Energy Flow Through Trophic Levels
Biology 12(C)
Energy
• Originates from sun
• Transferred between organisms
• Leaves ecosystem as motion and heat
Biotic & Abiotic Factors
• Biotic factors – the living components of the environment
EX:
• Abiotic factors – the nonliving components of the environ
EX:
Autotrophs & Heterotrophs
• Heterotroph – organism that must acquire energy by
consuming other organisms
• Autotroph – organism that is able to capture energy from
the sun to make it’s own food
ATP (Adenine Tri Phospate)
• Organisms use chemical energy from food
• Breaking down carbohydrate bonds releases energy
• Stored in Bonds of (ATP)
• Draw in notebook ATP
Energy Flow Through Trophic Levels
Organisms survive by:
• Producing food or feeding on other organisms
Flow of matter and energy:
• Organisms eat each other to get energy (except plants)
• Instead of saying “bear eats fish” we say
“the energy in the fish is transferred to the bear”
Trophic Levels
Trophic level – distinct level of feeding within ecosystem
• Species at each level vary in different communities
Trophic levels:
• Producer
• Consumer
– Primary
– Secondary
– Tertiary (or top)
• Decomposer
Trophic Levels
Producer – produce own
food, first or lowest
trophic level
• Example: plants
Primary consumer – firstorder consumer, eats a
producer
• Example: grasshopper
Trophic Levels
Primary consumer –
first-order consumer,
eats a producer
• Example: grasshopper
Secondary consumer –
second-order consumer,
eats primary consumer
• Example: lizard
Trophic Levels
Secondary consumer –
second-order consumer,
eats primary consumer
• Example: lizard
Tertiary consumer – thirdorder consumer, eats
secondary consumer
• Example: snake
Trophic Levels
Decomposer (saprobe) – breaks down dead plant and animal
matter and returns nutrients to soil
– Examples: bacteria and fungi
You will have a quiz in 5 minutes….STUDY!
Trophic Energy Quiz 1 (10pts)
• On a separate sheet of paper answer the following:
1. What are biotic factors and list 2
2. What are abiotic factors and list 2
3. What does this picture show?
4. Make a pyramid and divide it into half (a top half and a
bottom half). Places the words “producer” and “consumer”
into the part of the pyramid where they apply to and define
each next to the word in the pyramid.
Trophic Levels
Sometimes consumers are referred to by type of food they
eat rather than trophic level:
• Herbivore – eats only plants
– Examples: deer, rabbit
• Carnivore – eats only animals
– Examples: lion, shark
• Omnivore – eats plants and animals
– Examples: bear, human
• Scavenger – feed only on dead organisms
– Examples: vulture, hyena
Food Chains
Food chain – sequence of organisms feeding on one another
at a lower trophic level
Producer
Primary Consumer
Secondary Consumer
• In this food chain, which is the …
Producer1* Primary Consumer2* Primary Consumer3* Primary Consumer4* Primary Consumer-
Food Webs
Food web – network of interacting food chains
• Most organisms eat more than one food type
• Ecosystems usually contain more than one food chain
• Complex relationships between trophic levels
•
•
Highlight 4 different food chains and put them in order of Producer, 1 C, 2 C, 3 C, 4 C ,
….
What do they have in common, different, are any organisms on two different trophic levels?
You will have a quiz in 5 minutes….STUDY!
Trophic Energy Quiz 2 (20pts)
• On a separate sheet of paper answer the following:
1. Define and give an example for:
- producer
- herbivore
- carnivore
- omnivore
- scavenger
- decomposer
2. Copy the food web at right and label each organism as one
of the above based only on the data in the food web.
Food Webs
• Which organisms are the
producers?
– Pond weed and algae
• Which organisms are the
secondary consumers?
– Perch, minnow, and
dragonfly
• Which organisms do
frogs eat?
– Minnow and dragonfly
Complex Food Web
Food Webs
•
•
Which consumers feed on bivalves?
– Sea ducks, tundra swans, and herbivorous ducks
Which consumers feed on zooplankton?
– Small fish, bivalves
Ecological Pyramids
Ecological pyramid – used to visualize food chains
• Pyramid of energy – amount of energy in bodies of
organisms at each trophic level
• Pyramid of numbers – number of organisms feeding at
each trophic level
• Pyramid of biomass – total mass of dry, organic matter at
each trophic level
Matter and Energy Matter
cycles through
the ecosystem
when
one
organismwhen
is passed to another when
and Energy
cycles through
the
ecosystem
eaten
one organism is passed to another when eaten
Pyramid of Energy
Energy decreases up the
pyramid:
• Grass captures sun’s
energy
• Rabbit obtains 10% of
stored energy in grass
• Snake obtains 10% of
stored energy in rabbit
• Eagle receives 10% of
stored energy snake
Pyramid of Energy
1 kcal
10 kcal
100 kcal
1000 kcal
Pyramid of Numbers
Numbers decrease up the
pyramid:
• More individual
organisms at lower
trophic levels
• Fewer individuals at
higher trophic levels
Pyramid of Numbers
Pyramid of Biomass
Biomass decreases up the
pyramid:
• Greatest biomass at
producer level
• Least biomass at tertiary
consumer level
Pyramid of Biomass
Tertiary Consumer
(1.5 grams/square meter)
Secondary Consumer
(11 grams/square meter)
Decomposer
5 grams/square meter
Primary Consumer
(37 grams/square meter)
Producers
807 grams/square meter
Use the 10% rule to see how much energy will get transferred!
Q: If the plants start with 100J of energy how much is in all
the rest of the levels?
Q: If the heron received 3J of energy how much did the plant
start with?
Use the 10% rule to see how much energy will get transferred!
Q: If the primary consumers have 676J of energy how much
is in all the rest of the levels?
Q: If the bass received 1 J of energy how much did the plant
start with?
You will have a quiz in 5 minutes….STUDY!
Trophic Energy Quiz 3 (10pts)
Draw a trophic pyramid to solve each question:
1. If the secondary consumers have 2 J
how much is in all the rest of the levels?
2. If the bass received 100 J of energy
how much did the plant start with?
3. Plants start with 1005 J of energy
how much is in all of the levels?
4. The heron received 3,500 J how
much did the plant start with?
5. Plants started with 500 J
how much did the tertiary consumer get?