the same species that live in the same area at the same time.
Population growth?
Increase in nr of individuals in a population. Affected by biotic and abiotic factors.
What are the biotic factors that influence population growth?
Food supply Predation Diseases Size of ecosystem Competitors
Community?
All the populations of different species in an ecosystem.
Ecosystem?
A unit containing the community of organisms and their environment, interacting together.
What is a carrying capacity?
Max population size that an environment can support.
Factors affecting human population growth?
Natality more than mortality, increase Mortality more than natality, decrease Mortality = natality, zero growth Immigration increase Emigration decrease Poverty, fertility rate, socio-economic factors
Why has the human population increased?
- absence of limiting factors
- improvements in food supply
- Development to control diseases
- infant mortality decreased
- life expectancy increased
Why has the number of infectious diseases decreased?
- sewege treatments (fewer diseases (dysentery))
- Hygienic handing of food, less cases of food poisoning
- general standards of cleanliness (eliminated some diseases (typhoid))
- immunisation against infectious diseases
- antibiotics to treat bacterial diseases
Why has food production increased?
- more land brought under cultivation, bc of machinery and equipment
- agriculture became more efficient bc of modern technology
- fertilizers increase crop yield
- pesticides controls diseases and pests, fewer crops destroyed.
What is a population pyramid?
Graphical illustration shows distribution of various age groups in population, forms shape of pyramid when population growing.
LEDC?
Low economically developed country
Features of pyramids of LEDC?
- wide base, narrow tip
- base wide, high birth rate
- reduce upwards, infant mortality
- ranges present youth wide, future pressure job, housing needs
- little elderly; difficult living conditions, precarious healthcare services, short life expectancy.
MEDC?
More economically developed country
Features of pyramid of MEDC?
- Narrower birth rate, birth rate not so high
- stabilised human population
- adult age ranges generally wider than infentile ranges, showing there is no population growth.
- high number elderlies, quality life good, population access to healthcare services and good nutrition
Expansive?
Young population growing
Stationery?
Population not growing/growing slowly
Constrictive?
Population elderly and shrinking
