3-2: Energy Flow
Biology 1
Introduction
• Every organism needs energy to
power its life’s processes
• The flow of energy through an
ecosystem is one of the most
important factors that
determines the system’s
capacity to sustain life
Producers
• Sunlight is the main source of
energy for life on Earth
– Some organisms can use energy
stored in chemical compounds
• AUTOTROPH: organism that can
capture energy from sunlight or
chemicals and use it to produce
its own food from inorganic
compounds; also called a
producer
– Only plants, algae and some
bacteria are autotrophs
Producers
• Because autotrophs can make
their own food, they are also
called producer
• PRODUCER: organism that can
capture energy from sunlight or
chemicals and use it to produce
food from inorganic
compounds; also called an
autotroph
Consumer
• Many organisms cannot take
energy from sunlight like
autotrophs do
• HETEROTROPH: organism that
obtains energy from the foods
it consumes; also called a
consumer
Producers
• Because heterotrophs have to
“eat” other organisms for
energy, they are also called
consumers
• CONSUMER: organism that
relies on other organisms for
its energy and food supply;
also called a heterotroph
– Animals, fungi and bacteria
Consumers
• There are 5 different types of
heterotrophs (consumers):
– HERBIVORE: organism that obtains
energy by eating only plants
– CARNIVORE: organism that obtains
energy by eating animals
– OMNIVORE: organism that obtains
energy by eating both plants and
animals
– DETRITIVORE: organism that feeds on
plant and animal remains and other
dead matter
– DECOMPOSER: organism that breaks
down and obtains energy from dead
organic matter
Feeding
Relationships
• Energy flows in 1 direction
through ecosystems
( Sun  Autotroph  Consumer )
• FOOD CHAIN: series of steps in
an ecosystem in which
organisms transfer energy by
eating and being eaten
– Food Chains show you who gets
eaten!
Feeding
Relationships
• FOOD WEB: network of
complex interactions formed
by the feeding relationships
among the various organisms
in an ecosystem
– Usually more than one type of
organism that gets eaten, food
webs show you everything!
• TROPHIC LEVEL: step in a food
chain or food web
– Every arrow shows you a new
trophic level!
Section Assessment
1. The flow of energy through an ecosystem is
one of the most important factors that
___________ .
2. Autotrophs (producers) can ___________ .
3. Heterotrophs (consumers) have to
___________ .
4. What are the 5 different types of consumers?
5. Energy flows in ___________ .
6. What is the difference between food chains
and food webs?
3-2: Energy Flow
-- Use your notes and the book to
complete 3-2 Lesson Review
worksheet
-- When finished please turn in