Download Chapter 2.2 – Flow of Energy in an Ecosystem

Chapter 2.2 – Flow of Energy in
an Ecosystem
Chapter 2
Principles of Ecology
2.2 Flow of Energy in an Ecosystem
Energy in an Ecosystem
 Autotrophs
 Organism that collects energy from sunlight
or inorganic substances to produce food
 Heterotrophs
 Organism that
gets it energy
requirements by
consuming other organisms
A lynx is a heterotroph.
Chapter 2
Principles of Ecology
2.2 Flow of Energy in an Ecosystem
 Detritivores eat fragments of dead matter in
an ecosystem, and return nutrients to the
soil, air, and water where the nutrients can
be reused by organisms.
Fungus
Chapter 2
Principles of Ecology
2.2 Flow of Energy in an Ecosystem
Models of Energy Flow
 Food chains and food webs model the
energy flow through an ecosystem.
 Each step in a food chain or food web is
called a trophic level.
Chapter 2
Principles of Ecology
2.2 Flow of Energy in an Ecosystem
Food Chains
 A food chain is a
simple model that
shows how energy
flows through an
ecosystem.
Level 4 Tertiary consumer
Food chains
 Feeding relationships
Top
carnivore
Level 3 Secondary consumer
all food chains
start with energy from
Carnivore
the sun
Level 2 Primary consumer
 first level of all food
chains is plants
Herbivore
 most food chains Level 1 Producer
usually go up
only 4 or 5 levels
 all levels connect to
Decomposers
decomposers
Bacteria

Regents Biology
Sun
Fungi
Food Chains in the water too.
Regents Biology
Chapter 2
Principles of Ecology
2.2 Flow of Energy in an Ecosystem
Food Webs
 A food web is a
model representing
the many
interconnected food
chains and pathways
in which energy flows
through a group of
organisms.
But what about decomposers?
 Energy flows through
but nutrients cycle

nutrients must be
recycled to be available
for the next generation

decomposers return
nutrients to the soil
after creatures die
 fungi
 bacteria
Regents Biology
n
u
t
r
i
e
n
t
s
decomposers
Chapter 2
Principles of Ecology
2.2 Flow of Energy in an Ecosystem
Ecological Pyramids
 A diagram that can show the relative
amounts of energy, biomass, or numbers of
organisms at each trophic level in an
organism
Food chain pyramid
 Loss of energy between levels of food
chain

can feed fewer animals in each level
Numbers
1
100
100,000
1,000,000,000
Regents Biology
Vegetarians or Meat-eaters??
 How many people can Earth support?
If we are meat eaters?
 If we are vegetarian?

more people can
live on Earth
Regents Biology
fewer people can
live on Earth