PROPERTIES OF POPULATIONS:
A-Size: is the total number of individuals.
4 variables can limit the size of a population:
1. The number of deaths
2. The number of births
3. Immigration
4. emigration
The change in a population from high birth and death rates to low birth and death
rates is known as Demographic transition.
Biological magnification:
Organisms occupying higher trophic levels have greater concentration of accumulated toxins stored in
their bodies than those at lower trophic levels
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B- Density: Density is the number of individuals per unit area or volume.
C-Dispersion is the pattern of spacing of individuals within the area the population
inhabits.
D- Age distribution
Remember
 Biotic potential: the maximum rate at which a population could increase
under ideal conditions.
 Limiting factors are those factors that limit population growth. They are
divided into two categories:
A-Density-dependent factors are those factors that increase directly as the
population density increases. They include:
1-competition for food
3-Predation
2- Buildup of wastes.
4-Disease
B-Density-independent factors are those factors whose occurrence is unrelated to
the population density. They include:
1- Earthquakes
2- Storms.
3- Naturally occurring fires and floods.
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Types of population growth:
Carrying Capacity:
A limit to the number of individuals that can occupy one area at a particular time.
(K).
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Biomes
Aquatic biome
Marine biome: sea , ocean (the largest and most stable biome)
 Ocean provides most oxygen (highest diversity).
 Fresh water biome: rivers and streams move in one direction.
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Terrestrial biomes
Biome
Tundra
(permafrost)
Characteristics
Organisms
Bear , caribou , birds
-Located in the far northern parts of north and shrubs
America, Europe, and Asia
-permanently frozen subsoil found in the
farthest point
north, including Alaska
caribou, polar bears
-Though the number of individual
organisms in the tundra is high,
the number of species is small
Taiga -Conifer forest Dominated by conifer (evergreens)
forests
• Has very cold winters The taiga—
the conifer forest– is the largest
terrestrial biome.
It is also called boreal forest.
Tropical rain forest The tropical rain forest has the
greatest diversity of animal species
of any biome.
large mammals
including black bear
and elk and conifer
trees
Reptiles insects
High precipitations
stable temperatures, and high
humidity.
Covers less than 4 percent of Earth’s
land surface but produces 20 percent
of Earth’s food.(high productivity)
Rapidly decreasing due to human
interaction.
Deciduous forest
Contain trees that shed their leaves
during the cold winter months as
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Squirrel ,
Bear. maples, oak.
Savanna
Desert
Plentiful grasses, few trees
Long dry winter and very wet
summer.
It is characterized by extreme daily
temperature changes.
Elephant
girrafe
cactus,snakes,
lizards.
Daytime temperature may reach as high as
70C ; heat is lost rapidly at night
Chaparral
Temperate
grassland
Dry land.
Shrub land ,fires occur.
Contain most human food resource.
Acid rain
Acid rain is caused by pollutants in the air from the combustion of fossil fuels.
Nitrogen and sulfur pollutants in the air turn into nitric, nitrous, sulfurous, and
sulfuric acids, which cause the pH of the rain to be less than 5.6. This causes the
death of the organisms in lakes and damages ancient stone architecture.
SO2+H2O
H2so4
No2+H2o
HNO3
Sulphuric acid
Nitric acid
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EUTROPHICATION
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