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biology ch 36
population and community
48
Science
9th Grade
05/03/2016

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Term
What is a population?
Definition
a group of organisms of the same species that live in a particular area
Term
What is growth rate?
Definition
= change in number of individuals
__________________________________
time period
Term
What factors play a role in an area's growth rate?
Definition
birth rage, immigration, death rate and emigration
Term
What is the difference between immigration and emigration?
Definition
immigration - movement of organisms into an area

Emigration - movement of organisms out of an area
Term
Explain what the age structure of a population means.
Definition
Age structure means the proportion of individuals in a population that are young, old and in between
Term
How do scientists use an area's age structure to make predictions about changes in a population?
Definition
Determines future needs for communities
Term
What is exponential growth?
Definition
Occurs when the rate of population in each new generation doubles itself
Term
What is the difference between abiotic and biotic resources?
Definition
Abiotic - Nonliving part of an environment, such as water, soil, light, temperature and wind

Biotic - living part of an environment, such as a plant, animal or other organisms
Term
What is a limiting factor?
Definition
Any biotic or abiotic resource in the environment that limits the size of a population

Examle: land, waer, food, sunshine
Term
Define: Carrying Capacity
Definition
It is the number of individuals in a population that an environment can support over a relatively long period of time
Term
What causes populations to increase?
Definition
Lots of food, low diseases, lots of water, few predators, good shelter
Term
What causes populations to decrease?
Definition
Low amount of food, high disease, low water, lots of predators, poor shelter
Term
How do limiting factors in the environment keep the population size in check?
Definition
Either cause a decrease in the birth rate or an increase in the death rate
Term
Define: Density dependent limiting factors
Definition
Only become limiting when the population density - the number of organisms per unit of space reaches a certain level
Term
What are some density dependent limiting gators?
Definition
living space, disease, competition, predation
Term
What is density - independent limiting factors?
Definition
Factor that affects all populations regardless of their population density
Term
What are some density independent limiting factors?
Definition
Weather, seasonal cycles, natural disasters
Term
What has happened to the Earth's human population over time?
Definition
Was slow - now the population doubling time is getting shorter and shorter. Scientists estimate population grows 90 million people every year
Term
Why are ecologists concerned about Earth's increasing population?
Definition
Huge demand on natural resources, food, space, etc.
Term
What is a community?
Definition
A collection of populations that interact with each other in a given area
Term
What are the levels of organization?
Definition
organism
population
community
ecosystem
Term
What are invasive species?
Definition
Nonnative plants and animals (not original to an area)
Invasive means.. invader
Term
What are some invasive species in Michigan?
Definition
Asian carp
round goby
purple loosestrife
feral pigs
sea lamprey
zebra mussels
mute swan
Term
Why are invasive species bad for our environment?
Definition
* No predators to kill them
* pose a threat to our ecosystems
* hard to get rid of
Term
How do invasive species come to Michigan?
Definition
intentionally and accidentally
Term
How are invasive species managed?
Definition
new laws
Term
What is the main cause for invasive species spreading so quickly?
Definition
humans
Term
How do the different populations interact with each other?
Definition
compete for resources - food, water, shelter, etc.
Prey on one another
Term
What is a niche?
Definition
a particular role that a population plays in its community
Term
What is a habitat?
Definition
the natural home or environment of an animal, plant or other organism
Term
What is a predator?
Definition
An organism that eats other organisms
Term
What is prey?
Definition
An organism eaten by another organism
Term
Define: Symbiosis
Definition
When one species lives in close association with another species over a period of time
Term
What is mutualism?
Definition
2 species interact closely in a way that benefits both species
Term
What is parasitism?
Definition
Where one species benefits and the other is harmed
Term
What is commensalism?
Definition
one organism benefits from the relationship and the other organism in NOT helped or harmed
Term
Why is genetic diversity within populations important in maintaining ecological balance in a community?
Definition
A population with high genetic diversity will survive because their genetic make up makes them more resistant to disease
Term
What is ecological succession?
Definition
A change in the community resulting in new populations of organisms gradually replacing existing ones
Term
What is primary succession?
Definition
A process that occurs when a new community arises from a previously lifeless habitat
Begins with bare land - NO soil is present
Term
What are lichens?
Definition
One of the first plants to get established in a pioneer community
They release a weak acid to help break down rock and trees, etc.
Term
What is a pioneer community?
Definition
The first organisms to occupy an area previously uninhabited by its species
Term
What is a climax community?
Definition
An established community that encounters little ecological succession
* Has reached stability
Term
Define - Secondary succession
Definition
The development of a new community in a previously occupied habitat
* already begins with soil
Term
What is aquatic succession?
Definition
Water fills in a pond to make it a land ecosystem
Term
What is eutrophication?
Definition
A process of a body of water becoming nutrient rich
Term
What are the main sources of eutrophication?
Definition
sewage plans, agriculture run off, fertilizers
Term
What are the main chemicals that cause eutrophication?
Definition
Nitrogen and phosphorus
Term
Secondary succession occurs faster than primary succession - T or F
Definition
True
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