2. Population density is the number of individuals that live in a defined area.
Population density is a measurement of the number of individuals living in a defined space.
Scientists can calculate population density.

3. Population dispersion refers to how a population is spread in an area.
Geographic dispersion of a population shows how individuals in a population are spaced.
Clumped
dispersion
Uniform
Random
Population dispersion refers to how a population is spread in an area.

4. There are three types of dispersion.
clumped

5. There are three types of dispersion.
uniform

6. There are three types of dispersion.
random

7. Survivorship curves
1. low level of infant mortality and an older population
common to humans
2. survivorship rate is equal at all stages of life
3. very high birth rate, very high infant mortality rate

8. Survivorship in a developing country.

9. Survivorship of a developed country.

10. Changes in a population’s size are determined by immigration, births, emigration, and deaths.
The size of a population is always changing.
Four factors affect the size of a population.
Immigration, moving in
births
Emigration, moving out
deaths

11. Population growth is based on available resources.
Exponential growth is a rapid population increase due to an abundance of resources.

12. Logistic growth is due to a population facing limited resources.

13. Carrying capacity is the maximum number of individuals in a population that the environment can support.
A population crash is a dramatic decline in the size of a population over a short period of time.

14. Ecological factors limit population growth.
A limiting factor is something that keeps the size of a population down.
Density-dependent limiting factors are affected by the number of individuals in a given area.

15. Density-dependent limiting factors are affected by the number of individuals in a given area.
parasitism and disease
predation
competition

16. Density-independent limiting factors limit a population’s growth regardless of the density.
unusual weather
natural disasters
human activities

17. Succession occurs following a disturbance in an ecosystem.
Succession regenerates or creates a community after a disturbance.
a sequence of biotic changes
damaged communities are regenerated
new communities arise in previously uninhabited areas

18. There are two types of succession.
primary succession — establishment and development of an ecosystem in an area that was previously uninhabited
started by pioneer species

19. There are two types of succession.
secondary succession — reestablishment of a damaged ecosystem where the soil was left intact
started by remaining species

20. The biosphere is the portion of Earth that is inhabited by life.
The biosphere includes all ecosystems.
one of Earth’s systems
includes the biota, all the living things in the biosphere

21. Climate is the prevailing weather of a region.
Climate is the long-term pattern of weather conditions.
average temperature
precipitation
relative humidity

22. A microclimate is the climate of a small specific place within a larger area.

23. Mountains have an effect on climate.
Precipitation occurs on the side of the mountain facing the wind.
On the downwind side, drier and cooler air produce a rain shadow.
A rain shadow is an area of decreased precipitation.
western slope
eastern slope

24. Earth has three main climate zones.
The three main zones are the polar, tropical, and temperate climates.
polar climate: the far northern and southern regions of Earth
temperate zone: the wide area in between the polar and tropical zones
tropical zone: surrounds the equator
The angle of the sun’s rays
create these climate zones.

25. Key factors influence an area’s climate.
temperature
sunlight
Water and wind movement
landmasses
Earth’s tilt on its axis plays a role in seasonal change.
Solar heating causes movements in both water and air.
wind
ocean currents
Earth’s rotation also has effects on the winds and currents