KEY
Unit 6: Population & Biodiversity STUDY GUIDE
You can write on this sheet or on another sheet of paper. FILL IN THE FOLLOWING BLANKS WITH THE
PROPER DEFINITION and/or DESCRIPTION:
1. Populations can be described in terms of three things:
a. Population size = number of total individual in a population (all members of the same species living in the
same area)
b. Population density = number of individuals per unit area
c.
Population dispersion = distribution of individuals within a given space: The 3 types of dispersion
are (provide definition & example):
i. Random = random placement; Ex: seen in some plants
ii. Uniform = evenly spaced – helps reduce competition; Ex: sea turtles nesting, cacti in desert
iii. Clumped = small, close groups – helps in defense & reproduction; Ex: herds, packs, flocks
2. Growth rate = change in pop size over time; (B + I) – (D + E)
a. Occurs when new individuals are added by birth or immigration
Or when individuals are lost due to death or emigration
3. Reproductive potential = max number of offspring that an individual can produce
a. High reproductive potential is seen in organisms like: bacteria, insects, rodents, protists, clams, frogs, etc.
4. The two kinds of population growth are:
a. Exponential growth; J-shaped
i. Defined as: rapid, continuous growth
ii. Occurs when there’s plenty of resources, little competition and predation
b. Logistic growth; S - shaped
i. Defined as: rapid growth followed by leveling off at carrying capacity
ii. Occurs when the population levels off at carrying capacity
5. Carrying capacity = maximum number of individuals an ecosystem can support
6. Factors that limit population growth are:
a. Density-dependent factors (related to pop size)
i. Examples: limited resources, disease, predation
b. Density-independent factors (control pop regardless of size)
i. Examples: natural disasters, humans – habitat destruction, pollution, etc.
7. There are 2 kinds of organisms with respect to population growth:
a. r-selected organisms = organisms with high reproductive rate to balance high death rate of offspring
i. Examples: frogs, insects, clams, small mammals
b. k-selected organisms = organisms that have a longer generation time, late sexual maturity, & fewer young
i. Examples: elephants, whales, birds, large mammals, humans
8. Demography = study of human populations
9. Developed countries examples: USA, Canada, Australia, Japan, England, France, Italy, Germany, etc.
a. Have HIGH or LOW birth rate? LOW
10. Developing countries examples: Mexico, China, India, Haiti, Jamaica, Egypt, Peru, etc.
a. Have HIGH or LOW birth rate? HIGH
11. Properties used to predict future population changes:
a. Doubling time = time it takes for a pop growing at a specific rate to double its size
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b. Fertility rate = number of babies born each year per 1,000 women; high in developing countries
c. Migration = movement into an area
d. Age structure = distribution of ages in a country
i. Developing countries’ age structure diagrams look like pyramid/ triangle
ii. Developed countries’ age structure diagrams look like rectangles; more even among age classes
Demographic Transition = model that shows the effects of economic and social changes on a population’s birth
and death rates
Current human population ~ 7 billion
a. What affects a country’s population growth:
i. Type of economy
ii. Status of WOMEN
iii. Cultural beliefs such as the importance of sons
iv. Religious beliefs
b. Problems with human population growth include (name at least 5 problems):
i. Resource depletion, esp. nonrenewable resources
ii. Water & air pollution
iii. Loss of farmable land
iv. Loss of biodiversity
v. Diseases
c. Ways governments slow down population growth: advertising, family planning programs, economic
incentives, legal punishments. Ex: China’s One-Child Policy; Thailand’s funny commercials
Biodiversity: Number of species on Earth is estimated to be 10 million; actual number known is 1.7 million
Biodiversity can be studied at three levels:
a. Species diversity = number of different species in an area
b. Ecosystem diversity = variety of habitats, communities, and ecological processes in an ecosystem
c. Genetic diversity = all the different genes contained within the population’s gene pool
Why is biodiversity important? (1) W dependent on healthy ecosystems to ensure balanced nutrient cycles; (2) we
use a variety of organisms for food, clothing, shelter & medicine; (3) bioethics – some believe it’s the moral thing
to do to save organisms; (4) aesthetic value & personal enjoyment
High biodiversity can be found in tropical rain forests, coral reefs, coastal areas, and islands
Biodiversity hotspots = have high numbers of endemic species and are threatened by humans
a. Endemic species = species found only within a limited area
Endangered species = species in immediate danger of extinction
Threatened species = species who’s populations are declining
Threats to biodiversity include:
a. Habitat fragmentation and destruction
b. pollution
c. invasive species – not native to an area and causing problems
d. overharvesting
Solutions to the loss of biodiversity include:
a. Captive breeding programs and zoos
b. Important Law: Endangered Species Act of 1973
c. IUCN stands for: International Union for the Conservation of Nature and Natural Resources
d. CITES stands for: Convention on International Trade in Endangered Species