Biology 1 - Mod 7 Populations

Population density

number of individuals per unit area

Age structure

the number of males and females of each age group that a population contains

Immigration

movement of individuals into an area occupied by an existing population

Emigration

movement of individuals out of an area

Exponential growth

growth pattern in which the individuals in a population reproduce at an increasing rate

Logistic growth

growth pattern in which a populations growth slows and the stops following a period of exponential growth

Carrying capacity

largest number of individuals of a particular species that a particular environment can support

Limiting factor

factor that causes population growth to decrease

Density-dependent limiting factor

limiting factor that depends on population density

Density-independent limiting factor

limiting factor that affects all populations in similar ways regardless of the population density.

Demography

scientific study of human populations

Demographic transition

change in a population from high birth and death rates to low birth and death rates

Biological magnification

Increasing concentration of a harmful substance in organisms at higher trophic levels in a food chain or food web

aquaculture

raising of aquatic organisms for human consumption

ecological footprint

Total amount of functioning ecosystem needed both to provide the resources a human uses and to absorb the wastes that a population generates

ecological hot spot

Small geographic area where a significant number of habitats and species are in immediate danger of extinction

acid rain

precipitation containing nitric and sulfuric acids.

biodiversity

total of the variety of organisms in the biosphere

habitat fragmentation

splitting of ecosystems into pieces

ozone layer

Atmospheric layer in which ozone gas is relatively concentrated; protects life on earth from UV rays in sunlight

genetic diversity

Sum total of all different forms of genetic information carried by a particular species, or by all organisms on Earth

species diversity

number of different species that make up a particular area

smog

gray-brown haze formed by a mixture of chemicals

Sustainable Development

Strategy for using natural resources without depleting them and for providing human needs without causing long-term environmental harm