Look at page 136, this is your
homework due next class.
Energy Flow and Cycles in Ecosystems
• What’s the matter?
• Where is the energy?
• Will I ever see carbon ?
What is an ecosystem and where does it fit
on the biological scale? Do you remember?
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Sub-Atomic Particles
Atoms
Molecules
Macromolecules
Organelles
Cells
Tissue
Organs
Organ System
Organism
Population
Community
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Biome
Biosphere
Solar System
Universe
• Ecosystem
Atom
Molecule
Macromolecule
Organelle
Cell
Tissue
Organ
System
Organism
Population
Community
Ecosystem
Biome
Biosphere
I. Ecosystems and Energy Flow
A. An ecosystem is a biological community of
interacting organisms and their physical
environment.
B. Ecosystems require a constant input of energy
from either the sun or organic compounds.
What is the ultimate source of energy on plant earth?
II. Energy flows
when organisms
eat
A. Autotroph
= make their
own food from
chemicals or
light
Sun’s energy
photosynthesis
glucose
B. B.
Heterotroph
= must
obtain food
from
environment
How do
organism obtain
energy?
How are organisms arranged in ecosystems?
a. Herbivore
= eat plants
b. Omnivore
= eat flesh
and plants
III. Trophic
Levels
(feeding levels)
A. Producers =
autotrophs that
make their own food
c. Carnivore
= eat flesh
d.
Scavenger
= feed on
organisms that
recently died
B. Consumers =
heterotrophs that eat
other plants and
animals
C. Decomposers
= break down dead
tissue and waste
Which of these are producers?
IV. Types of Producers
A. Photoautotrophs- use light to make food
B. Chemoautotrophs- use chemicals to make food
C. Examples: Plants, algae some bacteria
V. How are consumers classified?
A. First Level Consumer - feed on producers
(Herbivores) The zebra eats the grass.
B. Second Level Consumer - eat first level consumers
(Carnivores) The lion eats the zebra.
C. Tertiary Consumers - eat second level consumers
(Carnivores) The vulture eats the lion.
*Omnivores can be first, second, or third level consumers.
Which of these are first level
consumers?
What is another name for first level
consumers?
Herbivore
Which of these are second level
consumers?
What is another name for a
second level consumer?
Carnivore
VI. Energy Pathways in Ecosystems
A. Food Chain = represents a single pathway
(a specific order) of energy and matter flow through an
ecosystem.
Arrows represent the flow or transfer of energy
b. Not accurate;
eatrepresent?
more than one species
What
do theorganisms
arrows
c. Always begin with a producer
a.
Food Chain
B. Food Web = represent multiple pathways of
energy and matter flow in ecosystems
a. Include many intersecting food chains
b. Most accurate
Aquatic
Food Web
Make a Food Chain Pg 139
Eagle
Daisy
Frog
Coyote
Grasshopper
Answer:
Notice the direction of the arrows.
This shows the flow of energy
FOOD CHAIN page 139
Producers
Grass
Primary
Consumer
Grasshopper
Secondary
Consumer
Snake
Nutrients
Water
Fungi /Bacteria
Decomposers
Draw into Notebook
Tertiary
Consumer
Hawk
Make a food web
Page 138
Fungi
Mountain
Goat
Ladybug
Deer
Bear
Sparrow
Oak Tree
Barn owl
Grass
Spider
Fox
STOP
• Food Web Activity
Where did you get your energy
today?
The ultimate
IN:
source of energy
on planet earth
is the sun!
Energy flows when
organisms eat.
I. Trophic Structure and the Flow of Matter
and Energy
A.Trophic (Feeding )Levels =
organisms that are the same
number of steps from the sun
a. Primary producers (autotrophs)
Incorporate sunlight into
chemical bonds of glucose by
photosynthesis
b. Primary, secondary & tertiary
consumers
Break chemical bonds of
glucose to get energy by cellular
respiration
B. Matter and Energy
a. Flow in and out of ecosystems
b. Are recycled within ecosystems
c. Matter + Energy (IN) = Matter + Energy (OUT)
 Flow
 Cycle
 Conserved
Ecosystems
 Flow
 Cycle
 Conserve
C. Laws of Matter and Energy Apply to Trophic Structure
a. Matter and energy can not be created or
First
Law
destroyed.
b. C, H, O, and N are conserved (combine and recombine) to
make new molecules as they move through ecosystems.
c. There is a gradual loss of energy as it
Second
Law
flows through ecosystems.
d. Organisms use energy for growth, metabolism, and
repair. Or, it is lost as heat to the environment.
II. Ecological Pyramids
= graphical
representations
(pictures) of trophic
structure (feeding
levels)
A. Three Types of Ecological
Pyramids
a. Numbers Pyramid =
represents the total
number of individuals
per unit area
Large numbers of producers form
the base.
b. Biomass Pyramid =
represents the amount of biomass
(dry weight) of living organisms in a
given area at a given time
What are the units used for a
biomass pyramid?
c. Productivity (Energy) Pyramid =
represents the flow of energy
through each trophic level at a
fixed time
What are the units used for an energy pyramid?
What do you notice about the numbers in
each of the pyramids below ?
III. 10 % Rule
a. Only about 10% of the
energy entering a
trophic level is
transferred to the
trophic level above.
b. 90% LOST at each level
c. Energy pyramids have a
step-like pattern
because less energy
enters each trophic
level up the food
chain.
https://www.youtube.com/watch?v=ScizkxMlEOM&list=PL
_4WORZB5ZcqIvhtZefDq7HHVxb1f92l8
DO DEMO
90% LOST
10%
100%
DEMO
Materials:
food coloring, 1000, 100, 10 ml graduated cylinders, one graduated 1ml transfer pipette
• Fill a 1000ml Flask with colored water. (Have student write 1000 ml on board)
• Pour 100 ml into 100 ml graduated cylinder. (Have student write 100 ml on board)
• Ask: What should I do with the rest of the water in the flask if it represents the energy
available in the producers? (throw it away…..lost)
• Repeat for 100 ml and 10 ml cylinders (Have student write 10 ml and write 1 ml on board)
• Show off tiny 1 ml transfer pipette.
• Ask: What does 1ml volume represent? (the only energy left to the 3rd level consumers)
• Ask: Where did all the lost energy go if this is a model of energy flow in a real ecosystem?
( growth, metabolism, repair, lost as heat to the environment)
• Ask: Why do fewer organisms occupy the higher trophic levels?
(Inefficiency in energy transfer between each trophic level)
OUT:
Grass
Mouse
Cat
Coyote
10,000 calories
Suppose 10,000 calories of energy are available at the level of the grasses.
What is the total number of calories LOST by the time energy reaches the coyote?
a. 90 calories
b. 990 calories c. 9900 calories d. 9990 calories
D. 10,000 units in grass
1000 units in mouse
(10,000 X .9 = 9000 lost; 1000 left)
100 units in cat
(1000 X .9 = 900 lost; 100 left)
= 90 lost; 10 left )
Easiest Way 10 units left in coyote (100 X.9
10,000 – 10 = 9990
Knowledge Targets
•Students know atoms of carbon, oxygen, hydrogen, and nitrogen are conserved (i.e., combined and
recombined) to make new molecules as they move through the ecosystem.
•Students know energy flow, mass, and populations in ecology can be represented by pyramids.
•Students know only a fraction of matter consumed at lower trophic levels is transferred to higher
trophic levels to produce growth and release energy through cellular respiration.
•Students know most energy is not transferred to higher trophic levels because it is used for growth,
maintenance, repair, or lost as heat to the environment.
•Students know a small fraction of the energy from one trophic level is transferred to the next higher
trophic level.
•Students know there are fewer organisms at the higher trophic levels of a food web.
Performance Targets
•Students can apply the concept of conservation of matter and energy to food webs and trophic levels.
•Students can identify the relative proportion of organisms at each trophic level (i.e., lowest trophic level
has the greatest biomass and stored energy).
•Students can use mathematical representations to account for the energy transferred through each
trophic level within a food chain.
•Students can explain there are fewer organisms occupying the higher trophic levels due to inefficiency
in energy transfer between each trophic level.