Unit 2: The Biosphere
and Energy Flow
Biosphere & Ecosystem
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Biosphere: Organisms and their environments
(Includes living and dead organic matter)
Ecosystem: A community of organisms (biotic/
living things) and their nonliving (abiotic)
environment (what we learned about in Unit 1)
An ecosystem is a smaller part of the overall
biosphere
I. Energy
A. All organisms need energy to carry out bodily
functions like growing, moving around,
breathing, keeping our blood circulating, etc.
-The ultimate source of energy for life on earth is the
sun.
-Energy is the ability to cause change.
II. How Organisms Obtain Energy
1.
Autotrophs: The producers.
Producers turn light energy from the sun into
food through a process called photosynthesis.
Ex: Trees, plants, algae.
Quick Questions (CFU)
What provides energy for life on earth?
-the sun
What is energy?
-the ability to cause change
Is a producer and an autotroph the same thing?
-yes
What is an example of a producer?
-a plant
III. Heterotrophs
Heterotrophs: The consumers.
A consumer can’t make it’s own food so it has
to eat other organisms.
Ex: Lions, Humans, Rabbits.
IV. Examples of heterotrophs:
1. Herbivore-eats only plants (autotrophs).
Ex: Rabbits
2. Carnivore-eats only animals (heterotrophs).
Ex: Lions
3. Omnivore-eats plants and animals.
Ex: Humans
4. Scavenger-eats dead animals and garbage.
Ex: Vultures
5. Decomposer-breaks down dead or dying material.
Ex: Bacteria, fungi
Questions (CFU)
What is a consumer?
-an organism that cannot make its own food.
What is an example of a consumer?
-humans
Is a consumer the same thing as a heterotroph?
-yes
What kind of heterotroph is this?
-carnivore
What kind of heterotroph is this?
-decomposer
What kind of heterotroph is this?
-herbivore
What kind of heterotroph is this?
-scavenger
Most Humans:
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Omnivores
V. Flow of Matter and Energy
Energy in a Food Chain
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The arrows in a food chain or food web show the
transfer of energy from one organism to another.
B. Food chain - a model that shows
how matter and energy moves through an
ecosystem.
berries → mice → black bear
VI. Flow of Matter and Energy in
Ecosystems
Food Web-a model which shows all possible
feeding relationships at each trophic level in a
community.
***A food web is more realistic than a food
chain because organisms depend on more than
one other species for food.
VII Trophic Levels
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In this class, we will think of these food webs in
_levels_________.
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Level 1: Producers (plants)
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Level 2: Primary Consumers (who eat
producers) Ex: Caterpillar, Giraffe
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Level 3: Secondary Consumers (who eat
Primary Consumers) Ex: Large cats
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Level 4: Tertiary Consumers (who eat
Secondary Consumers) Ex: Hawk
Autotrophs
Third-order
heterotrophs
First-order
heterotrophs
Second-order
heterotrophs
Decomposers
In your notes write examples for the
following:
1. A producer:
A Tree, Algae, Grass, Plants
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2. A primary consumer:
Caterpillar, deer, antelope, cow
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3. A secondary consumer:
Lions (feed on antelope, which feed on plants)
Seeds (producer) → Mice → Snakes
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4. A tertiary consumer:
Seeds (producer) → mice → snakes → Eagles
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II. Flow of Matter and Energy
-Each organism in a food chain is a feeding step,
or trophic level in the movement of matter and
energy.
-Only 10% of energy is passed up each trophic
level!!! (Rule of 10)
-Because so much energy is lost at each trophic
level, there can only be 3-4 steps in a food chain.
You will now practice with these
terms with the worksheet provided
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1. Heterotroph
2. Autotroph
3. Heterotroph
4. Heterotroph
5. Autotroph
6. Heterotroph
7. Heterotroph
8. Autotroph
9. Autotroph
10. Heterotroph
More Answers:
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1. Decomposer
2. Herbivore
3. Omnivore
4. Carnivore
5. Decomposer
6. Scavenger or Omnivore
7. Decomposer
8. Carnivore
9. Herbivore
10. Scavenger
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11 and 12: Producers → Primary Consumer →
secondary consumer → tertiary consumer
4.2.A.a Illustrate and describe the
flow of energy within a food web
Example Food Chain:
Chihuahuan raven
Honey mesquite
(pods eaten by beetles)
Pronghorn
antelope
Example
Gambel
quail
Food Web
Jackrabbit
Long-tail
weasel
Desert
tortoise
Prickly
pear cactus
Coyote
(top carnivore)
Kangaroo rat
(seed eater)Roadrunner
ants Texas horned
lizard
Red spotted
toad
Mexican
whiptail lizard
Mojave
rattlesnake
Questions (fill the answers on WS #2)
What does flow mean?
-to move
Energy flows from _______ to _______ in an ecosystem.
-Energy flows from producer to consumer in an ecosystem.
What is a food chain?
-a model that shows how energy flows in an ecosystem.
What is a food web?
-a model which shows all the feeding relationships in an ecosystem.
Which is more realistic, a food web or a food chain?
-a food web is more realistic than a food chain b/c is shows all
possible feeding relationships.
What is a trophic level? -a feeding step.
How much energy can be passed up each trophic level? -10%
Why can there only be 3-4 trophic levels?
-There can only be 3-4 trophic levels b/c only 10% of the energy is
passed up each level, which means that after 3 or 4 levels, energy
will run out.
Food Web Example #2
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What are the producers?
 Algae and Plants
How can you tell?
 Are at the bottom of food webs; are
green
What three organisms does the fish eat?
 Annelids, Mollusks, and Arthropods
What gives the birds of prey its energy?
 Mammals and Birds
What are Bacteria and fungi known as?
 Decomposers
What do the Bacteria and fungi do?
Breakdown dead organisms
Where are the plants getting inorganic
nutrients from?
 Bacteria and fungi
What are the two top carnivores?
 Birds of prey and Humans
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Answers to WS #3
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1. Produce own food through photosynthesis.
2. Eat other organisms for food.
3. Eat other organisms for food.
4. Break down dead material for energy.
5. 10% is passed up each level.
6. They are using it for life processes such as moving
and breathing and some energy is lost as heat as it is
transferred to different trophic levels.
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Food Webs:
1. Phytoplankton
2. Smaller toothed whales
3. Leopard Seals
4. Krill
5. Phytoplankton and zooplankton
6. other birds, fish, penguins
7. penguins, leopard seals, zooplankton, baleen
whales, elephant seals
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1. Which organisms are the top carnivores? Foxes,
hawks and owls, snakes.
2. snakes
3. rabbits, squirrels, mice, seed-eating birds
4. Plants
5. rabbits, squirrels, mice, seed-eating birds
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WWBAT explain why there are generally more
producers than consumers in an energy pyramid.
WWBAT explain how energy distribution will
change due to changes in the food web.
The last couple of days we have learned about
the terminology of unit 2 and all about food
webs. Today we are learning about energy
pyramids.
A. Types of Food Pyramids:
1. Ecological Pyramids-a model which shows
how energy flows through an ecosystem.
Pyramid of Energy
-Pyramid of Energy-shows
how energy decreases at
each trophic level. Only
10% of the energy is passed
up each level!
Heat
Heat
0.1% Consumers
1% Consumers
10% Consumer
Heat
Heat
100%
Producers
-Pyramid of Biomassshows the weight at each
Biomass
trophic level. (________
means how many living
plants and animals)
Pyramid of Biomass
Pyramid of Numbers
Fox (1)
Birds (25)
Grasshoppers (250)
Grasses (3000)
1 kg of
human tissue
10 kg of beef
100 kg of grain
That means for every 1000 kg of grass
only enough biomass is transferred to
make 1 kg of human tissue.
-Pyramid of Numbers shows the number of
organisms eaten by the
animal above it on the
pyramid.
You will now finish the backs of WS
#3!
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You will work on the worksheet for 20 minutes
and then we will discuss it as a group.
Stay on Task!
Dixie Cup Food Pyramid
(10 cups)
Use the cups provided to build and label your
own food pyramid with the following:
1. Autotroph OR Heterotroph?
2. Producers/Primary/Secondary/Tertiary
Consumers?
3. Carnivore/Herbivore/Omnivore?
4. Percentage of Energy from the Sun?
5. Example Organism? (A picture would be nice)
STOP: You are going for an
interview!
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You are going for an interview and must
become an expert on the following questions in
the next 3 minutes.
Row 1 answer questions 1-5
Row 2 answers questions 6-10
Row 3 answers questions 11-14
We will share out our answers in 3 minutes.
Ready, Set, Go!
Questions: In your notes answer the following questions:
1. What is the Pyramid of Energy?
-shows how much energy is in each trophic level.
2. Does the amount of energy increase or decrease as you go up each trophic level?
-decrease
3. Why does the amount of energy decrease?
-energy is lost to the environment as heat.
4. How much energy is transferred up each level?
10%
5. What is the Pyramid of Numbers?
-shows how many organisms exist at each trophic level.
6. What is the Pyramid of Biomass?
-shows how much weight exists at each trophic level.
7. What is biomass?
-amount of living material
8. Which trophic level has the most biomass?
The producers or the bottom of the pyramid
9. Which trophic level has the least amount of biomass?
The tertiary consumers
10. Give 2 examples for the organisms living at the lowest tropic
level.
Plants, Trees, Algae, Grass
11. Give two examples of organisms at the trophic level that has
the most biomass?
The top, the tertiary consumers
12. If all of the producers were removed from a food
Consumers
web, all the ______________
would eventually
starve to death.
13. If organism A was organism B’s food, and organism
A was removed, the population of organism B
would… Decrease
12. If tarantulas eat crickets and crickets eat plants,
what will happen to the number of plants if all the
tarantulas are removed?
Decrease