Download Unit: Interactions Among Organisms Sections: Energy in Ecosystems

Unit: Interactions Among Organisms
Sections: Energy in Ecosystems, Overpopulation
Key Words: ecosystem, energy, food web, food chain, energy pyramid, carrying capacity, overpopulation, limiting
factors
Essential Questions:
Energy in Ecosystems
-
How does energy flow through ecosystems?
Why is food important to organisms?
Why are all organisms connected to each other?
Overpopulation
-
Why does overpopulation occur?
What problems does overpopulation cause?
How can overpopulation be reduced?
Energy in Ecosystems
Food Web
-
An interconnected network in an ecosystem
Transfer of energy occurs
Involves biotic and abiotic factors
Affect one organism in the web, affect them all
Food is necessary for survival
o Growth and development (assimulation)
o Energy for all cellular processes
Law of Thermodynamics
0th Law (Zeroth)
If 2 systems are in
equilibrium with a 3rd
system, then they are in
equilibrium with each other
Refers to temperature
1st Law
2nd Law
3rd Law
Law of conservation of
energy
An isolated system, if not
already in a state of
equilibrium, will evolve
towards it
The entropy (disorder) of a
system approaches a
constant value as the
temperature approaches
zero
energy cannot be created
nor destroyed, only
transferred
Entropy - measure of how
close a system is to
equilibrium, or a measure of
the disorder in the system
Cannot ever reach absolute
zero but can "arbitrarily"
approach it
heat and work are forms of
energy transfer
-
-
Thermodynamic system
o Consists of a pure substance can be described as a collection of like molecules, each with its
individual motion is describable in terms of velocity and momentum
Calorie measurement
o 1 calorie = the amount of heat energy required to raise 1 g of H2O up 1° Celsius (~4.19 J)
Overpopulation
Populations in an ecosystem
-
Quantity of the types of species in an ecosystem
More diversity, more healthy and stable
Delicate balance between cooperative and competitive relationships
Depend upon resources to survive
o Abiotic factors
o Biotic factors
o Can be limited
Limiting
Resources
water
-
food
shelter
Any fluctuation of the limiting resources will affect the population
o Increase
 Considered overpopulation
 Some environments can handle the increase
 Others cannot – considered overpopulation
o Decrease
 Available resources shared
 Makes it more difficult for other species to survive
o End result
 Drastic number loss of overpopulated species
 Dies out completely
Due to famine (starvation)
Due to disease
o Carrying capacity
 The idea numbers of populations that an ecosystem can support based upon its resources
available