Transcript Percentage of Population

Chapter 5 –Populations
Chapter 6 –Humans In the Biosphere
I. Characteristics of Populations
A. Geographic distribution - (range) area inhabited by
a population
B. Population density-number of individuals per unit area
ex: 200 people/ km2
C. Growth rate- increase or decrease of number of
individuals in a population over time.
II. 3 Factors that Affect Population Size
A. number of births
B. number of deaths
C. number of individuals entering (into- immigration)
or leaving (exiting- emigration) a population
D. Population grows when birthrate is greater
than deathrate.
III. Exponential growth - when the individuals in a population
reproduce at a constant rate.
A. Population becomes larger and larger until it approaches an
infinitely large size.
B. Under ideal conditions with unlimited resources, a population
would grow exponentially (J-shaped curve)
IV. Logistic Growth - when growth slows or stops following a
period of exponential growth (S-shaped curve)
A. carrying capacity (K)- largest # of individuals of a population
that an environment can support
B. Growth levels off, so the average growth rate is zero.
V. Limiting factor -factor that causes population growth
to decrease
A. Density-dependent limiting factor - limiting factor
that depends on pop. size
1. Ex: competition, predation, parasitism, disease, crowding
2. Has greatest influence when pop. is large & dense; does
not affect small, scattered pop. as greatly
3. Competition- when pops. become crowded, they
compete for food, water, space, sunlight, other resources
4. Predation- regulation of a pop. by predation is a
predator-prey relationship
Wolf and Moose Populations on Isle Royale
B. Density-independent limiting factors -affect all
pops in similar ways, regardless of the pop. size.
1. Ex. weather, drought/floods, fire, human activity
(clear-cutting, damming rivers, development)
5-3
VI. Human Populations
A. Began growing more rapidly due to advances in
agriculture and industry.
B. Death rates- reduced due to improved sanitation,
medicine, healthcare, while birthrates remained
high.
5-3
Human Population Growth
C. Demography-study of human population growth
1. past century- pop. growth in US, Japan, Europe has slowed
2. Demographic Transition, a huge change in birth and death
rates.
5-3
D. 3 stages of Dem. Trans:
1. Stage 1- high birthrate;
high death rate
2. Stage 2- birthrate high;
death rate drops
3. Stage 3-birthrate
drops; pop growth
slows
5-3
E. Age-structure diagram –
shows the pop. of a country
broken down by gender and
age group; can predict future
growth of pop.
U.S. Population
1. US- nearly equal no. of
people in each age group
2. predicts a slow but steady
growth rate for the near
future
Percentage of Population
5-3
Rwandan Population
3. Rwanda- many more
children/ teenagers, than
adults.
4. diagram predicts pop.
will double in about 30
years
Percentage of Population
5-3
F. To predict human pop. growth, demographers must
consider age structure and disease.
1. If growth does
not slow damage
to the environment
and global
economy.
2. Science,
technology, &
changes in society
may limit the
negative impact of
population growth.
6-1
I. Human activities affect the biosphere.
A. Hunting-gathering- isolated parts of the world
B. Agriculture -Irrigation, fertilizers, pesticides
C. Industrial Revolution to Present
1. Increased pollution of air, water, soil by fossil fuels
2. Increased human waste and increased development
places stress on native plants/ animals; consumes farmland
D. Pollution  contamination of soil, water, or air
1. has increased as countries become industrialized
2. Pollutant - harmful material that can enter the biosphere
through the land, air, or water
3. Air Pollution caused by burning of fossil fuels that
release pollutants that cause smog
a. example: driving cars, flying planes, heating homes,
factories
b. example of air pollutants  dust, smoke, ash, CO,
sulfur oxides
-Strict emissions and clean-air regulations have improved air
quality
c. Causes Acid rain- sulfuric acid/nitric acid from the burning
of fossil fuels mix with water vapor forming low pH rain
(car exhaust = nitric acid; coal-burning factories = sulfuric acid)
*Acid rain damages plants, kills aquatic organisms, erodes
buildings and monuments, depletes soil of nutrients
Emissions to
Atmosphere
Nitrogen oxides
Sulfur dioxide
Industry
Condensation
Chemical Transformation
Nitric acid
Sulfuric acid
Ore
Transportation
smelting
Dry Fallout
Particulates Precipitation
Gases
Acid rain, fog,
snow, and mist
Power
generation
d. Burning fossil fuels releases Carbon Dioxide into the
atmosphere.
- Excess CO2 can contribute to the greenhouse effect 
thought to be the cause of global warming
e. Global warming- cycle or human activity ?- CO2 levels
have increased over past 200 yrs-intensifies greenhouse
effect
Page 87
f. Greenhouse Effect
Some heat
escapes
into space
*Atmospheric gases
that trap the heat energy
of sunlight and maintain
Earth's temperature
range include:
Greenhouse
gases trap
some heat
•carbon dioxide
•methane
Atmosphere
•water vapor
Earth’s Surface
g. Monitor ozone layer and global climate system
1. Ozone layer- O3-protects Earth from UV radiation
can cause cancer, eye disease, tissue damage in plants
2. CFC’s (Chlorofluorocarbons) destroys ozone layer
*found in aerosols and coolants
* have been reduced
4. Water Pollution  caused by contaminants from sewers,
industries, farms, and homes that enter lakes, rivers,
groundwater and oceans
*Sewage, chemical waste, fertilizer, and dirty wash water
enter the water systems
Terracing
Contour Plowing
II. Renewable and nonrenewable resources
A. Renewable resources (rnr)- can regenerate (if living)
or be recycled (if part of biogeochemical cycles)
Ex: trees, water
B. Nonrenewable resourcescannot be replenished by natural processes, are in
limited amounts, once they are gone – they are gone!!
Ex. Fossil fuels such as coal and oil, gold, silver, copper
C. Renewable or nonrenewable?
1. Depends on if the loss is large enough to change an
ecosystem forever ex: coral reefs
2. ex: single tree=renewable resource, but an entire pop.
of trees may change the entire ecosystem
III. Biodiversity-sum total of the genetically
based variety of all organisms in the biosphere
Three types of diversity in ecosystems:
A. Ecosystem diversity-variety of habitats,
communities, and ecological processes in the
living world.
B. Species diversity is the # of different species in
biosphere; increases moving towards equator.
C. Genetic diversity is the sum total of all the
different forms of genetic information carried by all
organisms living on Earth today.
IV. Importance of Biodiversity
A. Plants and some animals produce compounds
that are beneficial
B. food, industry, medical- painkillers, antibiotics,
antidepressants ;cancer/heart drugs/ high blood
pressure ex: rosy periwinkle and digitalis
Rosy periwinkle

digitalis
Foxglove
V. Threats to Biodiversity
1. Loss of habitat- degradation (damage by pollution);
fragmentation (split into pieces)
2. Hunting- food, fur,pets (birds), poaching
3. Introduced species- may become invasive species (lack
predators from homeland); wipe-out native pops.
Ex: zebra mussels,leafy spurge, goats
Leafy spurge
Zebra mussel
This plant is an invasive, deep-rooted
perennial herb that is native to Eurasia;
plant spreads through explosive seed
release and vigorous lateral root growth,
forming large, patches that can
dominate rangeland, pastures, prairies
and other areas in the Great Plains
region of North America, killing native
plant species.
Zebra mussels can attach to native
mussels, killing them. Zebra
mussels filter plankton from the
surrounding water. This filtering
can increase water clarity, which
might cause more aquatic
vegetation to grow at deeper
depths and more dense stands. If a
lake has high numbers of mussels
over large areas, this filter feeding
could impact the food chain,
reducing food for larval fish.
4. Pollution  DDT-softened shells of
birds eggs - osprey, brown pelican, eagle
population threatened
a. Rachel Carson- 1962 Silent Springbook about dangers of biological
magnification
b. Biological magnification–
concentration of harmful
substances increase at higher
trophic levels; DDT banned US1970’s
VI. Conservation- management of resources, habitats,
and wildlife
1. US Endangered Species Act-1973-illegal to harm
endangered or threatened species
2. Expand National Parks or “green space” in cities
3. Habitat corridors-strips of land that allow migration
4. Reintroduction programs- breed animals, then
release back into wild
5. Identify global “hot spots”-(organisms are in danger of
extinction due to human activity); work on protecting those
habitats; often endemic species (found no where else in the
world!!)
5-1
–
Population density is the number
of individuals
A. that are born each year.
B. per unit area.
C. that immigrate.
D. that emigrate.
5-1
–When the birthrate of a population
exceeds its death rate, the
population
A. decreases.
B. increases.
C. stays the same.
D. increases then decreases.
5-1
–An S-shaped curve on a graph of
population growth is characteristic
of
A. exponential growth.
B. logistic growth.
C. carrying capacity.
D. delayed growth.
5-1
– Exponential growth in a population
slows down or stops as
A. resources become limited.
B. rate of immigration increases.
C. rate of emigration decreases.
D. birth rate increases.
5-1
–Exponential growth rate means that each
new generation of a population
A. adds the same number of new
individuals as the previous generation
did.
B. increases at the same rate as the
previous generation
C. is the same size as the generation
before.
D. increases by a varying amount.
5-2
– A limiting factor that affects all
populations in similar ways
regardless of their size might be
A. drought.
B. disease.
C. predation.
D. crowding.
5-2
–Which of the following would be a
limiting factor directly affecting the
panda population of China?
A. programs that educate people
about endangered species
B. capture of some pandas for
placement in zoos
C. laws protecting habitat
destruction
D. a disease that kills bamboo plants
5-2
–Density-dependent factors
operate most strongly when a
population is
A. large and dense.
B. large but sparse.
C. small and sparse.
D. small, but growing.
5-2
–Within a limited area, if the
population of a predator
increases, the population of its
prey is likely to
A. increase.
B. decrease.
C. remain about the same.
D. become extinct.
5-2
–Which of the following is a
density-independent factor
affecting populations?
A. predation
B. disease
C. a destructive hurricane
D. parasites
5-3
–The size of the human population
began to increase exponentially
after the
A. bubonic plague.
B. development of plowing and
irrigation.
C. Industrial Revolution.
D. development of the first
cities.
5-3
–Which of the following is NOT a
potential limiting factor of
human population growth?
A. famine
B. medicine
C. war
D. disease
5-3
–After the demographic transition
is complete, a population
A. grows rapidly.
B. grows slowly.
C. begins a period of rapid
decline.
D. stays about the same size as
time passes.
5-3
–An age-structure diagram shows
a breakdown of a population by
A. location and age group.
B. age group and gender.
C. birthrate and death rate.
D. age group and emigration
rate.
5-3
–Since the mid-1960s, the average
annual growth rate of the human
population has
A. remained about the same.
B. failed to show a consistent
pattern.
C. increased.
D. decreased.