Ecology and People (BIOL 120)
Defining Matter and Energy
Lecture 2: Matter and Energy: flows and cycles
Today’s Outline
Announcements
! Defining Matter and Energy
! Capturing and using energy
(photosynthesis and respiration)
! Matter and energy flows through
ecosystems
(trophic levels & food webs)
!The Carbon Cycle
!The Hydrologic Cycle
Capturing and Using Energy
Energy:
The ability to do work such as moving matter
over a distance or causing a heat transfer
between two objects
2 types:
" Kinetic
" Potential
#Chemical
Matter:
Everything that takes up space and has mass
Energy:
The ability to do work such as moving matter
over a distance or causing a heat transfer
between two objects
Thermodynamics
# Energy must be supplied from an external source to
keep biological processes running.
" Energy flows in a one-way path through living systems and
into a temperature sink.
# First Law of Thermodynamics - Energy is neither
created nor destroyed.
# Second Law of Thermodynamics - With each
successive energy transfer, less energy is available
to perform work.
Photosynthesis
Capturing and Using Energy
Capturing the Sun’s Energy
"Photosynthesis
Using Energy
"Respiration
Enger & Smith 2005
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Connections:
Energy Flow in Ecosystems
Respiration
$Food chains
Z
Z
C
B
Y
A
Enger & Smith 2005
Trophic Levels
Trophic Level - Expression of an organism’s
feeding status in an ecosystem.
Producers (plants)
Consumers
Primary, Secondary, Tertiary
Most terrestrial food chains relatively short.
Aquatic food chains tend to be longer.
Trophic Levels
Y
$Food webs
X
X
Trophic Levels
! Primary consumer (herbivore)
! Secondary consumer (carnivore)
! Tertiary consumer
! Omnivore
! Detritivores and scavengers
! Decomposers
Connections: Food Chains and Energy Flow
in Ecosystems
Trophic Levels
Sun
Producers (rooted plants)
Producers (phytoplankton)
Primary consumers (zooplankton)
Secondary consumers (fish)
Tertiary consumers
(turtles)
Decomposers (bacteria and fungi)
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Food Web
Ecological Pyramids
Due to Second Law of Thermodynamics, food
chains often form an inverted pyramid.
Metabolism
Predator efficiency < 100%
10% Rule (Energy / Biomass)
100 kg clover
10 kg rabbit
1 kg fox
Second Law of Thermodynamics - With each successive energy transfer,
less energy is available to perform work.
Energy Pyramids
The Carbon Cycle
Hydrologic (Water) Cycle
Autotrophic
Heterotrophic
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